APOD: Markarian's Chain of Galaxies (2019 Mar 31)

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APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by APOD Robot » Sun Mar 31, 2019 4:07 am

Image Markarian's Chain of Galaxies

Explanation: Across the heart of the Virgo Cluster of Galaxies lies a striking string of galaxies known as Markarian's Chain. The chain, pictured here, is highlighted on the right with two large but featureless lenticular galaxies, M84 and M86. Prominent to their lower left is a pair of interacting galaxies known as The Eyes. The home Virgo Cluster is the nearest cluster of galaxies, contains over 2000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies surrounding our Milky Way Galaxy. The center of the Virgo Cluster is located about 70 million light years away toward the constellation of Virgo. At least seven galaxies in the chain appear to move coherently, although others appear to be superposed by chance.

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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by Ann » Sun Mar 31, 2019 5:51 am

APOD Robot wrote:

At least seven galaxies in the chain appear to move coherently, although others appear to be superposed by chance.




















Quite interesting. Here you can see two labeled versions of the chain. (Unfortunately they are differently labeled, but Michael A. Stecker is right to call one of the galaxies NGC 4461.)
Harvard.edu wrote:

The structure of the eight-galaxy Markarian chain is investigated. A structural model with the order of distances 1b-3-4-5 is shown to have a higher probability than either of the two models studied by Meurers (1977). Analysis of the distance-velocity relationships of the galaxies using the optical-configuration regression line as the frame of reference for the radial velocities reveals that seven of the galaxies form a rigid chain system with equal angular velocity. Its right side (4406) is moving toward the earth at 1100 km/s, while the chain as a whole moves away from the earth at 700 km/s. The galaxy 4374 is found not to fit into this pattern, although it may follow the chain on its own special trajectory, perhaps a retrograde loop of Stroemgren class c.

Okay. Let's translate. Seven of the galaxies form a rigid chain system. The chain starts on the right side with galaxy NGC 4406. 4406 is the NGC number of giant elliptical galaxy M86. M86 is the huge elongated elliptical that you can see more or less in the middle of Michael A. Stecker's picture.

Apparently the galaxies that "follow M86 to the right", NGC 4438 and 4435, NGC 4461 and 4458, probably, NGC 4473 and NGC 4477, form a rigid chain. Amazing! But M86 moves towards us at 1100 km/s, while the average motion of the chain as a whole moves away from the Earth at 700 km/s. Amazing!

What about the other huge elliptical galaxy in Michael A Stecker's picture, M84? According to the Harvard abstract, M84 (whose NGC number is 4374) doesn't belong to the chain, or at least, it doesn't follow the chain on the same trajectory as the other seven galaxies.

Wowzers! This is fascinating, if you ask me!

Ann
Last edited by Ann on Sun Mar 31, 2019 6:11 am, edited 1 time in total.
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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by De58te » Sun Mar 31, 2019 5:59 am

Fascinating. I take it that at 70 million ly that all the starlike lights in the photo are galaxies even further away than Markarian's Chain. Curious how the Eye below M84 has arms that are entirely blue with young stars whereas the Eye above M84 has a red core with white arms and no blue. Also the strange shaped galaxy near the centre of photo has two blue spiral arms on its side but no blue arms appear in front of its core. And also some of the disk shaped galaxies on the left are completely yellow or white with no blue star forming regions.

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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by Ann » Sun Mar 31, 2019 6:41 am

De58te wrote:
Sun Mar 31, 2019 5:59 am
Fascinating. I take it that at 70 million ly that all the starlike lights in the photo are galaxies even further away than Markarian's Chain. Curious how the Eye below M84 has arms that are entirely blue with young stars whereas the Eye above M84 has a red core with white arms and no blue. Also the strange shaped galaxy near the centre of photo has two blue spiral arms on its side but no blue arms appear in front of its core. And also some of the disk shaped galaxies on the left are completely yellow or white with no blue star forming regions.

Galaxies near the center of large galaxy groups tend to lose more and more of their star forming ability. That is why you typically find mostly elliptical galaxies inside large galaxy clusters.

NGC 4438 and 4435. Photo: ESO/VLT.
NGC 4438. Photo: ESA/Hubble.























