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Unique Binary Globular Cluster Delivered By The Sagittarius Dwarf Spheroidal Galaxy, M53 and NGC5053

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#1 rekokich

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Posted 01 February 2022 - 02:16 PM

It is irresistible to imagine the environment within a tightly organized globular cluster. The night sky would be sublime with a million visible stars, and a bird's-eye view of the entire Milky Way galaxy. How much earlier would astronomy and associated technology develop among an intelligent species living on a world graced with such inspiration? Unfortunately, complex life in globular clusters is extremely unlikely due to virtual absence of heavier elements. It is not even known if rocky planets can form in that environment. Therefore, such spectacles are probably unseen by intelligent eyes, and must remain confined to our imagination.

Click here to view the article
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#2 Rustler46

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Posted 01 February 2022 - 02:58 PM

Fascinating and informative article. I've yet to read the entire paper. But will do so as time allows. Personally I've been aware of the pair for quite some time. But my record of observations of NGC 5053 shows only two instances of that cluster. The first one was in 1968 with my 8-inch RFT reflector and another in 2017 with a C-11 - some 49 years apart. In contrast M53 has 16 records, none of which mention seeing NGC 5053 in the vicinity. 

 

A quote from the article describing some aspects of NGC 5053 may explain why I haven't observed this globular very many times:

  • Its angular size is 10.5 arcmin, integrated apparent magnitude 9.96 (V), and estimated heliocentric distance 53,500 ly, receding at 43 km/sec. Its brightest red giant stars are of apparent magnitude 14, and horizontal-branch stars average around 16.7. While it is accessible to small apertures photographically, substantial telescopes are required for visual observation.

But based on the fact that this pair is unique among Milky Way globulars will make it another target in 2022. It is high time for me to further investigate this fascinating duo of globulars. With increasing light pollution, this may be difficult except from my B-2 dark-sky observing site, about 1-1/2 hours travel time from home with B-5 skies.

 

Russ


Edited by Rustler46, 01 February 2022 - 03:37 PM.

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#3 raa

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Posted 01 February 2022 - 06:44 PM

It is irresistible to imagine the environment within a tightly organized globular cluster. The night sky would be sublime with a million visible stars, and a bird's-eye view of the entire Milky Way galaxy. How much earlier would astronomy and associated technology develop among an intelligent species living on a world graced with such inspiration? Unfortunately, complex life in globular clusters is extremely unlikely due to virtual absence of heavier elements. It is not even known if rocky planets can form in that environment. Therefore, such spectacles are probably unseen by intelligent eyes, and must remain confined to our imagination.

Click here to view the article

It is irresistible to imagine the environment within a tightly organized globular cluster - Nightfall, by Isaac Asimov.

 

Metallicity might not be the issue.  Dynamics will.  Planets would have a good chance of either being slung out or slung into a star, just as stars are, hence in stellar terms :- blue stragglers (merged binaries), pulsars and millsecond pulsars, even the odd cataclysmic variable, on the slung in side (although in some cases, rotationally sped up), and possibly some aspects of globular cluster streams, however that is thought to be primarily due to tidal interaction with the Milky Way.


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#4 MartinMeredith

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Posted 02 February 2022 - 05:24 AM

Fascinating article.

 

I wonder also about any physical relationship between the pair NGC 6528 and 6522, less than 30' apart and with a similar estimated distance ~ 25klyr.  At a declination of -30 they're not that accessible for northern observers, but I observed these photographically back in 2020 and there is something remarkable about seeing two globs quite so close. 

 

Martin


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#5 David Knisely

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Posted 02 February 2022 - 10:38 AM

Yea, while I have been able to fairly easily show a rich mass of stars in M53 in my 8 and 10 inch scopes, NGC 5053 is another story.  At best using very high power, only maybe 40 individual stars were visible in my 9.25 inch SCT, and even in my 14 inch f/4.6 Newtonian, that number only increased to somewhere between 50 and 100 stars, as the component stars are quite faint making judging exactly how many are actually visible somewhat difficult.  Both objects are fairly easy to see in modest apertures and it is nice to know that they may indeed be physically related.  Clear skies to you.   


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#6 ButterFly

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Posted 02 February 2022 - 08:27 PM

5053 likes very stable seeing to resolve with my 15".  When it does, it's a diamond dust of stars on a hazy background.  My altitude helps.

 

I was certainly shocked the first time I looked up their distances.



#7 David Knisely

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Posted 02 February 2022 - 11:19 PM

5053 likes very stable seeing to resolve with my 15".  When it does, it's a diamond dust of stars on a hazy background.  My altitude helps.

 

I was certainly shocked the first time I looked up their distances.

