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A unified theory of cataclysmic variable evolution...

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#1 BillP

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Posted 24 March 2020 - 07:33 PM

I find cataclysmic variables intensely interesting.  Here's some new developments on that front...

 

Article - https://phys.org/new...ae-iceberg.html

 

Paper - https://arxiv.org/ft.../2001.05025.pdf


Edited by BillP, 24 March 2020 - 07:33 PM.

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#2 Astrola72

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Posted 24 March 2020 - 07:46 PM

Never heard of that, but fascinating. Thanks!

 

Joe



#3 BQ Octantis

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Posted 24 March 2020 - 09:31 PM

I didn't realize it was a controversial, unproven theory. I was just reading about these a few days ago as I learned more about the Type II supernova that created the Vela Supernova Remnant I captured. In this article in particular, written in 2014 (6 years ago now!), the author (Dr. David Taylor, professor of physics and astronomy at Northwestern University) describes them matter-of-factly as commonplace in the universe.

 

"Just like the core of a star undergoing a helium flash, the electron-degenerate hydrogen on the white dwarf cannot expand and cool.  So, the trapped heat from the fusing hydrogen only acts to make the reaction run even faster, and before you can say 'hydrogen flash', a nuclear firestorm engulfs the entire star.  Like a planet with a gasoline ocean, the white dwarf instantly goes up in (nuclear fusion) flames.  For weeks the nuclear inferno burns, with the dwarf spectacularly leaping to a luminosity 100,000 times that of the Sun.  Such events are called novas, from the Latin for 'new', because as seen from Earth they appear to be new stars that have suddenly appeared.  (It is from novas that we get the name for their even larger cousins, the supernovas.)  Novas are surprisingly common, because unlike supernovas the delivery truck that brings them doesn't blow itself up at the end of the run.  Once the firestorm has run its course, the white dwarf is virtually unaffected and the only sign left of the nova is a small, expanding shell of hot gas.  The gas is the "ashes" of the hydrogen ocean, finally heated to the point where it could escape.  But the red giant is still out there, and its atmosphere is still swirling down on the dwarf, so the whole process begins again.  Depending on the exact parameters of the system, red giant / white dwarf doubles can explode a thousand times like this over several million years."

 

Then again, he has a telling quote that perhaps sheds light on the novelty of the simulation you referenced:

 

"Copious bursts of X-rays and hard ultraviolet radiation pour from the roiling gasses, providing nearly unlimited raw material for PhD theses in astrophysics."

 

And one more:

 

"To the delight of astronomers everywhere, there are so many pathways that a double system can take at this point that we could probably keep everybody in the astro-business employed for the next twenty years just by working out the details.  Very subtle factors, including their exact separation, the precise masses of the two stars, the eccentricity of their orbit, their rotation rates, and even the strengths of their magnetic fields, can lead to dramatic changes in how the stars interact."

 

So we've got another 14 years of these papers to go!

 

BQ



#4 BillP

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Posted 25 March 2020 - 07:52 PM

I doubt most of out "theories" are correct.  They are correct based on what we see with remote long range sensing, but that is not enough.  Jupiter is a good lesson.  NASA says that until the Juno probe got there, most everything we theorized about Jupiter was wrong:  "Before NASA sent its Juno spacecraft to explore Jupiter, astronomers were "totally wrong" about much of what they thought they knew about the planet, the mission's principal investigator, Scott Bolton, said during a lecture here at the 231st meeting of the American Astronomical Society on Tuesday (Jan. 9)." 

 

And that is for a celestial object right next door!  Doubt anything we think really reflects the true situation.  But it makes us feel good to think we have figured things out. LOL

 

https://www.space.co...evelations.html



#5 BQ Octantis

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Posted 25 March 2020 - 09:08 PM

I doubt most of out "theories" are correct.  They are correct based on what we see with remote long range sensing, but that is not enough.  Jupiter is a good lesson.  NASA says that until the Juno probe got there, most everything we theorized about Jupiter was wrong:  "Before NASA sent its Juno spacecraft to explore Jupiter, astronomers were "totally wrong" about much of what they thought they knew about the planet, the mission's principal investigator, Scott Bolton, said during a lecture here at the 231st meeting of the American Astronomical Society on Tuesday (Jan. 9)." 

