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Chris Boar
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Red/Blue shift due to Doppler effect = assumption?
      #5470861 - 10/15/12 12:40 AM

A real basic question on this (my Dad asked me this today actually), just wanted to check on this.

Our estimation on distance to other stars/galaxies based on red shift measurement relies on the premise that red/blue shift is caused by the Doppler effect. But we cannot verify this, we just take it as a given. Is that correct?

If our assumption on the relationship between red shift/doppler effect is wrong then all our distance calculations are incorrect as well. Hubble's law would be wrong, We would in fact have no idea how far away these objects are?

Is my understanding on this correct?


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Chris Boar]
      #5471136 - 10/15/12 09:24 AM

Quote:

A real basic question on this (my Dad asked me this today actually), just wanted to check on this.

Our estimation on distance to other stars/galaxies based on red shift measurement relies on the premise that red/blue shift is caused by the Doppler effect. But we cannot verify this, we just take it as a given. Is that correct?

If our assumption on the relationship between red shift/doppler effect is wrong then all our distance calculations are incorrect as well. Hubble's law would be wrong, We would in fact have no idea how far away these objects are?

Is my understanding on this correct?




Let me help clarify a couple of things here. Almost all galaxies are observed to have redshifted spectral lines. A few nearby galaxies and a few galaxies in the Virgo cluster have blueshifts, but almost all galaxies have redshifts.

For large samples of galaxies with distances estimated from distances indicators such as the Tully-Fisher relation, surface brightness fluctuation method, or Type Ia SN (all of which are calibrated with Cepheid variables), there is a trend of the observed redshift increasing with the distance.

The standard interpretation of this observational result is that the universe is expanding. If this interpretation is incorrect, there is still a trend of redshift increasing with distance, so any alternate theory would need to be able to explain redshift increasing with distance.

There are also doppler shifts interpreted to be superposed upon the expansion redshift. These are due to peculiar motions in large galaxy clusters and amount to no more than ~ 1500 km s-1 at the most for individual galaxies.

Stars within a galaxy are not participating in the expansion of the universe because that affect is small relative to the gravitational forces in a galaxy. So doppler motions are detected for stars in galaxy, but the redshifts and blueshifts are stars within a galaxy are not correlated with distance.

Hope that helps.

Dave


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GlennLeDrew
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5471173 - 10/15/12 09:53 AM

We see Doppler shifting in rotating bodies like the Sun and planets, which are congruent with the rotation rates directly observed. From this we might reasonably conclude that Doppler shifts observed in such phenomena as spectrographic binary stars and stars in clusters (particularly globulars), which seem to accord with dynamical theory and certain other observations, is a real indication of radial velocity. And for the distant galaxies in their turn, Doppler shifts can again, by extrapolation, be reasonably assumed to indicate motion along the line of sight.

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Chris Boar
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5471997 - 10/15/12 06:01 PM

Thanks guy's, that makes sense.

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deSitter
Still in Old School


Reged: 12/09/04

Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5472267 - 10/15/12 08:48 PM

Quote:

We see Doppler shifting in rotating bodies like the Sun and planets, which are congruent with the rotation rates directly observed. From this we might reasonably conclude that Doppler shifts observed in such phenomena as spectrographic binary stars and stars in clusters (particularly globulars), which seem to accord with dynamical theory and certain other observations, is a real indication of radial velocity. And for the distant galaxies in their turn, Doppler shifts can again, by extrapolation, be reasonably assumed to indicate motion along the line if sight.




Neverthess, it *is* possible to provide a purely kinematic explanation of cosmic redshifts. Whether or not it's the right one, it still is extremely interesting that this is even possible.

-drl


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GlennLeDrew
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5476492 - 10/18/12 07:56 AM

And is it not a *kinematic* relationship which I'm supporting, as opposed to some 'tired light' theory or some such?

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Jarad
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5476517 - 10/18/12 08:20 AM

I think he means purely kinematic in the sense that the various galaxies just happen to moving at those speeds, as opposed to due to the expansion of the universe.

Is that correct, Danny?

Jarad


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GlennLeDrew
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Jarad]
      #5476528 - 10/18/12 08:38 AM

Color me naive, for I see 'kinematic' velocity and expansion of the universe as the same thing. In both cases the object is moving, as revealed by Doppler shifts. The ultimate extension of this is the redward shift into the microwave regime the echo of the big bang (again, paint me gullible.)

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Neutrino?
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Reged: 12/14/09

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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5476945 - 10/18/12 01:16 PM

Quote:

Color me naive, for I see 'kinematic' velocity and expansion of the universe as the same thing. In both cases the object is moving, as revealed by Doppler shifts. The ultimate extension of this is the redward shift into the microwave regime the echo of the big bang (again, paint me gullible.)




No. (Currently, it is accepted that) Cosmological redshift is not due to kinematics. There is no conservation law for energy along geodesics in the FRW metric as it is not symmetric in time. This metric is used to describe the metric expansion of space in GR.

Edited by Neutrino? (10/18/12 01:18 PM)


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deSitter
Still in Old School


Reged: 12/09/04

Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Jarad]
      #5477200 - 10/18/12 03:14 PM

Quote:

I think he means purely kinematic in the sense that the various galaxies just happen to moving at those speeds, as opposed to due to the expansion of the universe.

Is that correct, Danny?

Jarad




Actually I mean by dint of geometry itself. The trees in China are upside down relative to ours. That does not mean they are being pushed over by a mysterious dynamical tree pushing force. They grow on a sphere, not a plane. The BB adopts a dynamical explanation by assuming the trees are carried along with space that expands from nothing.

-drl


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Pess
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5494771 - 10/29/12 02:46 PM

Quote:

Quote:

We see Doppler shifting in rotating bodies like the Sun and planets, which are congruent with the rotation rates directly observed. From this we might reasonably conclude that Doppler shifts observed in such phenomena as spectrographic binary stars and stars in clusters (particularly globulars), which seem to accord with dynamical theory and certain other observations, is a real indication of radial velocity. And for the distant galaxies in their turn, Doppler shifts can again, by extrapolation, be reasonably assumed to indicate motion along the line if sight.




Neverthess, it *is* possible to provide a purely kinematic explanation of cosmic redshifts. Whether or not it's the right one, it still is extremely interesting that this is even possible.

-drl




I wonder. Since redshifts are a function (supposedly) of distance. Would it be possible to observe say, several distant objects over the course of years and graph a subtle change (increase) in redshift of these observed objects as they recede from us?

I just did some back of envelope calculations and it appears we need more sensitive instruments by a factor of two and/or perhaps at least 50 to a 100 years of observing time?

I think that might settle the redshift question once and for-all.

Pesse (Just thinking out loud) Mist


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Kobayashi
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Pess]
      #5495065 - 10/29/12 05:47 PM

Quote:

Since redshifts are a function (supposedly) of distance. Would it be possible to observe say, several distant objects over the course of years and graph a subtle change (increase) in redshift of these observed objects as they recede from us?




If you're talking about redshift of galaxies, the redshift is smeared by all the internal motion within the galaxy (i.e. movement of individual stars within the galaxy), so I don't think you'll get a very good precision. Also, since galaxies are tens or thousands of light-years across, you won't see any fluctuation at a timescale shorter than tens of thousands of years.


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Jarad
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Kobayashi]
      #5495219 - 10/29/12 07:54 PM

You would have to use something like a quasar. Those are presumed to be physically small, and giving off large amounts of light.

Still not trivial, but if it can be measured with sufficient precision, we could potentially measure a shift in a high-Z quasar over a few hundred years or so.

Sounds perfect for a new grad student to take on...

Jarad


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Rick Woods
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Kobayashi]
      #5495421 - 10/29/12 10:15 PM

Quote:

[If you're talking about redshift of galaxies, the redshift is smeared by all the internal motion within the galaxy (i.e. movement of individual stars within the galaxy), so I don't think you'll get a very good precision.