Yea, even Luginbuhl & Skiff in OBSERVING HANDBOOK AND CATALOGUE OF DEEP-SKY OBJECTS only says "With a 25 cm a few stars are resolved at medium power, while a 30 cm will resolve about 30 faint stars overlying a 5' arc area."  With around 40 stars counted, I guess I did a little better with my 9.25 inch SCT.  In Megastar's thumbnail image of the cluster, I can easily count around 100 stars with good prominent star images that stand out from the more granular background of the many many fainter ones.  The cluster is listed with giant branch tip magnitude (V(tip)) of 13.8 and a horizontal branch magnitude of 16.7, so the component stars are definitely fairly faint (in other words, it sure ain't M13 smile.gif).  Clear skies to you.


Edited by David Knisely, 02 February 2022 - 11:21 PM.

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#8 Rasfahan

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Posted 03 February 2022 - 06:54 AM

Thank you for this interestjng article!


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#9 brentelgeuse

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Posted 03 February 2022 - 09:19 PM

Your article serves as a motivation to observe these objects.

 

This inter-galactic couple, forever wed in aeons-long waltz through a sea of motes, of tiny glimmers, carry inexorably across our skies. Each dances on the strings of that despotic uncaring master, condemned to observe each the other from afar, without touch or embrace, except in the ablation of slow death. Oh! incomprehensible powerful assemblages, you blaze with the stuff of the Universe, your path yearns for these swaddling lacteal bands like a lover's bed. 

 

Everything we are and ever will be is a mist. Humanity's color blossoms, then fades before your irreverent and unseeing eyes a million strong, long before the finish of your first turn in this cosmic choreography. Your far, far light touches our nights and fires our minds with what is and our nacent imaginings with what could be. Yet these terrestrially bound observers, these self-important puny bits of spent star stuff, so transient so slight, cast a casual glance and say, faint smudges and nothing more.


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#10 lwbehney

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Posted 03 February 2022 - 11:17 PM

I hope someone can answer a question regarding the metallicity affecting when a star leaves the main sequence. I would assume a higher metallicity star would have a denser and hotter core and would have a shorter life span, yet apparently the opposite is true. Do larger atoms in the core disrupt the rate of hydrogen fusion?

What is the mechanism by which this difference in metallicity causes a variation in stellar  luminosity and in fusion rates?

  I would also like to know from whence all these dwarf galaxies are cruising by our galaxy such as the LMC and SMC?

Thanks for this really cool review article.

-Larry



#11 rekokich

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Posted 04 February 2022 - 05:14 AM

Your article serves as a motivation to observe these objects.

 

This inter-galactic couple, forever wed in aeons-long waltz through a sea of motes, of tiny glimmers, carry inexorably across our skies. Each dances on the strings of that despotic uncaring master, condemned to observe each the other from afar, without touch or embrace, except in the ablation of slow death. Oh! incomprehensible powerful assemblages, you blaze with the stuff of the Universe, your path yearns for these swaddling lacteal bands like a lover's bed. 

 

Everything we are and ever will be is a mist. Humanity's color blossoms, then fades before your irreverent and unseeing eyes a million strong, long before the finish of your first turn in this cosmic choreography. Your far, far light touches our nights and fires our minds with what is and our nacent imaginings with what could be. Yet these terrestrially bound observers, these self-important puny bits of spent star stuff, so transient so slight, cast a casual glance and say, faint smudges and nothing more.

Globular clusters are gifted with size and a blaze of starlight, and we puny humans with intellect and inspiration.

Thank you.
 


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#12 rekokich

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Posted 04 February 2022 - 06:45 AM

I hope someone can answer a question regarding the metallicity affecting when a star leaves the main sequence. I would assume a higher metallicity star would have a denser and hotter core and would have a shorter life span, yet apparently the opposite is true. Do larger atoms in the core disrupt the rate of hydrogen fusion?

What is the mechanism by which this difference in metallicity causes a variation in stellar  luminosity and in fusion rates?

  I would also like to know from whence all these dwarf galaxies are cruising by our galaxy such as the LMC and SMC?

Thanks for this really cool review article.

-Larry

Larry,

As Fig.5 in the article suggests, given equal mass, stars of low metallicity burn hotter, and turn toward the red giant stage sooner. Your explanation is probably correct, that in high metallicity stars larger (and inert) atomic nuclei come between hydrogen nuclei, and inhibit their fusion.

As for the origin of dwarf galaxies, the Universe is plausably strewn with trillions of dwarf galaxies which are presently undetectable at a distance due to low mass and luminosity. You might be interested to read about the Faint Blue Galaxies (FBG) here
https://www.cloudyni...diversity-r3265
These are dwarf iregular galaxies presently undergoing starburst activity in the field for undetermined reasons. They are the most numerous galaxy type on Hubble images. Is it possible that low luminosity dwarf galaxies without starburst activity might be an order of magnitude more numerous? The answer might be revealed when the James Webb telescope sheds infrared light on the subject.


