APOD: Virgo Cluster Galaxies (2023 May 26)

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APOD: Virgo Cluster Galaxies (2023 May 26)

Post by APOD Robot » Fri May 26, 2023 4:05 am

Image Virgo Cluster Galaxies

Explanation: Galaxies of the Virgo Cluster are scattered across this nearly 4 degree wide telescopic field of view. About 50 million light-years distant, the Virgo Cluster is the closest large galaxy cluster to our own local galaxy group. Prominent here are Virgo's bright elliptical galaxies Messier catalog, M87 at bottom center, and M84 and M86 (top to bottom) near top left. M84 and M86 are recognized as part of Markarian's Chain, a visually striking line-up of galaxies on the left side of this frame. Near the middle of the chain lies an intriguing interacting pair of galaxies, NGC 4438 and NGC 4435, known to some as Markarian's Eyes. Of course giant elliptical galaxy M87 dominates the Virgo cluster. It's the home of a super massive black hole, the first black hole ever imaged by planet Earth's Event Horizon Telescope.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Fri May 26, 2023 9:20 am


The most interesting aspect of today's APOD is the enormous yellow halos around the massive elliptical galaxies, M87 (bottom), M86 (elongated galaxy near top) and M84 (top). These enormous yellow halos add incredible mass to these elliptical galaxy monsters.


Just below M86 is bystander, or the Eyes galaxies, NGC 4435 and NGC 4438. NGC 4438 has some blue stars and some star formation, which is very unusual for galaxies in the center of the Virgo Cluster.

Near center of the APOD is a cute and very elegant little barred spiral galaxy. It appears to be made up of old stars only.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by mostly cloudy » Fri May 26, 2023 5:26 pm

I would have liked to explore more of Abdullah Al-Harbi‘s wonderful photographs, but a Instagram account is required. 🙁

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by AVAO » Fri May 26, 2023 7:28 pm

mostly cloudy wrote: Fri May 26, 2023 5:26 pm I would have liked to explore more of Abdullah Al-Harbi‘s wonderful photographs, but a Instagram account is required. 🙁
Try https://www.astrobin.com/users/Abdullah_alharbi/

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Fri May 26, 2023 7:38 pm

Markarians Chain annotated Joe Renzetti.png
Markarian's Chain. Image credit: Joe Renzetti

In galaxy clusters, the individual galaxies tend to lose their gas and dust and spiral arms and turn into "yellow blobs" or ellipticals. In the Virgo Cluster we find three very big ellipticals, M87, M86 and M84. M87 is the biggest of them, and it is famous for its monstrous black hole!


M86 and M84 form one end of a long "chain" of galaxies, Markarian's Chain. What I find most fascinating about Markarian's Chain is a possible interaction and gas flow between NGC 4438 and M86:

Bridge of gas between M86 and NGC 4438 Tomer Tal and Jeffrey Kenney NOIRLab.png
Bridge of gas between M86 and NGC 4438
Credits: Tomer Tal and Jeffrey Kenney/Yale University and NOAO/AURA/NSF


There are many fascinating things to see in the picture by Tomer Tal and Jeffrey Kenney! First of all, there is an amazing bridge of gas between giant elliptical galaxy M86 and smallish distorted spiral galaxy NGC 4438. Or is that bridge for real? Some astronomers believe that this gaseous feature is merely a foreground cirrus cloud in the Milky Way. Well, maybe so, but isn't it a remarkable coincidence that the bridge appears to begin at NGC 4438, one of the few galaxies in Markarian's Chain that contains dust and gas? And isn't it remarkable that the bridge appears not just to originate at reasonably gas-rich NGC 4438 but also to flow towards the center of gravity in Markarian's Chain, huge elliptical galaxy M86?