 

And that is for a celestial object right next door!  Doubt anything we think really reflects the true situation.  But it makes us feel good to think we have figured things out. LOL

I've felt that way about cosmology for a long, long time (though far less than my entire lifetime). By its very nature, it's only an observational science (it's kind of hard to make a black hole in the lab!). But George Box's quote seems in order here:

 

"All models are wrong, but some are useful."

 

For Jupiter, most of what we knew about the planet before Juno came from Voyager; before that, we were lucky that the Copernican model stopped us from having to sacrifice oxen to prevent it from going wherever we didn't want it (or negatively influencing our lives when it did!—wait, is Mercury currently in retrograde?…).

 

As for the model of a white dwarf cataclysmic binary, besides the newly minted PhDs (who at least were fed while they were in school), we can sleep in comfort knowing that our sun won't suffer the same fate. At least not in our lifetimes…

 

BQ


Edited by BQ Octantis, 25 March 2020 - 10:47 PM.


#6 llanitedave

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Posted 25 March 2020 - 09:49 PM

"Totally wrong" is probably a bit of hyperbole.  But we expected from the very beginning that Juno would uncover a lot of new things, and correct a lot of misconceptions.  That's why we built the dang thing!  Not because we thought we had it all figured out, but because we knew we didn't!


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#7 BillP

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Posted 25 March 2020 - 10:25 PM

"Totally wrong" is probably a bit of hyperbole.

 

You know, if you purchased a car and it arrived without a drive train, missing 2 tires, no seats inside, and a missing gas tank, saying it was "totally wrong" would be hyperbole as well lol.gif  

 

Is there really a difference between totally wrong and mostly or just wrong?  They are all wrong afterall.  But wait -- https://www.youtube....h?v=SamgviMdxes



#8 llanitedave

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Posted 26 March 2020 - 10:34 AM

You know, if you purchased a car and it arrived without a drive train, missing 2 tires, no seats inside, and a missing gas tank, saying it was "totally wrong" would be hyperbole as well lol.gif  

 

Is there really a difference between totally wrong and mostly or just wrong?  They are all wrong afterall.  But wait -- https://www.youtube....h?v=SamgviMdxes

Of course there's a big difference between wrongs.  Did you ever read Isaac Asimov's essay on The Relativity of Wrong?  I'd be surprised if you haven't.  But even if you have, I'm surprised it didn't have an impact in your thinking.

 

Modern medicine is often wrong.  Is there a difference between that and the wrongness of medieval medicine?  Hint:  the fact that I'm alive today implies there's a big difference.

 

Jupiter was never advertised as a complete car for purchase.  Since the beginning of the scientific age it's been viewed as an object of mystery, one that cries out for more exploration.

So yeah, hyperbole big time.


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#9 BQ Octantis

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Posted 01 April 2020 - 12:39 AM

Unexpectedly enough, I just discovered I captured an eruption of a cataclysmic binary in the Carina Nebula that ignited back in '18:

 

post-273658-0-58408700-1585652549.gif

 

Fortunately, I had read and responded to this article several weeks before…so I slept soundly knowing happened!

 

BQ


Edited by BQ Octantis, 01 April 2020 - 12:42 AM.

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#10 BillP

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Posted 06 April 2020 - 01:28 PM

Of course there's a big difference between wrongs.  Did you ever read Isaac Asimov's essay on The Relativity of Wrong?  I'd be surprised if you haven't.  But even if you have, I'm surprised it didn't have an impact in your thinking.

 

Modern medicine is often wrong.  Is there a difference between that and the wrongness of medieval medicine?  Hint:  the fact that I'm alive today implies there's a big difference.