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#13 fallenstarseven

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Posted 04 February 2022 - 04:18 PM

I'll join the bandwagon and look for this pair in 2022.  This article was a true pleasure to read, thanks for sharing it.


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#14 ButterFly

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Posted 04 February 2022 - 04:19 PM

I hope someone can answer a question regarding the metallicity affecting when a star leaves the main sequence. I would assume a higher metallicity star would have a denser and hotter core and would have a shorter life span, yet apparently the opposite is true. Do larger atoms in the core disrupt the rate of hydrogen fusion?

What is the mechanism by which this difference in metallicity causes a variation in stellar  luminosity and in fusion rates?

  I would also like to know from whence all these dwarf galaxies are cruising by our galaxy such as the LMC and SMC?

Thanks for this really cool review article.

-Larry

Broadly speaking, the metallicity most affects the opacity of the outer layers.  More of the core's light is kept in when the metallicity is higher.  A higher metallicity star can thus generate less light (be less luminous) while still maintaining hydrostatic equilibrium.  So it lasts longer because the rate of fusion can be lower for some given mass.

 

Bear in mind, for the Sun, it takes about a million years for light from the core to get to the photosphere, then only eight minutes to get to us from there.  If the metallicity were higher, it would take more time for that light to get to the photosphere.  That light would "hold up" the outer layers of the Sun longer.

 

Convection and mass loss are much more complicated.  See these lecture notes.  It will give you search terms to push.


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#15 musikerhugh

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Posted 08 February 2022 - 09:53 PM

Yes, great article about what are apparently two of the farthest objects you can see in our Galaxy. So much new information for me - I had no idea about the Sgr dwarf galaxy, so I had to read just to understand the title, inspired by the poetry of the last paragraph. I've been looking at M3 and M53 as a pair of globular clusters near each other in the winter sky, testing the limits of my new 20x80 binoculars on the older, farther one. Now, like all of you, I will be looking for its real partner.

 

Update: last night was clear at about 2 AM after the moon set leaving Bortle 4 Suburban/rural skies, and I was able to spot both M 53 and 5053 easily with APM ED 20 X 80 binoculars. Easily means faint, but obvious. For context, in the same session I was able to discern M81/M82, M65/M66, and M51. On the other hand, I could not make out M101 and had to convince myself I was seeing the spindle of M108. Number of years viewing: two.


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#16 rekokich

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Posted 09 February 2022 - 12:52 PM

Thank you, Hugh.

You might want to try your new binoculars on globular cluster NGC 2419, which is nearly 6 times more distant, but still orbiting the Milky Way. Its integrated magnitude is around 9, and angular size 6 arcmin. It lies at a heliocentric and galactocentric distance around 285,000 ly. See the image and background info here:

https://www.cloudyni...-wanderer-lynx/


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#17 musikerhugh

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Posted 10 February 2022 - 09:17 AM

Thanks, Rudy, for the suggestion and the link to another informative and helpful article. Just proves that visual astronomy is not so much about what your eye sees but how your eye sees - translating a smudge of light into knowledge of the structure and history of the cosmos and a way of questioning it. We'll see if the sky stays clear after moon set (a lot of fog rising from the lake now) and if I'm lucky, will be able to compare what's visible in binoculars vs a 15".


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#18 lwbehney

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Posted 10 February 2022 - 11:44 AM

Rudy, I really enjoyed your article about NGC-2419 in the Lynx constellation. It is fascinating to learn it is composed of two groups of stars of differing metallicity. I am curious as to the calculated age of the stars of the central density of this Globular Cluster. 

The collision model to explain this makes some sense in that it might explain how it came to be in such a distant orbit around the Milky-Way.

Also, it is intriguing to note that astronomers have determined it does not contain dark matter. Do they base this conclusion upon the basis of its lower density?

-Larry



#19 rekokich

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Posted 10 February 2022 - 09:32 PM

Hugh,

 

Astrophotography may be more "scientific", "informative", and distributable, but visual observation is a solitary spiritual experience which always takes my breath away. Please keep us updated on your quest for the Intergalactic Wanderer.



#20 rekokich

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Posted 10 February 2022 - 10:49 PM

Larry,

I was unable to find specific information on the metallicities of the two stellar populations in NGC 2419.