There are more things going on near elliptical galaxy M86. Look at the outflow from NGC 4438. That thing is for real. And also look at the strange shape of galaxy NGC 4402, which is losing gas all along its dust lane as it is plunging through the intergalactic medium of the Virgo Cluster:


NGC 4402 and NGC 4388 are two doomed gas-losing soon to be ex-spiral galaxies. NGC 4438 is losing gas from its core. It seems all but certain that the cause of the mass loss from NGC 4388 is the antics of its massive and active black hole. However, galaxy D100 in the Coma Cluster is losing gas from its center because it is falling through the intergalactic medium of the Coma Cluster, and it has already lost all the gas in its disk:


And finally, let's look at IC 3355, a small irregular galaxy that looks intensely pink in the picture by Tomer Tal and Jeffrey Kenney:

IC 3355 NOIRLab.png
IC 3355. Credit: Tomer Tal/Jeffrey Kenney/Yale University and NOAO/AURA/NSF

I can't be sure, but based on its appearance I'd say that IC 3355 could be a small galaxy being captured by the Virgo Cluster and falling through its intergalactic medium. It still retains most of its gas, but the "friction" between the intergalactic medium and its own gas probably triggers a lot of star formation.

The intergalactic medium of large galaxy clusters strips the constituent galaxies of gas. The intergalactic medium of large galaxy clusters is made of lots of scattered old stars, huge amounts of ambient hot gas and a lot of dark matter.


The intergalactic medium of a large galaxy cluster is a dangerous place! Watch out!

Ann
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by AVAO » Fri May 26, 2023 7:46 pm

APOD Robot wrote: Fri May 26, 2023 4:05 am Image Virgo Cluster Galaxies

Near the middle of the chain lies an intriguing interacting pair of galaxies, NGC 4438 and NGC 4435, known to some as Markarian's Eyes.
ThanX Ann - your post was faster 8-)
...so as an addition...

Active Galaxy NGC 4438: "A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth." (Source: ESA)

Core Area with black hole in NGC 4438: It doesn't look like bubbles to me, it's like loops.
...and the gas bridge between NGC 4438 (left) and M86 (right)... (can be seen in a composit Image of H alpha (red / NOAO/AURA/NSF) and X-ray gas (blue/violett / KIPAC).

...in a high active region.
Image
(image collage from different sources and wavelengths)
biggg: https://live.staticflickr.com/65535/521 ... de52_o.jpg

jac berne (flickr)
Last edited by AVAO on Sat May 27, 2023 6:34 am, edited 1 time in total.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by johnnydeep » Fri May 26, 2023 9:06 pm

AVAO wrote: Fri May 26, 2023 7:28 pm
mostly cloudy wrote: Fri May 26, 2023 5:26 pm I would have liked to explore more of Abdullah Al-Harbi‘s wonderful photographs, but a Instagram account is required. 🙁
Try https://www.astrobin.com/users/Abdullah_alharbi/
Wow, the full resolution version is 35 MB!
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by orin stepanek » Sat May 27, 2023 12:42 am

virgoCL1024.jpg
Glad it's not my job to count them! :mrgreen: :lol2:
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Sat May 27, 2023 6:39 am

AVAO wrote: Fri May 26, 2023 7:46 pm
APOD Robot wrote: Fri May 26, 2023 4:05 am Image Virgo Cluster Galaxies

Near the middle of the chain lies an intriguing interacting pair of galaxies, NGC 4438 and NGC 4435, known to some as Markarian's Eyes.
ThanX Ann - your post was faster 8-)
...so as an addition...

Active Galaxy NGC 4438: "A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth." (Source: ESA)

...and the bridge between M86 and NGC 4438
(can be seen in a composit Image the X-ray gas is visible in blue (source: KIPAC))
...image collage from different sources and wavelengths...

...in a high active area...
Image
biggg: https://live.staticflickr.com/65535/521 ... de52_o.jpg
jac berne (flickr)
Thanks AVAO, I always appreciate the pictures you post! :D

Your picture of the bridge between NGC 4438 and M86 shows more than mine, since your picture also includes X-rays.

