Explanation: Near the heart of the Virgo Galaxy Cluster the string of galaxies known as Markarian's Chain stretches across this deep telescopic field of view. Anchored in the frame at bottom center by prominent lenticular galaxies, M84 (bottom) and M86, you can follow the chain up and to the right. Near center you'll spot the pair of interacting galaxies NGC 4438 and NGC 4435, known to some as Markarian's Eyes. Its center an estimated 50 million light-years distant, the Virgo Cluster itself is the nearest galaxy cluster. With up to about 2,000 member galaxies, it has a noticeable gravitational influence on our own Local Group of Galaxies. Within the Virgo Cluster at least seven galaxies in Markarian's Chain appear to move coherently, although others may appear to be part of the chain by chance.
Galaxy number 1 is NGC 4402. This hapless galaxy is falling headlong through the Virgo Cluster, which is full of hot thin gas. It is like plunging through a terrible upwind, and all your loose possessions may fly away from you in the wind.
As for NGC 4402, the upwind causes much of its gas and dust to be swept away from it in the opposite direction to its plunge through the Virgo Cluster. The phenomenon is called ram pressure. Poor NGC 4402 is going to lose much or all of its starforming material and end up as a "red and dead" disk galaxy, also called a lenticular galaxy.
Galaxy number 2 is giant elliptical galaxy M86. This galaxy is very elongated.
Galaxies number 3 are the "Eyes", NGC 4435 and NGC 4438. NGC 4438 is surrounded by some twisted shreds of spiral arms, which are still bluish. The spiral arms have have been heavily distorted and robbed of much of their gas through the interactions of NGC 4438 with its (too) close companion, smallish elliptical galaxy NGC 4435.
A fascinating aspect of this trio of galaxies - M86, plus NGC 4438 and NGC 4435 - is that there just possibly may be some interaction between them. A very deep image by Mark Hanson shows a reddish bridge between the massive elliptical galaxy and the "Eyes" (and a reddish halo around M86, which is probably a processing effect). The bridge could be a physical feature linking the galaxies, but it could also be some foreground "cirrus clouds" in the Milky Way.
Galaxy number 4 is NGC 4477 (with its small companion NGC 4479). In the APOD, NGC 4477 looks like a quite interesting ring galaxy, doesn't it? But up close it is quite bland, even though you can see hints of the ring feature that is so striking in the APOD. NGC 4477 certainly used to be a (tightly wound) spiral galaxy, and there are hints, but only hints, of spiral arms in it still.
Note that both NGC 4477 and its small companion galaxy are barred galaxies, which is to say that they have an elongated straight feature running through their centers. The bars are bright and prominent in them. But the bar of NGC 4477 is short, while the bar in NGC 4479 is long.
Both NGC 4477 and NGC 4479 are "red and dead". They are uniformly yellow and totally devoid of dark dust lanes, emission nebulas and bright clusters of stars. This is a common fate of galaxies in large clusters, because the cluster environment depresses star formation. Gravitational jostling robs galaxies of much of their gas, and enormous jets from the dominant galaxy's black hole - in the case of the Virgo Cluster, the jet from M87 - heat up the gas in the central parts of the cluster in such a way that it becomes hard or impossible for the gas in nearby galaxies to cool down enough to gather in clumps which can then contract and turn into new stars.
Ann
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 22, 2021 9:28 am
by JohnD
Thank you, Ann, especially for your discussion on NGC 4477. In the APOD pic, it immediately made me think of Hoag's Object, which has figured as an Apod half a dozen times! Could 4477 be a stage in the development of similar galaxies - there seems to be another visible through Hoag's!
John
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 22, 2021 12:53 pm
by orin stepanek
Really does look like a pair of eyes!
Wow! Galaxies galore!
So many galaxies; yet so far apart!
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 22, 2021 2:00 pm
by neufer
Click to play embedded YouTube video.
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 22, 2021 5:59 pm
by Ann
JohnD wrote: ↑Sat May 22, 2021 9:28 am
Thank you, Ann, especially for your discussion on NGC 4477. In the APOD pic, it immediately made me think of Hoag's Object, which has figured as an Apod half a dozen times! Could 4477 be a stage in the development of similar galaxies - there seems to be another visible through Hoag's!
John
There are indeed other ring galaxies than Hoag's Object, although I still think that Hoag's Object is unique. I'm going to post a whole host of images of ring galaxies, so bear with me.
