APOD: Virgo Cluster Galaxies (2015 Aug 04)

[APOD Robot]

Virgo Cluster Galaxies

Explanation: Well over a thousand galaxies are known members of the Virgo Cluster, the closest large cluster of galaxies to our own local group. In fact, the galaxy cluster is difficult to appreciate all at once because it covers such a large area on the sky. This careful wide-field mosaic of telescopic images clearly records the central region of the Virgo Cluster through faint foreground dust clouds lingering above the plane of our own Milky Way galaxy. The cluster's dominant giant elliptical galaxy M87, is just below and to the left of the frame center. To the right of M87 is a string of galaxies known as Markarian's Chain. A closer examination of the image will reveal many Virgo cluster member galaxies as small fuzzy patches. Sliding your cursor over the image will label the larger galaxies using NGC catalog designations. Galaxies are also shown with Messier catalog numbers, including M84, M86, and prominent colorful spirals M88, M90, and M91. On average, Virgo Cluster galaxies are measured to be about 48 million light-years away. The Virgo Cluster distance has been used to give an important determination of the Hubble Constant and the scale of the Universe.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[Ann]

I love Rogelio Bernal Andreo's extremely wide-angle images, and I'm sure I've never seen the Virgo cluster like this.

Rogelio's picture shows us (almost) the entire Virgo Cluster and gives us an idea of the distances between the galaxies and their relative sizes. We can see that no major spiral galaxy is really centrally placed. (Sorry, bystander, NGC 4438 is not a major spiral galaxy.)

Two important and large Virgo spirals are strikingly "anemic", poor in star formation, and large. I like this image of M58: it brings out the galaxy's bright center, its yellow bar, its faint spiral structure and its one bright cluster of young blue stars.

Another fascinating galaxy is M90. There is a great text about it here. And here are a few snippets from that text:

For today’s Messier Monday, let’s dive deep inside the Virgo Cluster and check out one of its most spectacular surviving spirals: Messier 90.

In reality, there are an estimated 2,000 galaxies in the Virgo Cluster, but Messier 90 is one of the brightest and largest of all the spirals, significantly brighter than our neighboring big sister: Andromeda.

However, unlike most interacting galaxies, Messier 90 does not exhibit signs of intense star formation along its arms. In fact, it seems to be incredibly poor in gas for a spiral galaxy, and contains very few star-formation regions along its arms even relative to a quiet galaxy like our own!

Over time, a phenomenon known as ram-pressure stripping has caused the vast majority of interstellar gas and dust to be entirely removed from this galaxy.

Even though it’s conspicuous, very large and bright, it’s much lower in mass than we’d expect for a galaxy of this size, indicating just how much of this galaxy has been stripped away!

Fascinating! Note, by contrast, small blue vigorously star forming spiral M99 at 5 o'clock. I have to wonder if its disturbed shape has anything to do with its falling in towards giant hungry elliptical galaxies M86 and M84.

What a great image!

Ann

[hoohaw]

This is wonderful, but I am disappointed that the images are not higher resolution. If you magnify the image, the names are pixilated, not crisp. Are higher resolution versions of the named AND of the un-labelled images available somewhere? Thanks! (This is great!)

[RBA]

Thanks Ann!

Hoohaw, here you go: http://deepskycolors.com/astro/2015/06/ ... abeled.jpg

Best,
Rogelio

[Coil_Smoke]

Where can I get an intergalactic real estate license ... ?

[Ann]

Thanks Ann!

Hoohaw, here you go: http://deepskycolors.com/astro/2015/06/ ... abeled.jpg

Best,
Rogelio

Thanks! A great picture becomes even greater at full resolution!

Ann

[ta152h0]

" scale of the Universe " ?? is there light that has not reached us yet ?

[Visual_Astronomer]

" scale of the Universe " ?? is there light that has not reached us yet ?

Current theory says the universe is larger than what we can see. The "visible universe" is comprised of things within 13.7 billion light years or so - the time since the big bang. There could certainly be light from stars that will never be visible to us.

Last new moon I was looking at this very region of the sky - I stayed in the central area around "Markarian's chain" and identified 28 galaxies. It is a fabulous region for visual astronomy under dark skies.

[henrystar]

" scale of the Universe " ?? is there light that has not reached us yet ?

There sure is! In fact we only detect light from the most minuscule fraction of the Universe. We only see a tiny, tiny, portion of what we "know" i.e. are sure, is there. Main argument is that the famous 3-degree background radiation is essentially exactly the same temperature even on opposite sides of the sky. But at the rate the universe is observed to be expanding, those regions would never have been in thermal contact, to come to the same identical temperature. Therefore, the Universe, very early (first fraction of a second) expanded exponentially. (And of course it is also possible that the Universe is infinite).

[Chris Peterson]

" scale of the Universe " ?? is there light that has not reached us yet ?

Well, there is certainly light inside the observable universe that hasn't reached us. But light beyond the observable universe will never reach us, since that part of the Universe is moving away from us at greater than the speed of light.

[ta152h0]

my brain just blew up. I will have an ice cold one now

[Boomer12k]

Amazing, and THANKS for the overlay....

:---[===] *

[Boomer12k]

Oh, my.....It's full of GALAXIES...to borrow a phrase...

:---[===] *

[Ann]

" scale of the Universe " ?? is there light that has not reached us yet ?

There sure is! In fact we only detect light from the most minuscule fraction of the Universe. We only see a tiny, tiny, portion of what we "know" i.e. are sure, is there. Main argument is that the famous 3-degree background radiation is essentially exactly the same temperature even on opposite sides of the sky. But at the rate the universe is observed to be expanding, those regions would never have been in thermal contact, to come to the same identical temperature. Therefore, the Universe, very early (first fraction of a second) expanded exponentially. (And of course it is also possible that the Universe is infinite).

Click to view full size image

Although the Big Bang happened about 13.8 billion years ago, the observable universe is much larger. According to Wikipedia, the observable universe has a radius of about 46 billion light-years and a diameter of about 93 billion light-years. That's because things that sent out their light to us about 13.7 billion years ago or so have now moved away from us, so that now they are considerably more than 13.7 billion years away.

The most distant objects of any kind that we can see in principle (which doesn't mean that we can see them with our current technology) are about 46 billion light-years away.

Ann