And I really like your last picture! The deceptively smallish-looking object with red outflows at lower center left is of course giant elliptical galaxy M87 and the great outflows from the monstrous black hole. But I particularly like your inclusion of large but "waning" spiral galaxy M90 at top left in your image. So here is a closeup of M90:

Image[1].jpg
Massive outflows of gas from M90. Credit: MegaCam at CFHT/Coelum.
Canada France Hawaii Telescope wrote:

The colour image of the galaxy NGC 4569 in the Virgo cluster, obtained with MegaCam at the CFHT. The red filaments at the right of the galaxy show the ionised gas removed by ram pressure. This is about 95% of the gas reservoir of the galaxy needed to feed the formation of new stars (image ©2015 CFHT/Coelum).
So M90 has been losing 95% of the gas needed to create new stars!!! :shock: How does that affect the colors of M90?


What about the B-V and U-B indices of M90? The B-V index is 0.720, which is quite normal for a large galaxy that is bound to contain huge numbers of old red stars. But the U-B index, 0.425, is red, and it means that M90 has formed few or no ho massive stars lately.


Let's have a look at a map of the location of Virgo Cluster galaxies. I found the map on the Wikipedia page for M88, which is why there is an arrow pointing at M88. Remember that the center of the Virgo Cluster is at M87, M86 and M84.


Let's have a look at some of the outliers, shall we? M64 is the Black Eye Galaxy! You will have to read the Wikipedia entry yourselves.

Another outlier is M85, a lenticular galaxy without star formation with a suppressed and not at all richly starforming spiral companion, NGC 4394.

Yes, but look at outlier M61, which is truly bursting with star formation!


Has the intergalactic medium robbed M81 of any of its gas? I don't think so! M61 is almost "extremely blue for a large galaxy": Its B-V is 0.510, and its U-B is —0.110.

The only large galaxy that I can think of off hand that is bluer than M61 is M101, the Pinwheel Galaxy!

And finally, I can't help myself. Do look at this brilliant picture by Mark Hanson of M90 and nearby elliptical galaxy M89:


And if I'm not allowed to post this picture, and the picture disappears, then do go to this page to read about the picture and the galaxies!

Ann
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by VictorBorun » Sat May 27, 2023 11:55 am

what puzzle me most:
1) a chain of galaxies may be a disk we see edge-on, but then Markarian's Chain is a disk at the edge of the Virgo cluster. How come?
2) foreground stars belonging to Milky Way galaxy seem to be a big problem for the image on wiki but not so for this APOD:
Click to view full size image 1 or image 2
Virgo Cluster.jpg
Virgo Cluster 2.jpg
...
How come?
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by mostly cloudy » Sat May 27, 2023 5:06 pm

AVAO wrote: Fri May 26, 2023 7:28 pm
mostly cloudy wrote: Fri May 26, 2023 5:26 pm I would have liked to explore more of Abdullah Al-Harbi‘s wonderful photographs, but a Instagram account is required. 🙁
Try https://www.astrobin.com/users/Abdullah_alharbi/
Many thanks! 🙂

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Sat May 27, 2023 5:09 pm

VictorBorun wrote: Sat May 27, 2023 11:55 am what puzzle me most:
1) a chain of galaxies may be a disk we see edge-on, but then Markarian's Chain is a disk at the edge of the Virgo cluster. How come?
2) foreground stars belonging to Milky Way galaxy seem to be a big problem for the image on wiki but not so for this APOD:
Click to view full size image 1 or image 2
Virgo Cluster.jpgVirgo Cluster 2.jpg
...
How come?
As for the question of foreground stars, I'll pass.

But when it comes to the structure of Markarian's Chain, and the chain of galaxies lining up, I personally believe that we are seeing an effect of the cosmic web.