NGC 4438 is actually not strikingly blue at all. Its B-V color is +0.85, which means it hasn't got very many hot stars at all, and its U-B color is +0.50, meaning that it is forming few new hot stars.

Take a look at the picture at left. You can see that the arms of NGC 4438 are tenuous and weak and probably made up mostly of A- and F-type stars like Sirius and Procyon. Hints of hotter stars can be seen to the left of the yellow bulge and near the tattered dust lane, and also in the "outstretched arm" at right.

The picture at right is a closeup of the inner part of NGC 4438. Note the white "stars" of a similar brightness scattered across the face of NGC 4438. They may be globular clusters. Note a few bluish clumps of stars near the dust structures at top. They may be young blue clusters. Note the overall bluish color of the top right part of the galaxy, suggesting a presence of many A-type stars and some young clusters. Finally, not the reddish "bubble" near the very center of NGC 4438, indicating an active black hole having little outbursts.

(And by the way, is that a tiny nucleated dwarf satellite galaxy of NGC 4438 that can be seen at top left in the picture at left, and at bottom right in the picture at right? It might be.)

In any case it is quite clear that NGC 4438 is not rich in young stars.

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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by orin stepanek » Sun Mar 31, 2019 1:01 pm

Mmmm! Would make a nice bracelet or necklace! 8-) Miniaturized galaxies of course! :lol2:
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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by Chris Peterson » Sun Mar 31, 2019 2:33 pm

Ann wrote:
Sun Mar 31, 2019 5:51 am
Harvard.edu wrote:
Analysis of the distance-velocity relationships of the galaxies using the optical-configuration regression line as the frame of reference for the radial velocities reveals that seven of the galaxies form a rigid chain system with equal angular velocity.
Okay. Let's translate. Seven of the galaxies form a rigid chain system.
That seems extremely unlikely... even physically impossible. Probably just a terrible choice of words. If these galaxies are moving together, they are certainly orbiting around each other and their common center of mass in some complex way. There is no way that a system like this could ever be described as "rigid". What we almost certainly have is a small galaxy cluster with the individual members swarming around each other, and the cluster as a whole demonstrating a high common velocity with respect to us.
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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by Ann » Sun Mar 31, 2019 5:13 pm

Chris Peterson wrote:
Sun Mar 31, 2019 2:33 pm
Ann wrote:
Sun Mar 31, 2019 5:51 am
Harvard.edu wrote:
Analysis of the distance-velocity relationships of the galaxies using the optical-configuration regression line as the frame of reference for the radial velocities reveals that seven of the galaxies form a rigid chain system with equal angular velocity.
Okay. Let's translate. Seven of the galaxies form a rigid chain system.
That seems extremely unlikely... even physically impossible. Probably just a terrible choice of words. If these galaxies are moving together, they are certainly orbiting around each other and their common center of mass in some complex way. There is no way that a system like this could ever be described as "rigid". What we almost certainly have is a small galaxy cluster with the individual members swarming around each other, and the cluster as a whole demonstrating a high common velocity with respect to us.
Point taken. I was just quoting the source given by APOD Robot. :wink:

I agree that the word "rigid" seems impossible in this context. But it would be interesting, wouldn't it, if these seven galaxies were particularly strongly bound to one another, or if some sort of tidal force propagating through the interstellar medium was affecting these galaxies specifically.

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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by Chris Peterson » Sun Mar 31, 2019 5:19 pm

Ann wrote:
Sun Mar 31, 2019 5:13 pm
Chris Peterson wrote:
Sun Mar 31, 2019 2:33 pm
Ann wrote:
Sun Mar 31, 2019 5:51 am

Okay. Let's translate. Seven of the galaxies form a rigid chain system.
That seems extremely unlikely... even physically impossible. Probably just a terrible choice of words. If these galaxies are moving together, they are certainly orbiting around each other and their common center of mass in some complex way. There is no way that a system like this could ever be described as "rigid". What we almost certainly have is a small galaxy cluster with the individual members swarming around each other, and the cluster as a whole demonstrating a high common velocity with respect to us.
Point taken. I was just quoting the source given by APOD Robot. :wink:
I know... that's why I left the original quote intact.
I agree that the word "rigid" seems impossible in this context. But it would be interesting, wouldn't it, if these seven galaxies were particularly strongly bound to one another, or if some sort of tidal force propagating through the interstellar medium was affecting these galaxies specifically.
Well, I think they are strongly bound to one another. That's what makes them a cluster! The only way they could be moving as a group in a way that seemed "rigid" would be if they weren't strongly bound, which would only be the case if they were very low mass or very far apart.
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Odd (super)man out: M86 (NGC 4406)