Is that true? I would think the redshift of a distant galaxy indicative of relativistic speeds, while any local motion within the galaxy itself should be almost indetectable.


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deSitter
Still in Old School


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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Jarad]
      #5495729 - 10/30/12 03:28 AM

Quote:

You would have to use something like a quasar. Those are presumed to be physically small, and giving off large amounts of light.

Still not trivial, but if it can be measured with sufficient precision, we could potentially measure a shift in a high-Z quasar over a few hundred years or so.

Sounds perfect for a new grad student to take on...

Jarad




Yes or an AGN presumably embedded in thick material. The first step is to start looking.

-drl


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Rick Woods]
      #5495900 - 10/30/12 09:08 AM

Quote:

Quote:

[If you're talking about redshift of galaxies, the redshift is smeared by all the internal motion within the galaxy (i.e. movement of individual stars within the galaxy), so I don't think you'll get a very good precision.




Is that true? I would think the redshift of a distant galaxy indicative of relativistic speeds, while any local motion within the galaxy itself should be almost indetectable.




Rotation curves are measured by measuring the redshift of a galaxy across its disk. See for example figure 5-8 of this paper:

http://adsabs.harvard.edu/abs/1997AJ....114.2402C

(click on "Full refereed article (pdf/postscript)

So redshift varies across the disk in a systematic way that is consistent with rotation. The figures put the redshift of the nucleus at zero. The redshift relative to that value is mapped across the disk and results from doppler effects due to one side of the galaxy rotating toward us in the line of sight and the other side of the galaxy rotating away from us in the line of sight.

The problem is really the timescales involved in detecting a change in redshift. As part of a paper I just submitted I listed the observed redshift values of the galaxy being discussed and the measured redshift values had a range of 110 km s-1. With a Hubble constant of 70 km s-1 Mpc-1 that is equivalent to a distance of ~1.5 Megaparsecs. Note the galaxy has not actually moved 1.5 Mpc in the 20 years of measurements the data covers. That is just the range of redshift values provided by different instruments. So the uncertainty in our redshift measurements will swamp out any changes in expansion redshifts over any timescales realistic for us to conduct measurements.

Dave


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Chris Boar]
      #5495961 - 10/30/12 10:09 AM

Quote:

A real basic question on this (my Dad asked me this today actually), just wanted to check on this.

Our estimation on distance to other stars/galaxies based on red shift measurement relies on the premise that red/blue shift is caused by the Doppler effect. But we cannot verify this, we just take it as a given. Is that correct?

If our assumption on the relationship between red shift/doppler effect is wrong then all our distance calculations are incorrect as well. Hubble's law would be wrong, We would in fact have no idea how far away these objects are?

Is my understanding on this correct?




Maybe it is worth coming back to the original questions. When Hubble published the first velocity-distance result in 1929 he did not assume that there was a law in which redshift increases with distance. What he noticed is that there is a correlation between the observed redshifts of the galaxies in his sample and the distances to those derived from the magnitudes of stars within the individual galaxies. So as the distance to the galaxy increases, the observed redshift velocity increases.

Hubble did interpret scatter in the velocity-distance relationship as coming from two primary sources:

1. Errors in his distances derived from magnitude data
2. Doppler motions of individual galaxies (peculiar motions)

With Hubble's original data he inferred peculiar motions should be small - typically less than about 200 km s-1. Hubble's original distances were severely in error due to less precision of magnitude measures and an incorrect calibration of the Cepheid distance scale. So his original value of what has become known as the "Hubble Constant" was over 500 km s-1 Mpc-1.

Hubble himself was very cautious about interpreting the velocity-distance relationship. While the research community preferred an expanding universe interpretation Hubble was not really committed to that or any other interpretation.

Jump ahead to modern data. Modern calibrations of the Cepheid distance scale applied to secondary distance indicators methods such as the Surface Brightness fluctuation method, Tully-Fisher Relation, Type Ia SN, Type II SN, Tip of the red Giant branch ... and a few other methods have led to a very clear picture that redshift increases with distance ... for the normal galaxies to which these methods can be applied.

This is a very important realty that people need to understand. Even in Halton Arp's "intrinsic redshift" models there is an underlying redshift-distance relationship upon which his "intrinsic" redshifts would be superposed.

What mainstream astrophysical research community sees in all their data is that there are no significant deviations from the Hubble law. When evidence appears that suggests the possibility that some very high redshift objects could actually be much closer than their redshifts imply the mainstream response is that the evidence results from purely chance alignments of lower redshift foreground objects with higher redshift background objects.

For example one of the most famous cases is NGC 7603:

http://adsabs.harvard.edu/abs/2002A%26A...390L..15L

The spiral galaxy NGC 7603 is apparently connected to the companion NGC 7603B by a bridge of material. These sorts of bridges are always interpreted as evidence for interaction between two objects. But in this case NGC 7603 has a redshift of ~8700 km s-1 wherease the companion NGC 7603b has a redshift of 16700 km s-1. Since interaction models cannot generate a redshift difference this large the mainstream concludes that NGC 7603b is a background object. However, Arp and supporters point out correctly that NGC 7603B is the most obvious candidate to explain the existence of the luminous filament that appears to connect the two objects.

Another example that has gotten no attention is the radio galaxy B21637+29. In 1988 de Ruiter et al observed this galaxy and found that the interacting companion had a redshift ~4300 km s-1 greater than the main galaxy. They went on to develop an interaction scenario that was capable of explaining the redshift differential as resulting from a strong interaction. Then in 1998 they measured additional redshifts in the cluster and found out that additional galaxies in the cluster also had the 4000 km s-1 greater redshift even though they were not involved in interactions. This created a dilema for mainstream views that de Ruiter et al correctly characterized. Either the 4000 km s-1 higher redshift group is a background group which means there is no explanation for the strong interaction evidence for B2 1637+29 or... the higher redshift group is at the same distance as B2 1637+29 in which case we would have to accept entire groups of galaxies moving at 4000 km s-1 relative to the Hubble flow. Here is the 1998 paper:

http://adsabs.harvard.edu/abs/1998A%26A...337..711D

Note that this important paper has been cited exactly twice in 14 years - both times by Lopez-Corredoira whom published the NGC 7603 paper. How can this be? Nobody in the astrophysics research community wants to explore the implications of this? Only one researcher in 14 years has cited this important paper that identifies a 4000 km s-1 deviation from Hubble's law! And 4000 km s-1 is halfway to the difference between NGC 7603 and NGC 7603B. If a 4000 km s-1 diffeence is possible, then why not an 8000 km s-1 difference?

As a final example there is NGC 1275 - an active galaxy with a 3000 km s-1 higher redshift galaxy superposed in front of it on our line of sight:

http://adsabs.harvard.edu/abs/1996Ap.....39..334M

http://adsabs.harvard.edu/abs/1992ApJ...388..301C

There is a universe of possibilities out there involving devations from Hubble's law that the astrophysics research community avoids investigating. I don't understand why there is such resistance. It is well established that a Hubble relationship exists for most normal galaxies. It would not require abandoning the current cosmological model to acknowledge that our universe contains anomalous redshift objects.

Dave


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GlennLeDrew
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5496172 - 10/30/12 01:17 PM

I would be most cautious of interpreting 'connecting bridges' based on appearance alone. There must be more robust evidence to confirm that they result from more than chance superposition. One effect to be aware of is that subtle features can be made more apparent when seen against another smooth source. An example is the M110's tidal tail, being more apparent where seen against the faint, smooth glow in the outer parts of M31. Someone not acquainted with tidal effects might interpret this as a connecting bridge. Of course, we know with some confidence that M31 and M110 are effectively interacting. But suppose M110 was a very much more distant object having the same tidal tail-like extension; it might initially give the impression of a 'connection' to the foreground M31.

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deSitter
Still in Old School


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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5496322 - 10/30/12 02:53 PM

Quote:

Quote:

A real basic question on this (my Dad asked me this today actually), just wanted to check on this.