Matter is not distributed equally in the cosmos, but instead it "organised" into filaments and voids:


The way I understand it, the cosmic filaments are quite literally "full of galaxies". Well, not full of galaxies, but galaxies tend to line up along those filaments. In reality, the filaments are elongated structures of dark matter and baryonic ("ordinary") matter in the form of gas. This is where galaxies typically form.

I think, therefore, that the galaxies of Markarian's Chain have formed along a filament of dark matter and gas.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Chris Peterson » Sat May 27, 2023 5:23 pm

Ann wrote: Sat May 27, 2023 5:09 pm But when it comes to the structure of Markarian's Chain, and the chain of galaxies lining up, I personally believe that we are seeing an effect of the cosmic web.

Matter is not distributed equally in the cosmos, but instead it "organised" into filaments and voids:
Filaments link superclusters, not the individual galaxies within galaxy clusters. The galaxies in the Virgo Cluster are gravitationally bound, which means they are in orbit around the cluster center (and in a sense around each other due to n-body perturbations). That means the chain is transient as an apparently linear structure. Like lines of stars that catch our eyes, a coincidence. (And a number of the galaxies in the chain are actually background galaxies that aren't in line with the others at all.)
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Sat May 27, 2023 7:12 pm

Chris Peterson wrote: Sat May 27, 2023 5:23 pm
Ann wrote: Sat May 27, 2023 5:09 pm But when it comes to the structure of Markarian's Chain, and the chain of galaxies lining up, I personally believe that we are seeing an effect of the cosmic web.

Matter is not distributed equally in the cosmos, but instead it "organised" into filaments and voids:
Filaments link superclusters, not the individual galaxies within galaxy clusters. The galaxies in the Virgo Cluster are gravitationally bound, which means they are in orbit around the cluster center (and in a sense around each other due to n-body perturbations). That means the chain is transient as an apparently linear structure. Like lines of stars that catch our eyes, a coincidence. (And a number of the galaxies in the chain are actually background galaxies that aren't in line with the others at all.)
I certainly see your point, Chris. I guess that galaxies in galaxy clusters orbit the center of mass of the cluster in a way that is at least slightly similar to how stars in rich star cluster orbit the center of the cluster:

Click to play embedded YouTube video.
Stars orbiting inside a rich star cluster.

For all of that... Some galaxy arrangements sure are suggestive.


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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by AVAO » Sun May 28, 2023 8:42 pm

Chris Peterson wrote: Sat May 27, 2023 5:23 pm
Ann wrote: Sat May 27, 2023 5:09 pm But when it comes to the structure of Markarian's Chain, and the chain of galaxies lining up, I personally believe that we are seeing an effect of the cosmic web.

Matter is not distributed equally in the cosmos, but instead it "organised" into filaments and voids:
Filaments link superclusters, not the individual galaxies within galaxy clusters. The galaxies in the Virgo Cluster are gravitationally bound, which means they are in orbit around the cluster center (and in a sense around each other due to n-body perturbations). That means the chain is transient as an apparently linear structure. Like lines of stars that catch our eyes, a coincidence. (And a number of the galaxies in the chain are actually background galaxies that aren't in line with the others at all.)
I have a different opinion. Neither chains of galaxies nor chains of stars are random, because they contradict the laws of statistical random distribution in thousands of versions.

Stars form in strands of filaments and often persist as chains of stars once the gas and dust have dissipated.

Image
Original data source: https://photojournal.jpl.nasa.gov/jpeg/PIA20357.jpg
IC 417 jac berne (flickr)
Last edited by AVAO on Mon May 29, 2023 12:10 pm, edited 1 time in total.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Chris Peterson » Sun May 28, 2023 8:53 pm

AVAO wrote: Sun May 28, 2023 8:42 pm
Chris Peterson wrote: Sat May 27, 2023 5:23 pm
Ann wrote: Sat May 27, 2023 5:09 pm But when it comes to the structure of Markarian's Chain, and the chain of galaxies lining up, I personally believe that we are seeing an effect of the cosmic web.