From what I have seen in the literature, estimating globular cluster age is very approximate business, and highly dependent on the method used. Spectroscopic metallicity, photometric (color index) metallicity, and the position of the turnoff point on the HR diagram yield different estimates. Look at table 2 (p. 6) in the following article to see significant departures from correlation between the estimated age and [Fe/H] metallicity.
https://arxiv.org/abs/1001.4289

I am presently writing a post about one-armed spiral galaxies NGC4618 and NGC4625. They are surrounded by (or passing through) large low metallicity molecular clouds of hydrogen and helium. As these clouds gravitationally descend toward the galaxy, they concentrate and cause high rates of star-formation around the galaxy. This "rain" of NEW low metallicity stars might be confused with a very ancient stellar population. A similar process could be involved in the formation of mixed population globular clusters. The possibility is supported by the evidence that lower metallicity stars in NGC2419 are located peripherally.

Your question regarding dark matter content is really a question on comparing the total mass of a globular cluster with the mass of the detectable baryonic matter (including optically-luminous matter and radio-luminous gas). The difference between the two may be due to dark matter and/or black holes. Total mass of a stellar system is spectroscopically estimated by measuring stellar velocity dispersion. The method is applicable to clusters, galaxies, and galaxy clusters. You can find an explanation in section 35 here:
https://www.cloudyni...roperties-r3295



#21 DavidWasch

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Posted 16 February 2022 - 07:55 AM

Just wanted to post a quick thank you for the article. It was a great mix of review (h-r diagram, metalicity) and new information (the binary aspects and origin of the pair).

 

New satilite based data is leading to lots of exciting new information, and the investment in these space missions is well spent.


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#22 Mert

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Posted 18 February 2022 - 06:50 AM

Thank you for sharing another brilliantly written article, most informative.

I will have to read a couple of times through it due to the density and

wealth of information given.

For sure I will give this pair of globs a session worth of image time,

very interesting!


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#23 musikerhugh

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Posted 22 February 2022 - 01:56 AM

So, here's my update on the Intergalactic Wanderer.

Ever since reading Rudy's other article, the idea of a lone globular cluster in orbit nearly 3 galaxy-lengths from the Milky Way's center has haunted my imagination. I looked at a couple of star atlases and then star-hopped from α-Gem with my 20x80 binoculars.  I was pretty sure I found it - and saw it - but I kind of had to convince myself. Then, for the past 2 nights, before the moon came up, I took out my 15" Obsession, armed with my Deep Sky Reisatlas and a Telrad, but somehow couldn't find it. I swept and circled, but there were so many stars in the field that I couldn't find the guide stars. Finally tonight, taking a slightly different tactic, I found it. A very dim patch, but very clear: the globular cluster NGC 2149, floating out in the middle of nowhere, an island of a million stars. Thanks, Rudy.


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#24 Rustler46

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Posted 22 February 2022 - 02:36 PM

So, here's my update on the Intergalactic Wanderer.

Ever since reading Rudy's other article, the idea of a lone globular cluster in orbit nearly 3 galaxy-lengths from the Milky Way's center has haunted my imagination. I looked at a couple of star atlases and then star-hopped from α-Gem with my 20x80 binoculars.  I was pretty sure I found it - and saw it - but I kind of had to convince myself. Then, for the past 2 nights, before the moon came up, I took out my 15" Obsession, armed with my Deep Sky Reisatlas and a Telrad, but somehow couldn't find it. I swept and circled, but there were so many stars in the field that I couldn't find the guide stars. Finally tonight, taking a slightly different tactic, I found it. A very dim patch, but very clear: the globular cluster NGC 2149, floating out in the middle of nowhere, an island of a million stars. Thanks, Rudy.

Do you mean NGC 2149 or NGC 2419? I have observed the latter once with my C-11 and photographed it another time via EAA and a 10-inch reflector. Visually it looked like this at 160X:

  • Remote globular cluster in Lynx; mag. 10, ~5" dia., at end of line with two 4th mag. stars; with close scrutiny can see around 1/2 dozen very faint stars; brighter glow in center

This is a most interesting object considering what it is. I'll need to look at the article by Rudy.

 

Russ



#25 Rick W Morgan

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Posted 22 February 2022 - 04:18 PM

Thanks Rudy, for your observations of M53/NGC5053.  First time I observed them was in April 1982 through a 10" f/8 Cave Newtonian.  With a new 28mm RKE @ 72x, the center was partially resolved, with the outer edges (approx 10' total) sparkling with "blue stragglers."  NGC5053 appeared as a patch of light, unresolved (probably due to lightglow in Winston-Salem).  My friend and I discovered that M53 is the northernmost globular cluster known

 

As far as a challenge, try observing the "Ringtail Galaxy" in Corvus. Known as NGC4038/4039, I observed this in April 1988 thru a 13.1" Dobsonian from New River State Park, NC.  It appeared as a backwards question mark to me; it is actually 2 galaxies which are interacting; the larger one appeared 5' long @ 100x. Very peculiar object.  


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