Our estimation on distance to other stars/galaxies based on red shift measurement relies on the premise that red/blue shift is caused by the Doppler effect. But we cannot verify this, we just take it as a given. Is that correct?

If our assumption on the relationship between red shift/doppler effect is wrong then all our distance calculations are incorrect as well. Hubble's law would be wrong, We would in fact have no idea how far away these objects are?

Is my understanding on this correct?




Maybe it is worth coming back to the original questions. When Hubble published the first velocity-distance result in 1929 he did not assume that there was a law in which redshift increases with distance. What he noticed is that there is a correlation between the observed redshifts of the galaxies in his sample and the distances to those derived from the magnitudes of stars within the individual galaxies. So as the distance to the galaxy increases, the observed redshift velocity increases.

Hubble did interpret scatter in the velocity-distance relationship as coming from two primary sources:

1. Errors in his distances derived from magnitude data
2. Doppler motions of individual galaxies (peculiar motions)

With Hubble's original data he inferred peculiar motions should be small - typically less than about 200 km s-1. Hubble's original distances were severely in error due to less precision of magnitude measures and an incorrect calibration of the Cepheid distance scale. So his original value of what has become known as the "Hubble Constant" was over 500 km s-1 Mpc-1.

Hubble himself was very cautious about interpreting the velocity-distance relationship. While the research community preferred an expanding universe interpretation Hubble was not really committed to that or any other interpretation.

Jump ahead to modern data. Modern calibrations of the Cepheid distance scale applied to secondary distance indicators methods such as the Surface Brightness fluctuation method, Tully-Fisher Relation, Type Ia SN, Type II SN, Tip of the red Giant branch ... and a few other methods have led to a very clear picture that redshift increases with distance ... for the normal galaxies to which these methods can be applied.

This is a very important realty that people need to understand. Even in Halton Arp's "intrinsic redshift" models there is an underlying redshift-distance relationship upon which his "intrinsic" redshifts would be superposed.

What mainstream astrophysical research community sees in all their data is that there are no significant deviations from the Hubble law. When evidence appears that suggests the possibility that some very high redshift objects could actually be much closer than their redshifts imply the mainstream response is that the evidence results from purely chance alignments of lower redshift foreground objects with higher redshift background objects.

For example one of the most famous cases is NGC 7603:

http://adsabs.harvard.edu/abs/2002A%26A...390L..15L

The spiral galaxy NGC 7603 is apparently connected to the companion NGC 7603B by a bridge of material. These sorts of bridges are always interpreted as evidence for interaction between two objects. But in this case NGC 7603 has a redshift of ~8700 km s-1 wherease the companion NGC 7603b has a redshift of 16700 km s-1. Since interaction models cannot generate a redshift difference this large the mainstream concludes that NGC 7603b is a background object. However, Arp and supporters point out correctly that NGC 7603B is the most obvious candidate to explain the existence of the luminous filament that appears to connect the two objects.

Another example that has gotten no attention is the radio galaxy B21637+29. In 1988 de Ruiter et al observed this galaxy and found that the interacting companion had a redshift ~4300 km s-1 greater than the main galaxy. They went on to develop an interaction scenario that was capable of explaining the redshift differential as resulting from a strong interaction. Then in 1998 they measured additional redshifts in the cluster and found out that additional galaxies in the cluster also had the 4000 km s-1 greater redshift even though they were not involved in interactions. This created a dilema for mainstream views that de Ruiter et al correctly characterized. Either the 4000 km s-1 higher redshift group is a background group which means there is no explanation for the strong interaction evidence for B2 1637+29 or... the higher redshift group is at the same distance as B2 1637+29 in which case we would have to accept entire groups of galaxies moving at 4000 km s-1 relative to the Hubble flow. Here is the 1998 paper:

http://adsabs.harvard.edu/abs/1998A%26A...337..711D

Note that this important paper has been cited exactly twice in 14 years - both times by Lopez-Corredoira whom published the NGC 7603 paper. How can this be? Nobody in the astrophysics research community wants to explore the implications of this? Only one researcher in 14 years has cited this important paper that identifies a 4000 km s-1 deviation from Hubble's law! And 4000 km s-1 is halfway to the difference between NGC 7603 and NGC 7603B. If a 4000 km s-1 diffeence is possible, then why not an 8000 km s-1 difference?

As a final example there is NGC 1275 - an active galaxy with a 3000 km s-1 higher redshift galaxy superposed in front of it on our line of sight:

http://adsabs.harvard.edu/abs/1996Ap.....39..334M

http://adsabs.harvard.edu/abs/1992ApJ...388..301C

There is a universe of possibilities out there involving devations from Hubble's law that the astrophysics research community avoids investigating. I don't understand why there is such resistance. It is well established that a Hubble relationship exists for most normal galaxies. It would not require abandoning the current cosmological model to acknowledge that our universe contains anomalous redshift objects.

Dave




Great post. It's very important to understand that the Hubble relation is real. I am convinced that some redshifts are intrinsic, but they appear, as you say, superposed on the Hubble effect. Too often "Arpists" are stridently against any redshift that has cosmic interpretations, while those who denigrate them often appear to be unwilling to even look with an open mind. Sounds like politics no?

-drl


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5496327 - 10/30/12 02:55 PM

Quote:

I would be most cautious of interpreting 'connecting bridges' based on appearance alone. There must be more robust evidence to confirm that they result from more than chance superposition. One effect to be aware of is that subtle features can be made more apparent when seen against another smooth source. An example is the M110's tidal tail, being more apparent where seen against the faint, smooth glow in the outer parts of M31. Someone not acquainted with tidal effects might interpret this as a connecting bridge. Of course, we know with some confidence that M31 and M110 are effectively interacting. But suppose M110 was a very much more distant object having the same tidal tail-like extension; it might initially give the impression of a 'connection' to the foreground M31.




There is a large class of galaxies that are morphologically similar - grand spiral with irregular companion connected by a material bridge. Why should these be any different? In fact the onus would be on the person proposing chance alignment, not the one assuming the simplest possibility.

-drl


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llanitedave
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5497030 - 10/30/12 10:44 PM

I would think the simplest possibility is the one that doesn't require a whole new physics to explain.

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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5497044 - 10/30/12 10:55 PM

Quote:

I would be most cautious of interpreting 'connecting bridges' based on appearance alone. There must be more robust evidence to confirm that they result from more than chance superposition. One effect to be aware of is that subtle features can be made more apparent when seen against another smooth source. An example is the M110's tidal tail, being more apparent where seen against the faint, smooth glow in the outer parts of M31. Someone not acquainted with tidal effects might interpret this as a connecting bridge. Of course, we know with some confidence that M31 and M110 are effectively interacting. But suppose M110 was a very much more distant object having the same tidal tail-like extension; it might initially give the impression of a 'connection' to the foreground M31.




Glenn,

The research literature is littered with discussion of luminous bridges and filaments indicating interaction between two galaxies. A bridge is a standard form of evidence for interaction. The only distinction between NGC 7603/NGC 7603B and the numerous accepted bridged interactions is the redshift differential.

Even on the SDSS SkyServer NGC 7603/NGC 7603B is listed as an interacting pair:

http://skyserver.sdss.org/edr/en/tools/places/page5.asp

This is a classic case where a definitive test could be made if researchers would get the required data. As an early type galaxy NGC 7603B could have its distance determined via the Surface Brightness Fluctuation Method. But that would require somebody choose to take the risk of ridicule that might come their way if the SBF distance of NGC 7603B turned out to be the same as NGC 7603. It's safer just to avoid that possibility altogether.

But the reality is that the bridge itself is evidence for interaction. Any image of this system I've ever seen shows the bridge terminating precisely at NGC 7603B. A bridge of this type is generated by interaction. If the interacting companion is not NGC 7603B, then what object is responsible for the bridge?