Matter is not distributed equally in the cosmos, but instead it "organised" into filaments and voids:
Filaments link superclusters, not the individual galaxies within galaxy clusters. The galaxies in the Virgo Cluster are gravitationally bound, which means they are in orbit around the cluster center (and in a sense around each other due to n-body perturbations). That means the chain is transient as an apparently linear structure. Like lines of stars that catch our eyes, a coincidence. (And a number of the galaxies in the chain are actually background galaxies that aren't in line with the others at all.)
Neither chains of galaxies nor chains of stars are random, because they contradict the laws of statistical random distribution in thousands of versions.

Stars form in strands of filaments and often persist as chains of stars once the gas and dust have dissipated.

Image
Original data source: https://photojournal.jpl.nasa.gov/jpeg/PIA20357.jpg
IC 417 jac berne (flickr)
I think nearly all chains of stars are random, particularly as they almost always lie at different distances (that is, they are not linear structures at all). Of course, there may be very recently formed stars that are still related to each other, but that is rare compared with most of what we see. The "chains" I'm talking about here are the groups of a half dozen or so stars that often show up in astronomical images and our eyes detect as linear. Chains of galaxies that happen to be linear may or may not be random. But if they are inside a cluster, they are almost certainly coincidental alignments, because there is no mechanism to maintain them in a linear orientation.
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by AVAO » Sun May 28, 2023 9:19 pm

Chris Peterson wrote: Sun May 28, 2023 8:53 pm
AVAO wrote: Sun May 28, 2023 8:42 pm
Chris Peterson wrote: Sat May 27, 2023 5:23 pm

Filaments link superclusters, not the individual galaxies within galaxy clusters. The galaxies in the Virgo Cluster are gravitationally bound, which means they are in orbit around the cluster center (and in a sense around each other due to n-body perturbations). That means the chain is transient as an apparently linear structure. Like lines of stars that catch our eyes, a coincidence. (And a number of the galaxies in the chain are actually background galaxies that aren't in line with the others at all.)
Neither chains of galaxies nor chains of stars are random, because they contradict the laws of statistical random distribution in thousands of versions.

Stars form in strands of filaments and often persist as chains of stars once the gas and dust have dissipated.

Image
Original data source: https://photojournal.jpl.nasa.gov/jpeg/PIA20357.jpg
IC 417 jac berne (flickr)
I think nearly all chains of stars are random, particularly as they almost always lie at different distances (that is, they are not linear structures at all). Of course, there may be very recently formed stars that are still related to each other, but that is rare compared with most of what we see. The "chains" I'm talking about here are the groups of a half dozen or so stars that often show up in astronomical images and our eyes detect as linear. Chains of galaxies that happen to be linear may or may not be random. But if they are inside a cluster, they are almost certainly coincidental alignments, because there is no mechanism to maintain them in a linear orientation.
Ok, for linear chains (stars along a STRAIGHT line), I agree.

The chains I mean are mostly curved and twisted, just like filaments. Combining different wavelengths often results in "closed" chains with similar distances between the stars. If certain members of stars in a star chain are missing in visible light, they are often found at other wavelengths such as IR or UV.
Last edited by AVAO on Mon May 29, 2023 3:49 am, edited 1 time in total.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Mon May 29, 2023 3:45 am

AVAO wrote: Sun May 28, 2023 9:19 pm
Chris Peterson wrote: Sun May 28, 2023 8:53 pm
AVAO wrote: Sun May 28, 2023 8:42 pm

Neither chains of galaxies nor chains of stars are random, because they contradict the laws of statistical random distribution in thousands of versions.

Stars form in strands of filaments and often persist as chains of stars once the gas and dust have dissipated.