 

 

Your hint is not causal.  My opinion is not changed by the Asimov argument at all because a matter of degrees is not really relevant.  Being less wrong or being more wrong are both being wrong.  So no big difference (except for those trying to feel good about their being less wrong lol.gif ).  I will give no one a medal for being "less" wrong!  The big issue relative to science, is people more often demonstrate a strange level of almost "worship" of it.  This then leads to very clear arrogance and bias in their thinking, negating much of the benefit of the methoology.  Science is not automatically "right".  People who use the method are no better at being right in their conclusions than those who do not wield it.  Basically humans make mistakes or introduce confounding biases just as much in any endeavor they do.  IMO it is better to recognize always when one makes a claim based on scientific methods or otherwise, that they can only be correct up to the point of the data they examined, and that they can never know if the data they have on hand is sufficient to be mostly right, or not nearly right.  So they need to keep a healthy amount of humility understating both their limitations and their flaws, and the limitations and flaws in the methods they use, for which the scientific method clearly has in abundance.

 

And back to the hint, that is a common response, especially when you ask those in medicine who of course have that bias.  Historians though provide another view.  Clean water, clean food, proper harvesting and storage of food, proper waste disposal, safe and protected living conditions, and most of all reduction of poverty, those are what have driven life expectancy.  It's not that medicine did nothing in this regard, but it has not done the lion's share by any means compared to living more cleanly and being well fed.  So prevention has trumped intervention by a much larger degree.
 



#11 BillP

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Posted 06 April 2020 - 01:29 PM

Unexpectedly enough, I just discovered I captured an eruption of a cataclysmic binary in the Carina Nebula that ignited back in '18

 

That is fantastic!!!  bow.gif



#12 BQ Octantis

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Posted 06 April 2020 - 06:28 PM

That is fantastic!!!  bow.gif

Thanks Bill! The progenetor star was magnitude 20.1; I put the flash at magnitude 5.1 (in comparison to the neighbor star t1 Car). Since visual magnitude is the 2.5 times the log (base 10) of the ratio, this would be an increase in brightness by a factor of 1,000,000! And two years later, its remnant at magnitude 11.7 is still over 2000 times brighter than when it started…

 

BQ



#13 llanitedave

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Posted 06 April 2020 - 07:23 PM

Your hint is not causal.  My opinion is not changed by the Asimov argument at all because a matter of degrees is not really relevant.  Being less wrong or being more wrong are both being wrong.  So no big difference (except for those trying to feel good about their being less wrong lol.gif ).  I will give no one a medal for being "less" wrong!  The big issue relative to science, is people more often demonstrate a strange level of almost "worship" of it.  This then leads to very clear arrogance and bias in their thinking, negating much of the benefit of the methoology.  Science is not automatically "right".  People who use the method are no better at being right in their conclusions than those who do not wield it.  Basically humans make mistakes or introduce confounding biases just as much in any endeavor they do.  IMO it is better to recognize always when one makes a claim based on scientific methods or otherwise, that they can only be correct up to the point of the data they examined, and that they can never know if the data they have on hand is sufficient to be mostly right, or not nearly right.  So they need to keep a healthy amount of humility understating both their limitations and their flaws, and the limitations and flaws in the methods they use, for which the scientific method clearly has in abundance.

 

And back to the hint, that is a common response, especially when you ask those in medicine who of course have that bias.  Historians though provide another view.  Clean water, clean food, proper harvesting and storage of food, proper waste disposal, safe and protected living conditions, and most of all reduction of poverty, those are what have driven life expectancy.  It's not that medicine did nothing in this regard, but it has not done the lion's share by any means compared to living more cleanly and being well fed.  So prevention has trumped intervention by a much larger degree.
 

Well, with that kind of black and white view of the world, Bill, there's never anything to debate.  Anything you say, all I have to do is wave my hand and say  "You're wrong!" 

 

If nobody's 100% right, then they're all wrong.

 

Seems a bit like going to extremes.


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