Of the four galaxies I have posted here, Hoag's Object is unique, because the perfectly round yellow core appears to lack any connection whatsoever with the surrounding, almost perfectly circular blue ring. In the other three galaxies, the yellow core does seem to be connected to the outer ring. Galaxy AM 0644-741 has an elongated yellow structure running through its core, and is therefore a barred galaxy. Also its ring appears to have been knocked to one side. The Cartwheel galaxy has what appears to be two inner rings, a bright outer ring and long "spokes" connecting the the yellow center with the outer ring. NGC 1512 looks like a fairly normal nearby "bar and ring" galaxy, although NGC 1512 is special because it has two rings, and inner and an outer ring, and a very long bar that is connected to the outer ring.
The Vela ring galaxy is clearly interacting with another galaxy, and its outer ring has a non-circular shape. It has one and maybe two inner rings too, and what looks like a very faint elongated yellow bar running from upper left to lower right. Arp 147 is an extreme example of interacting galaxies, where the galaxy on the left appears to have passed right through the galaxy on the right, making this galaxy form a blue ring of intense star formation. Mayall's Object looks much like a snapshot of one galaxy passing right through another.
NGC 4477 is not like that. It is a very yellow disk galaxy with a short bar. The disk shows remnants of a ring structure and maybe outer spiral arms, too.
NGC 4477 is just a highly evolved, yellow galaxy whose structures have been weakened by the gravitational jostling of the massive Virgo Cluster. Maybe when NGC 4477 was young, it once was a spiral galaxy. Maybe, just maybe, it looked a bit like NGC 2389 does today.
Orin, that's a great image and wonderfully annotated! I have just copied the small version of your image, so I urge everyone to go to Orin's post and look at the full size image!
Ann
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 22, 2021 7:19 pm
by Fred the Cat
MarkariansChainAnvik1024 (2).jpg (21.22 KiB) Viewed 5147 times
What is that odd shaped galaxy middle near the left margin?
Orin, that's a great image and wonderfully annotated! I have just copied the small version of your image, so I urge everyone to go to Orin's post and look at the full size image!
Ann
Ann: it is in the APOD write up! I'll see if I* can find it!
It is in this
the "Virgo Cluster" itself is the nearest
part of the write up! I can read it when I put it on my computer Full Screen!
It looks like NGC 4440. It is a classic barred grand design galaxy, a majestic barred two-armed galaxy, which in the case of NGC 4440 has completely run out of starforming material and turned tired, red and dead.
An example of a barred two-armed starforming galaxy is NGC 1365.
It looks like NGC 4440. It is a classic barred grand design galaxy, a majestic barred two-armed galaxy, which in the case of NGC 4440 has completely run out of starforming material and turned tired, red and dead.
An example of a barred two-armed starforming galaxy is NGC 1365.
Ann
I just spent quite a while trying to identify it myself, and I was able to even without referring back to your post from 10/10/2020, in response to my asking about the very same galaxy! See http://asterisk.apod.com/viewtopic.php?t=41093#p307085
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sun May 23, 2021 1:52 am
by Fred the Cat
Yes. Thanks all for satisfying my curiosity. I was looking in Stellarium but couldn't quite pin it down.
Thank you for your seminar, Ann! I am that tiny bit wiser!
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Mon May 24, 2021 1:45 pm
by Ginge
Thank you so much for elaborating and sharing your insight, Ann! I was stoked to see Mark Hanson's image with the 30hr Ha added. I'd been searching the web to see what the deepest images were showing when planning the capture, but Hanson's version eluded me. I think I'll try to add Ha next season to see if I can find some of the same. Also I wasn't expecting to find ha-structures as large as this between galaxies, very intriguing indeed. I was going for the IFN between the galaxies, but failed at that as the chain at the time of exposure was seen through a pesky haze that came with the -25C temperatures this winter. I opted in stead for a more traditional rendition of these objects.
The really cool challenge though was that I found I needed to compress the dynamics of each galaxy individually, or each of the most prominent ones. What was working for one was destroying the appearance of another, working with each one separately gave me an appreciation of the spectacular diversity in Markarian's chain although you need to look for it in a large FOV as this.
The danger when doing this, I suppose, is that one can over-process, accentuating certain features in a way that tricks the viewer into thinking NGC4477 is a a ring galaxy like Hoag's object rather than a disk galaxy with a short bar. Very interesting indeed.
Thanks again, very enlightening!