Note that I am not saying the bridge is proof of interaction. I'm saying it is evidence for interaction. The only tests that would prove interaction would be reliable redshift independent distance estimates for both NGC 7603 and NGC 7603B. The existence of the bridge is enough evidence to justify further investigation of the redshift anomoly of this system.


Dave


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5497058 - 10/30/12 11:08 PM

Quote:

Great post. It's very important to understand that the Hubble relation is real. I am convinced that some redshifts are intrinsic, but they appear, as you say, superposed on the Hubble effect.




Right, In an intrinsic redshift model there is an underlying redshift-distance relation defined by some value of the Hubble constant upon which intrinsic redshifts would be superposed. For normal galaxies the intrinsic redshifts would be small. For quasars the intrinsic redshifts would be very large.

Quote:

Too often "Arpists" are stridently against any redshift that has cosmic interpretations,




It is often the case that those who read and become enamored by Arp's work fail to recognize that Arp himself thinks there is an underlying redshift-distance relation defined by a Hubble Constant of 55 km s-1 Mpc-1. For normal galaxies the observed redshift velocity would be comprised of 3 components:

Vobs = H0r + Vpec + Vint

Where Vobs is the observed redshift velocity; H0r is the Hubble constant x the distance (r); Vpec is a peculiar velocity component; and Vint is the intrinsic redshift component.

The problem is you can't really identify intrinsic redshifts that are small as intrinsic redshifts because they are too easily interpreted as peculiar motions. You need to identify instances where the observations indicate the galaxy would have a redshift deviation too large to be a peculiar motion - such as in NGC 7603B.


Quote:

while those who denigrate them often appear to be unwilling to even look with an open mind. Sounds like politics no?




Well, the problem is with the wealth of different things that could be studied almost nobody is interested in looking into the redshift anomalies for fear of being labeled a quack. That doesn't exactly sound like a promising direction for a young researcher looking to establish their reputation. Unfortunately, a system that declares viable scientific possibilities as off-limits for study actually slows the progress of science.

Dave

-drl




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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: llanitedave]
      #5497070 - 10/30/12 11:23 PM

Quote:

I would think the simplest possibility is the one that doesn't require a whole new physics to explain.




Simplicity is a terrible criteria for judging the fitness of a hypothesis, theory, or interpretation of the data. Observational evidence is how scientific ideas are tested.

Simplicity is no longer relevant when you get to the point of distinguishing published ideas. Simplicity is utilized in developing an idea in the first place. Once developed and put forward to challenge a different theory the evidence is the deciding factor.

If we take NGC 7603/NGC 7603B as an example ... all that is needed is someone to get a SBF distance to NGC 7603B and perhaps the same method could be used on NGC 7603 if the nuclear/bulge region was studied since the SBF method is better applied to early type galaxies. If the two galaxies have the same SBF distance within the uncertainty of the measurements and calibration then you've established that large redshift anomalies are real in some objects. If the SBF distances do not agree, then you've dealt a significant blow to the Arp model. That is how science is supposed to work. Simplicity has nothing to do with it. If the SBF distances of NGC 7603 and NGC 7603B are the same you're going to need new physics whether that makes things less simple or not.

The "new physics" with regards to Arp is just much about nothing. Dark energy is new physics. I don't here anyone in the mainstream astrophysics research community objecting to dark energy on the grounds that it requires new physics.

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances? Does anybody actual think after looking at the scientific advances of the last 100 years that it is preposterous that the future will not bring about new physics?

Dave


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Kobayashi
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5497094 - 10/30/12 11:52 PM

Quote:

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances?




Science advances when we find observations and data that cannot be explained by our existing, established theories. Looking for alternate explanations for observations that we can already explain is not science, it's fantasy or fiction.


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Rick Woods
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Kobayashi]
      #5497157 - 10/31/12 12:36 AM

Quote:

Quote:

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances?




Science advances when we find observations and data that cannot be explained by our existing, established theories. Looking for alternate explanations for observations that we can already explain is not science, it's fantasy or fiction.




Not necessarily. Epicycles explained planetary motions to the satisfaction of the scientific community of the day. Aristotle was the last word in science for centuries, until people began thinking for themselves and looking at things in different ways.

There's nothing sacred about existing, established theories. They're still just theories. If someone doesn't like them, that's when a better one gets developed. (Or a worse one, which then gets shot full of holes and discarded. That's how science advances.)


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Kobayashi
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Rick Woods]
      #5497198 - 10/31/12 01:23 AM

Quote:

Epicycles explained planetary motions to the satisfaction of the scientific community of the day.




And it wasn't rejected until higher accuracy observations were made, and the discrepancy between prediction and observation became clear.

Quote:

There's nothing sacred about existing, established theories. They're still just theories. If someone doesn't like them, that's when a better one gets developed.




"Just a theory" is a phrase that demonstrates profound misunderstanding of what a scientific theory is. A scientific theory is not a mere hypothesis; it's an explanation of the world that has been thoroughly confirmed by observations and experimentation (cite). You don't throw it away without very good reason.


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5497289 - 10/31/12 04:51 AM

Quote:

Quote:

I would think the simplest possibility is the one that doesn't require a whole new physics to explain.




Simplicity is a terrible criteria for judging the fitness of a hypothesis, theory, or interpretation of the data. Observational evidence is how scientific ideas are tested.

Simplicity is no longer relevant when you get to the point of distinguishing published ideas. Simplicity is utilized in developing an idea in the first place. Once developed and put forward to challenge a different theory the evidence is the deciding factor.

If we take NGC 7603/NGC 7603B as an example ... all that is needed is someone to get a SBF distance to NGC 7603B and perhaps the same method could be used on NGC 7603 if the nuclear/bulge region was studied since the SBF method is better applied to early type galaxies. If the two galaxies have the same SBF distance within the uncertainty of the measurements and calibration then you've established that large redshift anomalies are real in some objects. If the SBF distances do not agree, then you've dealt a significant blow to the Arp model. That is how science is supposed to work. Simplicity has nothing to do with it. If the SBF distances of NGC 7603 and NGC 7603B are the same you're going to need new physics whether that makes things less simple or not.

The "new physics" with regards to Arp is just much about nothing. Dark energy is new physics. I don't here anyone in the mainstream astrophysics research community objecting to dark energy on the grounds that it requires new physics.

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances? Does anybody actual think after looking at the scientific advances of the last 100 years that it is preposterous that the future will not bring about new physics?

Dave




While it is stated in the papers of Lopez-C, we should for thread purposes mention that the bridge between 7603/B also contains two small knots which themselves have extremely anomalous redshifts, see here:

http://quasars.org/ngc7603.htm

-drl


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Kobayashi]
      #5497431 - 10/31/12 08:48 AM

Quote:

Quote:

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances?




Science advances when we find observations and data that cannot be explained by our existing, established theories.




Yes - like two objects apparently connected by a bridge of luminous material that have an 8000 km s-1 difference in redshift.

Quote:

Looking for alternate explanations for observations that we can already explain is not science, it's fantasy or fiction.




Two things - First, that is not the situation we are discussing. NGC 7603/NGC 7603B is an anomalous redshift pairing that is not explained by standard theories if the two objects are in fact interacting as the luminous bridge would indicate.

Second, There is no rule in science that an alternate theory cannot be brought forward to explain observations that are already explained. The key component of an alternate theory would be that it would need to explain things that the standard theory is incapable of explaining or make predictions different in some aspects from the standard theory.

Dave


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5497438 - 10/31/12 08:54 AM

Quote:


Second, There is no rule in science that an alternate theory cannot be brought forward to explain observations that are already explained. The key component of an alternate theory would be that it would need to explain things that the standard theory is incapable of explaining or make predictions different in some aspects from the standard theory.

Dave




Exactly, this is how things always move forward, without exception. In the case of GR, a residual error of 0.012 degree per century in the orbit of Mercury was sufficient cause to re-explain the already explained, the idea of Newton's central force and action at a distance.