Image
Original data source: https://photojournal.jpl.nasa.gov/jpeg/PIA20357.jpg
IC 417 jac berne (flickr)
I think nearly all chains of stars are random, particularly as they almost always lie at different distances (that is, they are not linear structures at all). Of course, there may be very recently formed stars that are still related to each other, but that is rare compared with most of what we see. The "chains" I'm talking about here are the groups of a half dozen or so stars that often show up in astronomical images and our eyes detect as linear. Chains of galaxies that happen to be linear may or may not be random. But if they are inside a cluster, they are almost certainly coincidental alignments, because there is no mechanism to maintain them in a linear orientation.
Ok, for linear chains I agree.

The chains I mean are mostly curved and twisted, just like filaments. Combining different wavelengths often results in closed chains with similar distances between stars, which reach their maximum brightness at different wavelengths.
As always, AVAO, I love your pictures. The portrayal of stars forming in a long string is fantastic. Please tell me though, what site of star formation is this? In other words, where are we in this picture?

I agree with you that stars do form in long dust lanes.

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by VictorBorun » Mon May 29, 2023 4:58 am

AVAO wrote: Sun May 28, 2023 8:42 pm
Chris Peterson wrote: Sat May 27, 2023 5:23 pm
Ann wrote: Sat May 27, 2023 5:09 pm But when it comes to the structure of Markarian's Chain, and the chain of galaxies lining up, I personally believe that we are seeing an effect of the cosmic web.

Matter is not distributed equally in the cosmos, but instead it "organised" into filaments and voids:
Filaments link superclusters, not the individual galaxies within galaxy clusters. The galaxies in the Virgo Cluster are gravitationally bound, which means they are in orbit around the cluster center (and in a sense around each other due to n-body perturbations). That means the chain is transient as an apparently linear structure. Like lines of stars that catch our eyes, a coincidence. (And a number of the galaxies in the chain are actually background galaxies that aren't in line with the others at all.)
I have a different opinion. Neither chains of galaxies nor chains of stars are random, because they contradict the laws of statistical random distribution in thousands of versions.

Stars form in strands of filaments and often persist as chains of stars once the gas and dust have dissipated.

Image
Original data source: https://photojournal.jpl.nasa.gov/jpeg/PIA20357.jpg
IC 417 jac berne (flickr)
Stellar chains in Milky Way seen from Solar system are mostly statistic outliers: Big Dipper, Corona Borealis, you name it
Image

However I agree with you on formation of a chain of lights (stars or galaxies, in all scales) is due to gravitational formation of a filament. True stellar filaments are contaminated by background and foreground stars of Mily Way though

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Chris Peterson » Mon May 29, 2023 5:19 am

VictorBorun wrote: Mon May 29, 2023 4:58 am However I agree with you on formation of a chain of lights (stars or galaxies, in all scales) is due to gravitational formation of a filament. True stellar filaments are contaminated by background and foreground stars of Mily Way though
Filaments are associated with dark matter. Stars do not line up along them. When we see structures formed from associated stars, they are short-lived dynamical phenomena resulting from the dynamics of star formation regions. Nor do filaments determine the orientation or movement of galaxies within clusters, because those are dominated by the gravity of the galaxies themselves as well as local dark matter halos. Filaments are structures that are seen at and above the scale of superclusters. Scale matters.
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by VictorBorun » Mon May 29, 2023 8:27 am

Chris Peterson wrote: Mon May 29, 2023 5:19 am
VictorBorun wrote: Mon May 29, 2023 4:58 am However I agree with you on formation of a chain of lights (stars or galaxies, in all scales) is due to gravitational formation of a filament. True stellar filaments are contaminated by background and foreground stars of Mily Way though
Filaments are associated with dark matter. Stars do not line up along them. When we see structures formed from associated stars, they are short-lived dynamical phenomena resulting from the dynamics of star formation regions. Nor do filaments determine the orientation or movement of galaxies within clusters, because those are dominated by the gravity of the galaxies themselves as well as local dark matter halos. Filaments are structures that are seen at and above the scale of superclusters. Scale matters.
Scale just follows both space and time: star formation filaments are short-lived; within a 100 million years your typical open stellar cluster is already hard to trace.
That alone would not stop us from seeing some young stellar chains here and there; what does stop us is the star field being contaminated with false chains of star at different distances and of different luminosity.
The same will be true for large scale foam of filaments and voids when we are able to see well all the galaxies of high red shift: many objects at different distances will be noise drowning the filaments