Best regards,
Ginge Anvik
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Fri May 28, 2021 11:53 am
by VictorBorun
orin stepanek wrote: ↑Sat May 22, 2021 12:53 pm
NGC4438_NGC4435_crawford_rc720.jpg
Really does look like a pair of eyes!
I wonder how can a rammer like NGC 4402 (to the left of the center of this picture) show the headwind in the general direction to M86 (above and to the left of the center of this picture) and M87 (much too far above and to the right to fit in this picture). Are these elliptical giants far away from the center of Virgo Cluster's gravitation? Or is NGC 4402 desperately escaping the gravity well?
I wonder how can a rammer like NGC 4402 (to the left of the center of this picture) show the headwind in the general direction to M86 (above and to the left of the center of this picture) and M87 (much too far above and to the right to fit in this picture). Are these elliptical giants far away from the center of Virgo Cluster's gravitation? Or is NGC 4402 desperately escaping the gravity well?
I don't think that the windblown shape of NGC 4402 tells us much about the general "wind" blowing in the Virgo Cluster. Rather, I think the windblown shape of NGC 4402 shows us the wind that NGC 4402 "feels" when it falls through the Virgo Cluster (possibly in the direction of giant elliptical galaxy M86).
Look at the picture of a person falling from a cliff. The person's ponytail stands "upright". That's not because there is a general "upwind" near the cliff - well, there might be one, but that is not the main reason for the "direction" of the ponytail - but rather, the person's interesting hairstyle is due to the fact that the ponytail "feels" the upwind that is created as the person is falling down.
What are these in your picture? Why so many of them?
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 29, 2021 4:22 am
by VictorBorun
orin stepanek wrote: ↑Sat May 29, 2021 1:09 am
If we could will out the Milky Way's stars and see Markaryan's Chain plus M87, we would recognize a picture:
I think the windblown shape of NGC 4402 shows us the wind that NGC 4402 "feels" when it falls through the Virgo Cluster (possibly in the direction of giant elliptical galaxy M86).
Ann
I am confused as how to tease the direction of the ramming from the picture.
The blue arrows show how NGC 4402 is falling through the Virgo Cluster, apparently in the direction of M86.
The yellow arrows show how much of the "loose fluff" of NGC 4402 is being swept back and also lost as NGC 4402 is hurtling through the gaseous intergalactic medium of the Virgo Cluster.
Ann
Re: APOD: Markarian's Chain (2021 May 22)
Posted: Sat May 29, 2021 11:02 am
by VictorBorun
Now I can see.
The stellar population (as well as the dark halo and any central black hole) rams on and looks like a large bluish lens seen edge-on.
Some of the gas, mostly atomic hydrogen fraction, is being stripped away and forms a trailing cylindric column;
it contains some dust lanes and the dust makes the trailing column visible where backlighted by the stellar population.
So what we get to see is that a trailing half part of the lens's thickness is overlayed with dust lanes
which are more prominent against the mid-plane of the lens and get hazy where the lens's backlighting is less dense and close.
A few dust lanes seem to stretch upwind but they in fact are just peripheral ones that happen to be backlighted.
The blue arrows show how NGC 4402 is falling through the Virgo Cluster, apparently in the direction of M86.
The yellow arrows show how much of the "loose fluff" of NGC 4402 is being swept back and also lost as NGC 4402 is hurtling through the gaseous intergalactic medium of the Virgo Cluster.
Ann
offtopic. While in the Beatles Paul McCartney gave away some songs under the nick of Ramon and after the Beatles went Supernova he and Linda issued a disk Ram with an NGC 4402's song going like this:
Ram on, give your heart to somebody
Soon, right away, right away
though astrophysics was yet unaware of the ramming
The blue arrows show how NGC 4402 is falling through the Virgo Cluster, apparently in the direction of M86.
The yellow arrows show how much of the "loose fluff" of NGC 4402 is being swept back and also lost as NGC 4402 is hurtling through the gaseous intergalactic medium of the Virgo Cluster.
Ann
offtopic. While in the Beatles Paul McCartney gave away some songs under the nick of Ramon and after the Beatles went Supernova he and Linda issued a disk Ram with an NGC 4402's song going like this:
Ram on, give your heart to somebody
Soon, right away, right away
though astrophysics was yet unaware of the ramming
That Paul!
I once saw an interview with him (when he had grown almost as old as he is today), and he was asked how he could have created so much great music. He answered, modestly, "Well, I'm a genius!"
Well, who'd'a thunk he would prove to be an astrophysicist prophet, too?