-drl


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5497439 - 10/31/12 08:54 AM

Quote:

Quote:

Quote:

I would think the simplest possibility is the one that doesn't require a whole new physics to explain.




Simplicity is a terrible criteria for judging the fitness of a hypothesis, theory, or interpretation of the data. Observational evidence is how scientific ideas are tested.

Simplicity is no longer relevant when you get to the point of distinguishing published ideas. Simplicity is utilized in developing an idea in the first place. Once developed and put forward to challenge a different theory the evidence is the deciding factor.

If we take NGC 7603/NGC 7603B as an example ... all that is needed is someone to get a SBF distance to NGC 7603B and perhaps the same method could be used on NGC 7603 if the nuclear/bulge region was studied since the SBF method is better applied to early type galaxies. If the two galaxies have the same SBF distance within the uncertainty of the measurements and calibration then you've established that large redshift anomalies are real in some objects. If the SBF distances do not agree, then you've dealt a significant blow to the Arp model. That is how science is supposed to work. Simplicity has nothing to do with it. If the SBF distances of NGC 7603 and NGC 7603B are the same you're going to need new physics whether that makes things less simple or not.

The "new physics" with regards to Arp is just much about nothing. Dark energy is new physics. I don't here anyone in the mainstream astrophysics research community objecting to dark energy on the grounds that it requires new physics.

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances? Does anybody actual think after looking at the scientific advances of the last 100 years that it is preposterous that the future will not bring about new physics?

Dave




While it is stated in the papers of Lopez-C, we should for thread purposes mention that the bridge between 7603/B also contains two small knots which themselves have extremely anomalous redshifts, see here:

http://quasars.org/ngc7603.htm

-drl




Yes - the HII galaxies in the filament are another aspect of this system. To me the big problem with them is that there is no obvious means to establish that they are in fact interacting with the filament.

This has always been the problem with Arp's local quasars model. The whole thing gets bogged down in statistics because there are no redshift independent distance estimates for quasars. While Arp's first anomalous redshift evidence involved quasars, I think ultimately the way to get there is a more bottom up approach. Convincing evidence needs to be brought forward establishing that normal galaxies have anomalous redshift deviations too large to be accounted for by peculiar motions - something Arp has also argued. Statistical arguments just don't resolve the issue because no matter how low the probability of a chance alignment it can always be argued that it is still an accidental alignment ... or even the statistical analysis can be endlessly debated. This is in fact what has gone on with Arp's ideas for decades.

Dave


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Pess
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5497531 - 10/31/12 10:15 AM

Quote:


The problem is really the timescales involved in detecting a change in redshift. As part of a paper I just submitted I listed the observed redshift values of the galaxy being discussed and the measured redshift values had a range of 110 km s-1. With a Hubble constant of 70 km s-1 Mpc-1 that is equivalent to a distance of ~1.5 Megaparsecs. Note the galaxy has not actually moved 1.5 Mpc in the 20 years of measurements the data covers. That is just the range of redshift values provided by different instruments. So the uncertainty in our redshift measurements will swamp out any changes in expansion redshifts over any timescales realistic for us to conduct measurements.

Dave




That's pretty much my thought on just figuring it out on scratch paper.

The further an object is away from us the faster it is receding and so the less time needed to detect it.

I think the problem is two-fold. Timescale for detection & sensitivity of detecting instruments.

Obviously a large number of distant (extragalactic) objects would be observed over a long period of time to provide a definite answer.

Quasars, AGN's and anything else we can viably measure so the results are not object-target specific.

Obviously this experiment would depend on the sensitivity of the measurements. I suspect if we could double our present instrument sensitivity we could find an answer in a minimum of about 50 years of observation.

Pesse (I'll haul my Meade 2.0" Refractor out tonight and start measuring!) Mist


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Pess
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Pess]
      #5497588 - 10/31/12 11:04 AM

Quote:

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances? Does anybody actual think after looking at the scientific advances of the last 100 years that it is preposterous that the future will not bring about new physics?

Dave




I have felt for a long time that we are just on the verge of something new. Like Einstein flipped the world with his realization about the nature of light.

The Standard Model is a complex particle zoo that begs for a simpler underpinning.

We can describe gravity but can't really explain it.

Einstein came up with some new ideas that greatly simplified things compared to previous models..just as Copernicanism simplified astronomy even though Ptolemy epicycles already explained things (albeit in a very complicated and not particularly satisfying way).

In short, we got a long way to go before we understand physics completely.

Pesse (Heck, we can't even figure out what's going on in a bottle of powdered Palladium & water when a current is run through it!) Mist


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GlennLeDrew
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Pess]
      #5498271 - 10/31/12 06:59 PM

In looking over a variety of images of the NGC7603 pair, I see no compelling reason to think the 'bridge' is nothing more than one of the larger object's spiral arms, which by chance happens to terminate at the smaller object. If such a bridge is the result of tidal stripping of stars from the interloper, there should be an 'anti-tail' of length at least some small fraction of that of the tail apparent here. If the 'bridge' is a spiral arm of the larger galaxy, it does not seem to be warped or distorted to any notable degree.

The high redshift 'knots' could well be background objects, too.


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5498572 - 10/31/12 10:15 PM

Quote:

In looking over a variety of images of the NGC7603 pair, I see no compelling reason to think the 'bridge' is nothing more than one of the larger object's spiral arms, which by chance happens to terminate at the smaller object. If such a bridge is the result of tidal stripping of stars from the interloper, there should be an 'anti-tail' of length at least some small fraction of that of the tail apparent here. If the 'bridge' is a spiral arm of the larger galaxy, it does not seem to be warped or distorted to any notable degree.




If the two objects are interacting and at the same distance then the problem is a gravitational interaction scenario is simply not going to be able to explain an 8000 km s-1 redshift difference. Instead what is proposed for systems like this is that the lower redshift object - which in this case is an active Seyfert galaxy - has ejected the higher redshift object from its core. In an ejection scenario there is no counter tail to the ejection. The filament we see between NGC 7603 and NGC 7603B is matter entrained in the outward movement of the ejected object.

Here is what the SDSS SkyServer has to say about this pair:

Quote:

NGC 7603/ PGC 07041, an interacting pair. Notice the bridge between the two galaxies. The bigger object, NGC 7603, is a well-known Seyfert galaxy. These are known for their very small and bright core.




http://skyserver.sdss.org/edr/en/tools/places/page5.asp

Quote:

The high redshift 'knots' could well be background objects, too.




Yes they could be. As could NGC 7603B. The difference is that NGC 7603B provides the possibility of a redshift independent distance estimate since it is a normal looking early type galaxy.

Dave


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llanitedave
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5498652 - 10/31/12 11:02 PM

Quote:

Quote:

Quote:

On a more philosophical note I have to wonder why anyone would object to observations/interpretations that imply we might need some new physics. Isn't that how science advances?




Science advances when we find observations and data that cannot be explained by our existing, established theories.




Yes - like two objects apparently connected by a bridge of luminous material that have an 8000 km s-1 difference in redshift.

Quote:

Looking for alternate explanations for observations that we can already explain is not science, it's fantasy or fiction.




Two things - First, that is not the situation we are discussing. NGC 7603/NGC 7603B is an anomalous redshift pairing that is not explained by standard theories if the two objects are in fact interacting as the luminous bridge would indicate.

Second, There is no rule in science that an alternate theory cannot be brought forward to explain observations that are already explained. The key component of an alternate theory would be that it would need to explain things that the standard theory is incapable of explaining or make predictions different in some aspects from the standard theory.

Dave




The problem for me is that those who are insisting that a new physics of red shift is necessary to explain these anomalies have had some 30-odd years to propose some sort of physical mechanism for it. I've yet to see one that's even serious. Surely all the creative mathematical and physics-minded folks out there haven't been idle?