Post by neufer » Sun Mar 31, 2019 6:48 pm

http://www.messier.seds.org/more/m086_cxo.html wrote: Chandra X-ray Observatory images of M86
The Virgo Cluster and M86: Cluster's Gain is Galaxy's Loss

:arrow: <<This composite X-ray (blue)/optical (orange) image of M86 shows gas being swept out of the galaxy to form a long tail more than 200,000 light years in length. Located in the Virgo galaxy cluster, this enormous lenticular or elliptical galaxy is moving at about [1340 km/s] through diffuse hot gas that pervades the cluster. The supersonic motion of M86 produces pressure that is stripping gas from the galaxy and forming the spectacular tail.

M86 has been pulled into the Virgo galaxy cluster and accelerated to a high speed by the enormous combined gravity of dark matter, hot gas, and hundreds of galaxies that comprise the cluster. The infall of the galaxy into the cluster is an example of the process by which galaxy groups and galaxy clusters form over the course of billions of years.

The galaxy is no longer an "island universe" with an independent existence. It has been captured and its gas is being swept away to mix with the gas of the cluster, leaving an essentially gas-free galaxy orbiting the center of the cluster along with hundreds of other galaxies.>>
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Re: APOD: Markarian's Chain of Galaxies (2019 Mar 31)

Post by Fred the Cat » Mon Apr 01, 2019 12:03 am

MarkarianChain_Kaminsky_2710 b.jpg
NGC4402 looks like a cosmic pizza. All those hot gasses should have it done in nanoseconds! :wink:
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Re: Odd (super)man out: M86 (NGC 4406)

Post by Ann » Mon Apr 01, 2019 2:57 am

neufer wrote:
Sun Mar 31, 2019 6:48 pm
http://www.messier.seds.org/more/m086_cxo.html wrote: Chandra X-ray Observatory images of M86
The Virgo Cluster and M86: Cluster's Gain is Galaxy's Loss

:arrow: <<This composite X-ray (blue)/optical (orange) image of M86 shows gas being swept out of the galaxy to form a long tail more than 200,000 light years in length. Located in the Virgo galaxy cluster, this enormous lenticular or elliptical galaxy is moving at about [1340 km/s] through diffuse hot gas that pervades the cluster. The supersonic motion of M86 produces pressure that is stripping gas from the galaxy and forming the spectacular tail.

M86 has been pulled into the Virgo galaxy cluster and accelerated to a high speed by the enormous combined gravity of dark matter, hot gas, and hundreds of galaxies that comprise the cluster. The infall of the galaxy into the cluster is an example of the process by which galaxy groups and galaxy clusters form over the course of billions of years.

The galaxy is no longer an "island universe" with an independent existence. It has been captured and its gas is being swept away to mix with the gas of the cluster, leaving an essentially gas-free galaxy orbiting the center of the cluster along with hundreds of other galaxies.>>

Fascinating, Art. I wasn't aware that M86 is leaking so much gas, or that it, in fact, has fallen into the Virgo Cluster. That would explain why M86 and M84, which look so similar (although one is obviously elongated and one is not) appear to follow such different trajectories through the Virgo Cluster. M86 and M84 are apparently quite unrelated.

NGC 4402. Photo: ESA/Hubble.

As Fred pointed out in the post below yours (although he pointed it out obliquely, through a link), NGC 4402, which is seen right above M86 in today's APOD, is also falling into the Virgo Cluster. And because it is a spiral galaxy, it has become obviously distorted by its reckless plunge into the hot intergalactic medium of of this large cluster of galaxies.


In your Chandra picture, Art, it looks as if M86 and NGC 4402 are falling in together, as if they were bound together. Maybe they are, too. Maybe NGC 4402 always used to be a satellite galaxy of M86.


Ann


EDIT: Here is the Chandra page that originally published the X-ray picture of M86. This page contains more information about the picture, such as when it was taken. This page also contains a link to a Chandra picture of NGC 4438 and NGC 4435, The Eyes.
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