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Ann » Mon May 29, 2023 12:17 pm

VictorBorun wrote: Mon May 29, 2023 4:58 am

Stellar chains in Milky Way seen from Solar system are mostly statistic outliers: Big Dipper, Corona Borealis, you name it


Image

However I agree with you on formation of a chain of lights (stars or galaxies, in all scales) is due to gravitational formation of a filament. True stellar filaments are contaminated by background and foreground stars of Mily Way though
Big Dipper minus end stars.png

Five of the seven bright stars of the Big Dipper actually belong together. Only the end stars, blue Alkaid and orange Dubhe, are unrelated (and background) party crashers.

Ann
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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by AVAO » Mon May 29, 2023 12:29 pm

Ann wrote: Mon May 29, 2023 3:45 am As always, AVAO, I love your pictures. The portrayal of stars forming in a long string is fantastic. Please tell me though, what site of star formation is this? In other words, where are we in this picture?

Ann
ThanX Ann

...I think the situation in IR at IC 417 is very similar to the Orion Nebula...

HERSCHEL WISE/SST biggg: https://live.staticflickr.com/65535/529 ... c2c1_o.jpg
WISE/SST jac berne (flickr)
bigg:https://www.spitzer.caltech.edu/system/ ... 1603797871
Credit: NASA/JPL-Caltech/T. Megeath (University of Toledo, Ohio)

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Chris Peterson » Mon May 29, 2023 1:52 pm

Ann wrote: Mon May 29, 2023 12:17 pm Five of the seven bright stars of the Big Dipper actually belong together. Only the end stars, blue Alkaid and orange Dubhe, are unrelated (and background) party crashers.
But they are still separate stars, not gravitationally bound together. They are physically near each other, and like most physically close stars in a galaxy are orbiting inside the galaxy at approximately the same speed. The pattern they create, from any viewpoint, is coincidental and transient.
Chris

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Re: APOD: Virgo Cluster Galaxies (2023 May 26)

Post by Chris Peterson » Mon May 29, 2023 1:53 pm

VictorBorun wrote: Mon May 29, 2023 8:27 am
Chris Peterson wrote: Mon May 29, 2023 5:19 am
VictorBorun wrote: Mon May 29, 2023 4:58 am However I agree with you on formation of a chain of lights (stars or galaxies, in all scales) is due to gravitational formation of a filament. True stellar filaments are contaminated by background and foreground stars of Mily Way though
Filaments are associated with dark matter. Stars do not line up along them. When we see structures formed from associated stars, they are short-lived dynamical phenomena resulting from the dynamics of star formation regions. Nor do filaments determine the orientation or movement of galaxies within clusters, because those are dominated by the gravity of the galaxies themselves as well as local dark matter halos. Filaments are structures that are seen at and above the scale of superclusters. Scale matters.
Scale just follows both space and time: star formation filaments are short-lived; within a 100 million years your typical open stellar cluster is already hard to trace.
That alone would not stop us from seeing some young stellar chains here and there; what does stop us is the star field being contaminated with false chains of star at different distances and of different luminosity.
The same will be true for large scale foam of filaments and voids when we are able to see well all the galaxies of high red shift: many objects at different distances will be noise drowning the filaments
My point is that they aren't "filaments" unless there's something binding them together. There is in the case of cosmological structure. There isn't in the case of stars or galaxies inside a cluster.
Chris

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