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Ira
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: llanitedave]
      #5498676 - 10/31/12 11:19 PM

We can PROVE that objects in motion undergo a doppler shift. It's easy for sound. I assume it is also demonstrable for light. (I say "assume" just because I can't cite the chapter and verse for those experiments.) Therefore, isn't it more the case that you must prove that red/blue shifts aren't the results of doppler shift rather than having to prove that they are?

/Ira


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: llanitedave]
      #5498974 - 11/01/12 07:24 AM

Quote:


The problem for me is that those who are insisting that a new physics of red shift is necessary to explain these anomalies have had some 30-odd years to propose some sort of physical mechanism for it. I've yet to see one that's even serious. Surely all the creative mathematical and physics-minded folks out there haven't been idle?




Dave,

I have afew thoughts regarding this.

1. de Ruiter et al.(1998)identified an interaction between two galaxy groups with a 4000 km s-1 redshift difference between the two groups (I linked to the ADS abstract earlier in the thread and you can download the paper). There has been exactly 2 citations of this paper - both by a researcher investigating anomalous redshifts. That's it - 2 citations in the 14 years since the result was published. Do you really think that a research community so completely uninterested in a 4000 km s-1 deviation from a smooth Hubble flow is going to devote any time to developing theoretical mechanisms to explain intrinsic redshifts - even given the 40+ years since Arp's first papers on the subject?

2. Narlikar&Arp (1993) proposed a variable mass hypothesis to explain intrinsic redshifts. In this model newly created matter has lower particle masses than matter that has been in existence longer. For a long time I wondered how the particles might aquire mass in this model. The recent discovery of the Higgs Boson makes me wonder if perhaps the physics involved in the particles gaining mass in the VMH might involve some sort of interaction with the Higgs Field. But I think before we can really know we would need a better understanding of the matter creation process Arp is proposing occurs in the cores of active galaxies.

3. With an army of particle physicists and astrophysicists, we've had ~30 years of searching for the elusive CDM particle. Nothing. Clearly a 30 year time frame is not a guarantee of discovering something that is actively being sought. So why would we expect it to be enough time to develop a theoretical mechanism to explain something that almost noone thinks is happening?

Dave


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Ira]
      #5498982 - 11/01/12 07:36 AM

Quote:

We can PROVE that objects in motion undergo a doppler shift. It's easy for sound. I assume it is also demonstrable for light. (I say "assume" just because I can't cite the chapter and verse for those experiments.) Therefore, isn't it more the case that you must prove that red/blue shifts aren't the results of doppler shift rather than having to prove that they are?

/Ira




Ira,

The situation is far more complicated than that. And really unless a person becomes very familiar with Arp's writing it is easy to misunderstand what is being claimed.

Arp does not deny the existence of doppler shifting as a factor affecting observed redshifts. For example, as I mentioned (and linked to earlier) spiral galaxy rotational velocities are measured by observing the doppler shifting that occurs across the disk of a galaxy. The side rotating toward our line of sight is blueshift relative to the nucleus and the side rotating away from our line of sight is redshifted relative to the nucleus.

Second, Arp in 1980 - and later papers- argued for instances where the redshifts of pairs of quasars he claimed are ejected from an active galaxy show doppler shifting relative to quantized peaks (see Arp&Hazard 1980). So he interpreted the redshift of the quasars as being mostly intrinsic, with a smaller doppler component superposed on the pair as one QSO was ejected toward us and the other was ejected away from us at ejection velocities of ~10000 km s-1 (which subsequently have turned out to be the approximate velocities that matter is often found moving outward from the "supermassive black holes" that supposedly reside in AGN).

Third, Arp does think that there is an underlying velocity-distance relationship that contributes a component of the redshift to all objects and is of the order described by a Hubble Constant of ~55-60 km s-1 Mpc-1.

Fourth - It is really about finding a mechansism that is capable of explaining intrinsic redshifts - not disproving other mechanisms. The mechanism would have to explain intrinsic redshifts in normal galaxies on the order of a few thousands of km s-1 on up through a dominant intrinsic redshift in quasars if Arp is correct that they are local.

Dave


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deSitter
Still in Old School


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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5499041 - 11/01/12 09:03 AM

Quote:

Quote:


The problem for me is that those who are insisting that a new physics of red shift is necessary to explain these anomalies have had some 30-odd years to propose some sort of physical mechanism for it. I've yet to see one that's even serious. Surely all the creative mathematical and physics-minded folks out there haven't been idle?




Dave,

I have afew thoughts regarding this.

1. de Ruiter et al.(1998)identified an interaction between two galaxy groups with a 4000 km s-1 redshift difference between the two groups (I linked to the ADS abstract earlier in the thread and you can download the paper). There has been exactly 2 citations of this paper - both by a researcher investigating anomalous redshifts. That's it - 2 citations in the 14 years since the result was published. Do you really think that a research community so completely uninterested in a 4000 km s-1 deviation from a smooth Hubble flow is going to devote any time to developing theoretical mechanisms to explain intrinsic redshifts - even given the 40+ years since Arp's first papers on the subject?

2. Narlikar&Arp (1993) proposed a variable mass hypothesis to explain intrinsic redshifts. In this model newly created matter has lower particle masses than matter that has been in existence longer. For a long time I wondered how the particles might aquire mass in this model. The recent discovery of the Higgs Boson makes me wonder if perhaps the physics involved in the particles gaining mass in the VMH might involve some sort of interaction with the Higgs Field. But I think before we can really know we would need a better understanding of the matter creation process Arp is proposing occurs in the cores of active galaxies.

3. With an army of particle physicists and astrophysicists, we've had ~30 years of searching for the elusive CDM particle. Nothing. Clearly a 30 year time frame is not a guarantee of discovering something that is actively being sought. So why would we expect it to be enough time to develop a theoretical mechanism to explain something that almost noone thinks is happening?

Dave




My own feeling - well it's more than that, at the risk of appearing arrogant I have a worked-out field theory - is that what we are seeing is the effect of unification of gravitation and electromagnetism. From this point of view, every gravitational field also generates an electromagnetic field. For normal objects the difference in strength of 10^39 renders this moot, but for the entire universe, and for extremely condensed objects, it becomes important. Thus the whole universe carries a small temperature, which of course is the CMB. What should be looked for in these possibly intrinsically redshifted objects is line broadening coming from the fact that some regions are more redshifted than others by dint of the ambient field conditions. Seeing this would require a source of some considerable size. A typical AGN nucleus or quasar is probably not extended enough.

-drl


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deSitter
Still in Old School


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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5499996 - 11/01/12 09:46 PM

Quote:

In looking over a variety of images of the NGC7603 pair, I see no compelling reason to think the 'bridge' is nothing more than one of the larger object's spiral arms, which by chance happens to terminate at the smaller object. If such a bridge is the result of tidal stripping of stars from the interloper, there should be an 'anti-tail' of length at least some small fraction of that of the tail apparent here. If the 'bridge' is a spiral arm of the larger galaxy, it does not seem to be warped or distorted to any notable degree.

The high redshift 'knots' could well be background objects, too.




So, there is an association of two galaxies that are apparently connected by a bridge of material - but not so, because it's a chance alignment, so that material bridge is "a bridge to nowhere" like in Alaska. OK fine. But on the bridge to nowhere, there are two apparent elks dressed in extreme red, but they also are not really elks on the bridge, they are Giant Red Yetis on the distant hillside who just happen to be standing in exactly the right place so that they appear to be dead on the bridge to nowhere. So we have four complete coincidences - a bridge to nowhere (never seen), a distant hill that just happens to line up exactly with the real end of the bridge, and two distant Giant Red Yetis that just by sheer coincidence happen to appear to be standing on the bridge, even though they are 10 times farther away.

Do you now see that this is basically impossible? Thinking this way is not a defense of science - it is a refusal to accept the plain evidence of your own eyes.

-drl


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llanitedave
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5500185 - 11/01/12 11:44 PM

Quote:

Quote:

Quote:


The problem for me is that those who are insisting that a new physics of red shift is necessary to explain these anomalies have had some 30-odd years to propose some sort of physical mechanism for it. I've yet to see one that's even serious. Surely all the creative mathematical and physics-minded folks out there haven't been idle?




Dave,

I have afew thoughts regarding this.

1. de Ruiter et al.(1998)identified an interaction between two galaxy groups with a 4000 km s-1 redshift difference between the two groups (I linked to the ADS abstract earlier in the thread and you can download the paper). There has been exactly 2 citations of this paper - both by a researcher investigating anomalous redshifts. That's it - 2 citations in the 14 years since the result was published. Do you really think that a research community so completely uninterested in a 4000 km s-1 deviation from a smooth Hubble flow is going to devote any time to developing theoretical mechanisms to explain intrinsic redshifts - even given the 40+ years since Arp's first papers on the subject?

2. Narlikar&Arp (1993) proposed a variable mass hypothesis to explain intrinsic redshifts. In this model newly created matter has lower particle masses than matter that has been in existence longer. For a long time I wondered how the particles might aquire mass in this model. The recent discovery of the Higgs Boson makes me wonder if perhaps the physics involved in the particles gaining mass in the VMH might involve some sort of interaction with the Higgs Field. But I think before we can really know we would need a better understanding of the matter creation process Arp is proposing occurs in the cores of active galaxies.

3. With an army of particle physicists and astrophysicists, we've had ~30 years of searching for the elusive CDM particle. Nothing. Clearly a 30 year time frame is not a guarantee of discovering something that is actively being sought. So why would we expect it to be enough time to develop a theoretical mechanism to explain something that almost noone thinks is happening?

Dave




My own feeling - well it's more than that, at the risk of appearing arrogant I have a worked-out field theory - is that what we are seeing is the effect of unification of gravitation and electromagnetism. From this point of view, every gravitational field also generates an electromagnetic field. For normal objects the difference in strength of 10^39 renders this moot, but for the entire universe, and for extremely condensed objects, it becomes important. Thus the whole universe carries a small temperature, which of course is the CMB. What should be looked for in these possibly intrinsically redshifted objects is line broadening coming from the fact that some regions are more redshifted than others by dint of the ambient field conditions. Seeing this would require a source of some considerable size. A typical AGN nucleus or quasar is probably not extended enough.

-drl




Danny, I'm a very long way from being qualified to give your theoretical approach any kind of critical evaluation. I can't go any further than to say I've read your paper, and my gut feeling about it is that you may indeed be on to something. And I sincerely hope that it turns out to be correct.

On the assumption that it is, doesn't it give you the ability to analyze those anomalous systems and make some testable physical predictions about them?

I definitely don't like Harp's arguments about matter having a variable mass -- if that were the case I don't think those odd galaxies would be able to form stars at all, much less populate them with familiar stellar types.

So what if you were to focus your theory on some of these discrepancies? What, exactly, would those red shifts tell us?


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: llanitedave]
      #5500435 - 11/02/12 06:00 AM

Between work and other survival activities, I work on just this, and will publish when it's time The equations are beastly hard to solve and make GR look like freshman physics. But there are solutions! which is good to know.

The key problem is to set the scale of EM vs gravity from observation of the CMB. That will enable a prediction of what happens in a condensed object. That's my goal.

-drl


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GlennLeDrew
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5500982 - 11/02/12 01:37 PM

Danny,
I fully realize that at face value three coincidental occurrences in the NGC 7603 system would be taken as a most remote possibility; they being the connecting bridge, and the two knots on that bridge.


I still see the bridge as merely a spiral arm, whose form is not so different from its counterpart on the other side of the large galaxy. If the result of an encounter between two galaxies (even when a considerable disparity in mass exists), such a neat, prominent, single, *connecting* bridge, in the absence of other more extensive tidal debris, seems just too unnatural to me.

In a Hubble image, the two 'knots' appear to me like very distant spiral systems, coincidentally superimposed on the 'bridge.' Actually, they seem to be displaced somewhat on the concave side of the bridge mid-line. If this displacement is more than just my visual impression, it must at least raise questions as to the strength of connection. Why should such well-defined concentrations not lie on the bridge mid-line if they are part of it?

As to the coincidental alignment of two distant galaxies upon the spiral arm of a foreground system. Why should this be dismissed? Could not this be one of the very few cases which statistics allows? Has anyone determined the Poission (is that the right term?) distribution on the sky of similarly redshifted objects? Can we so confidently reject out of hand such a coincidental alignment and thereby have to invoke a new Physics?

Extraordinary claims require extraordinary evidence. In this case I thus far see nothing which cannot be explained by line-of-sight projection. Ad coincidental as it undoubtedly is.


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: GlennLeDrew]
      #5501224 - 11/02/12 04:43 PM

Quote:


I still see the bridge as merely a spiral arm, whose form is not so different from its counterpart on the other side of the large galaxy.




Glenn,

I hope you don't mind me jumping in again on this as I know you were replying to Danny. And let me say first that I genuinely appreciate the respectful nature of all of you engaging in this discussion. I discussed this topic at length years ago on another forum and there were a lot of rude responses. It is nice to have a reasoned discussion.

Regarding the "bridge" or "arm" that makes the apparent connection: I would say that this particular structure is rather unusual. Here is a link with one of the most detailed images of this galaxy:

http://homepage.eircom.net/~gracedieu/Observatory.htm

I don't see any obvious counter structure. If you remove this "bridge" both sides of the galaxy have a bright disk with an extended more diffuse patchy disk.

I took another look at the images of this galaxy on the IRSA Image database which compiles images from SDSS, the digitized sky survey (DSS - which includes B, R, and IR band images), and 2MASS. The "bridge" shows clearly in all SDSS and DSS images and no counter structure shows up in those images.

You can search the images here:

http://irsa.ipac.caltech.edu/applications/FinderChart/

Click "reproject" to get higher resolution images.

Quote:

If the result of an encounter between two galaxies (even when a considerable disparity in mass exists), such a neat, prominent, single, *connecting* bridge, in the absence of other more extensive tidal debris, seems just too unnatural to me.




That is why I think Arp's ejection/intrinsic redshift scenario is more plausible than tidal interaction. Obviously the chance alignment option is possible too.

Quote:

In a Hubble image, the two 'knots' appear to me like very distant spiral systems, coincidentally superimposed on the 'bridge.' Actually, they seem to be displaced somewhat on the concave side of the bridge mid-line. If this displacement is more than just my visual impression, it must at least raise questions as to the strength of connection. Why should such well-defined concentrations not lie on the bridge mid-line if they are part of it?




I don't think there is any reason they should be exactly on the mid-line. Lopez-Corredoira and Gutierrez discuss this and they are slightly off center from the mid-line. But they are clearly projected within the bridge. That doesn't prove interaction, but I think once again the arrangement is consistent with an ejection scenario and not an interloper interaction scenario.

Quote:

As to the coincidental alignment of two distant galaxies upon the spiral arm of a foreground system. Why should this be dismissed? Could not this be one of the very few cases which statistics allows? Has anyone determined the Poission (is that the right term?) distribution on the sky of similarly redshifted objects? Can we so confidently reject out of hand such a coincidental alignment and thereby have to invoke a new Physics?

Extraordinary claims require extraordinary evidence. In this case I thus far see nothing which cannot be explained by line-of-sight projection. Ad coincidental as it undoubtedly is.




It is a very coincidental alignment. The calculation actually was done. Here is the paper:

http://adsabs.harvard.edu/abs/2004A%26A...421..407L

It comes out to a 3 in a billion chance that this is an accidental arrangement. The paper also discusses the spectral characteristics of these galaxies. The are HII galaxies with spectral characteristics of dwarf galaxies.

Dave


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: llanitedave]
      #5501235 - 11/02/12 04:52 PM

Quote:


I definitely don't like Harp's arguments about matter having a variable mass -- if that were the case I don't think those odd galaxies would be able to form stars at all, much less populate them with familiar stellar types.




But you really don't know until the full details of the theory and the underlying mechanism are worked out.

On page 109 of Seeing Red Arp presents a Table that provides age differences for galaxies with varying amounts of intrinsic redshift. These values are derived from the Narlikar&Arp model.

The NGC 7603 companion galaxy would be 670 million years younger than the main galaxy in this model. Of course this explanation is not without its own problems. Certainly we need to ask if the companion is less than a billion years younger then how is it the bridge is still present after billions of years of rotation.

In any case these are the sorts of details that need to be fully worked out before the idea can be disproven. We don't know that stars cannot form as newly created matter evolves and particles gain mass (again if Arp is right). I think so much of this depends upon the exact mechanism by which the initially zero-mass particles aquire mass.

Dave


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Ira
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5502381 - 11/03/12 12:58 PM

Geez, with all the image analysis SW around these days you'd think someone could do better than just eyeball a photo and give their opinion of it.

/Ira


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Ira]
      #5502434 - 11/03/12 01:45 PM

There are people over on the imaging forums who are perfectly capable of making very deep images of this galaxy to get a better view at least of the morphology.

Here's another very interesting case because there is little doubt that the two objects are adjacent - the star-forming knots are identical in size and shape:

http://en.wikipedia.org/wiki/NGC_1232

NED 1232
http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+1232
Red shift distance 95 million LY

NED 1232A
http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+1232A
Red shift distance 390 million LY

-drl


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5502443 - 11/03/12 01:50 PM

Idea - these spirals start out as spindles with matter spewing from one or both ends - as they evolve and spin through space the ejected material assumes a spiral pattern like a Catherine wheel firework.

-drl


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Ira]
      #5502479 - 11/03/12 02:25 PM

Quote:

Geez, with all the image analysis SW around these days you'd think someone could do better than just eyeball a photo and give their opinion of it.

/Ira




I think one thing that has happened over the years is that people have come to believe incorrectly that "eyeball" inspection of images is always inferior to computer algorithms. I've found that visually inspecting the DSS image of each galaxy in samples I've worked with makes it possible to identify galaxies with large errors in the data and reduce scatter in the analysis.

Here is one example:

http://cseligman.com/text/atlas/ngc25a.htm#2582

The galaxy in this image is NGC 2582. For galaxies an inclination of 90 degrees is edge on and an inclination of 0 degrees is face on. NGC 2582 is clearly very close to face on orientation from a visual inspection of the image. Yet several papers have published it's inclination as 51 degrees - which is incorrect and results in calculated distances that are significantly in error until a closer to face on orientation for this galaxy is applied to the data.

My point is that software has its uses, equations have their uses, but for many applications you still need to visually inspect images as a sanity check on the algorithm generated results.

I don't feel a software program is going to resolve this particular debate.

Dave


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russell23
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5502524 - 11/03/12 02:51 PM

Quote:

There are people over on the imaging forums who are perfectly capable of making very deep images of this galaxy to get a better view at least of the morphology.

Here's another very interesting case because there is little doubt that the two objects are adjacent - the star-forming knots are identical in size and shape:

http://en.wikipedia.org/wiki/NGC_1232

NED 1232
http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+1232
Red shift distance 95 million LY

NED 1232A
http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+1232A
Red shift distance 390 million LY

-drl




And you can add to this analysis. The companion galaxy is NGC 1232A and is morphologically an SBm type dwarf spiral. There are 12 of these galaxies with either Cepheid distances or in the Virgo cluster and Ursa Major cluster and with measured B-band isophotal diameters. The 12 SBm galaxies in question have a typical linear diamter of 6.8 +/- 3.5 kiloparsecs (kpc) with a range of 2.7kpc to 13.1kpc.

NGC 1232A would have a linear diamter of 23.3 kpc at its Hubble distance which then is 4.7 standard deviations above the mean. NGC 1232 has a distance of 17.4 Mpc from the Tully-Fisher relation. At this distance NGC 1232A would have a diameter of 4.4 kpc which falls nicely in the range of diameters for local SBm galaxies.

The same argument can be applied to the absolute magnitude of this galaxy. At the Hubble distance the absolute magnitude of NGC 1232A is -19.72 (B-band magnitude) - which is what is expected for a moderate sized spiral of Sa, Sb, and Sc types and is much too luminous for an SBm type spiral. A the NGC 1232 Tully-Fisher distance NGC 1232A would have an absolute magnitude of -16.10 which is in the normal range for dwarf galaxies such as SBm spirals.

Dave


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Neutrino?
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: deSitter]
      #5503038 - 11/03/12 09:27 PM

Quote:

Between work and other survival activities, I work on just this, and will publish when it's time The equations are beastly hard to solve and make GR look like freshman physics. But there are solutions! which is good to know.

The key problem is to set the scale of EM vs gravity from observation of the CMB. That will enable a prediction of what happens in a condensed object. That's my goal.

-drl




Where's the psuedo-Dirac eq paper? It's not available.


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: Neutrino?]
      #5503238 - 11/04/12 12:29 AM

It had an argument that I realized was wrong. Repairs in progress.

-drl


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deSitter
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5503596 - 11/04/12 09:08 AM

Quote:

Quote:

There are people over on the imaging forums who are perfectly capable of making very deep images of this galaxy to get a better view at least of the morphology.

Here's another very interesting case because there is little doubt that the two objects are adjacent - the star-forming knots are identical in size and shape:

http://en.wikipedia.org/wiki/NGC_1232

NED 1232
http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+1232
Red shift distance 95 million LY

NED 1232A
http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+1232A
Red shift distance 390 million LY

-drl




And you can add to this analysis. The companion galaxy is NGC 1232A and is morphologically an SBm type dwarf spiral. There are 12 of these galaxies with either Cepheid distances or in the Virgo cluster and Ursa Major cluster and with measured B-band isophotal diameters. The 12 SBm galaxies in question have a typical linear diamter of 6.8 +/- 3.5 kiloparsecs (kpc) with a range of 2.7kpc to 13.1kpc.

NGC 1232A would have a linear diamter of 23.3 kpc at its Hubble distance which then is 4.7 standard deviations above the mean. NGC 1232 has a distance of 17.4 Mpc from the Tully-Fisher relation. At this distance NGC 1232A would have a diameter of 4.4 kpc which falls nicely in the range of diameters for local SBm galaxies.

The same argument can be applied to the absolute magnitude of this galaxy. At the Hubble distance the absolute magnitude of NGC 1232A is -19.72 (B-band magnitude) - which is what is expected for a moderate sized spiral of Sa, Sb, and Sc types and is much too luminous for an SBm type spiral. A the NGC 1232 Tully-Fisher distance NGC 1232A would have an absolute magnitude of -16.10 which is in the normal range for dwarf galaxies such as SBm spirals.

Dave




Yes, very excellent point.

Here's a larger image - look below the galaxy - there are strange red spindles everywhere, some well defined, some just emerging. There is one embedded in the galaxy itself at about the 2-o'clock position, coincident with a thick dust lane. There are several dwarfs to the left which are of the spindle type with one small tendril emerging from either end. One always sees these spindles in the vicinity of active galaxies.

http://www.robgendlerastropics.com/NGC1232-Subaru-ESO-L.jpg

-drl


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BillFerris
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Re: Red/Blue shift due to Doppler effect = assumption? new [Re: russell23]
      #5503717 - 11/04/12 10:45 AM

As points of reference, in his 1988 publication, Nearby Galaxies Catalog, Tully includes distances of 20.0 megaparsecs (Mpc) and 21.1 megasparsecs, respectively, for NGC 1232 and NGC 1232A. The respective distance modulus data for these galaxies are 31.50 Mpc (N1232) and 31.62 Mpc (N1232A).

Bill in Flag


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