APOD: Galaxies Away (2018 May 25)

Comments and questions about the APOD on the main view screen.
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APOD: Galaxies Away (2018 May 25)

Post by APOD Robot » Fri May 25, 2018 4:08 am

Image Galaxies Away

Explanation: This stunning group of galaxies is far, far away, about 450 million light-years from planet Earth and cataloged as galaxy cluster Abell S0740. Dominated by the cluster's large central elliptical galaxy (ESO 325-G004), this reprocessed Hubble Space Telescope view takes in a remarkable assortment of galaxy shapes and sizes with only a few spiky foreground stars scattered through the field. The giant elliptical galaxy (right of center) spans over 100,000 light years and contains about 100 billion stars, comparable in size to our own spiral Milky Way galaxy. The Hubble data can reveal a wealth of detail in even these distant galaxies, including arms and dust lanes, star clusters, ring structures, and gravitational lensing arcs.

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S_S

Re: APOD: Galaxies Away (2018 May 25)

Post by S_S » Fri May 25, 2018 5:32 am

I'm wondering, what's the big object seen in yellow color and dumbbell shape in southwest direction from center ? Is that a merging of 2 elliptical galaxies by chance ? Or something totally different ? Thanks for all answers/help in advance.

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Ann
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Re: APOD: Galaxies Away (2018 May 25)

Post by Ann » Fri May 25, 2018 8:36 am

S_S wrote:
Fri May 25, 2018 5:32 am
I'm wondering, what's the big object seen in yellow color and dumbbell shape in southwest direction from center ? Is that a merging of 2 elliptical galaxies by chance ? Or something totally different ? Thanks for all answers/help in advance.
Polar ring galaxy NGC 2685. Photo: Greg Allegretti.
In my opinion, that is probably a lenticular galaxy with a disintegrating polar ring.

In the picture at left, you can see polar ring galaxy NGC 2685. But the yellow dumbbell shaped galaxy in today's APOD seems to be entirely lacking in star formation, unlike NGC 2685. Also the dusty ring structures in NGC 2685 are sharply delineated, while in the dumbbell galaxy in the APOD, they seem to be evaporating.

NGC 2685 is probably a merger product, where the torn-apart remnant of a small spiral or an irregular galaxy has wrapped itself around the main galaxy's yellow bar.

It is possible that the yellow dumbbell in the APOD is also a merger product. But if so, the merger took place long ago, and the faint "belt" around the galaxy's "middle" is the only visible remnant of it.

Ann
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heehaw

Re: APOD: Galaxies Away (2018 May 25)

Post by heehaw » Fri May 25, 2018 9:37 am

Why, all those diverse, sweet, galaxies gathered together .... I'll bet they are all singing! https://www.youtube.com/watch?v=4vu_vSX5kY4

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Re: APOD: Galaxies Away (2018 May 25)

Post by HellCat » Fri May 25, 2018 6:51 pm

Help. I'm lost in all this incredible variety that I can't find the lens.

Any suggestions?

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Re: APOD: Galaxies Away (2018 May 25)

Post by MarkBour » Fri May 25, 2018 8:02 pm

HellCat wrote:
Fri May 25, 2018 6:51 pm
Help. I'm lost in all this incredible variety that I can't find the lens.

Any suggestions?
According to some articles online, it is the central large elliptical galaxy, ESO 325-G004, that is "strongly lensing" (e.g. https://www.sciencedaily.com/releases/2 ... 093405.htm). Can I see any arcs of light it is producing in this APOD? Sorry, like you, I do not.
Mark Goldfain

Nifty

Re: APOD: Galaxies Away (2018 May 25)

Post by Nifty » Fri May 25, 2018 10:33 pm

There's another 'dumbbell' shaped object (pair of objects?) to be seen in the hi-res image directly above the giant elliptical, left of the two spiky stars. Looks interesting. Speaking of spiky stars, are any of those bright spiky objects quasars?

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Re: APOD: Galaxies Away (2018 May 25)

Post by Chris Peterson » Fri May 25, 2018 10:44 pm

Nifty wrote:
Fri May 25, 2018 10:33 pm
Speaking of spiky stars, are any of those bright spiky objects quasars?
Bright and spiky almost always means a nearby star (inside the Milky Way) that happens to lie in the field of view.
Chris

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Sa Ji Tario

Re: APOD: Galaxies Away (2018 May 25)

Post by Sa Ji Tario » Sat May 26, 2018 1:18 am

For Nifti, they seem to be two superimposed galaxies and if they magnify the elliptical galaxy (two clicks) and move it with short up-down or right-left movements, you can see gray circles that may be due to gravitational lens

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Re: APOD: Galaxies Away (2018 May 25)

Post by Cousin Ricky » Sat May 26, 2018 2:08 am

Is this image mirror reversed?

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Re: APOD: Galaxies Away (2018 May 25)

Post by Boomer12k » Sat May 26, 2018 2:56 am

I find it interesting that so far away...there are galaxies that look very much like the ones closer to us... upper right there is a M104 type edge on... and the awesome "S" shape in upper left, like an SBb, Kinda,...Great shot of variety...

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Ann
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Re: APOD: Galaxies Away (2018 May 25)

Post by Ann » Sat May 26, 2018 3:16 am

Nifty wrote:
Fri May 25, 2018 10:33 pm
There's another 'dumbbell' shaped object (pair of objects?) to be seen in the hi-res image directly above the giant elliptical, left of the two spiky stars. Looks interesting. Speaking of spiky stars, are any of those bright spiky objects quasars?
They look like a pair of stars to me. They could be a pair of quite distant Milky Way stars, located thousands of light-years away. Or they could be more nearby, but very faint. Wouldn't it be interesting if they were a pair of white dwarfs?

Double quasar known as QSO 0957+561, or Twin Quasar.
ESA/Hubble & NASA - http://www.spacetelescope.org/images/potw1403a/




















As for quasars, like Chris said, quasars are unusual, while stars are a dime a dozen. Probability itself says that spiky objects are nearby stars.

In the pictures above, however, you can see a pair of quasars. However, they are really just one quasar, being lensed by a foreground massive elliptical galaxy. The two images of the same quasar are labeled A and B, while the lensing galaxy is labeled C.
Wikipedia wrote:
In this new Hubble image two objects are clearly visible, shining brightly. When they were first discovered in 1979, they were thought to be separate objects — however, astronomers soon realised that these twins are a little too identical! They are close together, lie at the same distance from us, and have surprisingly similar properties. The reason they are so similar is not some bizarre coincidence; they are in fact the same object. These cosmic doppelgangers make up a double quasar known as QSO 0957+561, also known as the "Twin Quasar", which lies just under 9 billion light-years from Earth.

Quasars are the intensely powerful centres of distant galaxies. So, why are we seeing this quasar twice? Some 4 billion light-years from Earth — and directly in our line of sight — is the huge galaxy YGKOW G1. This galaxy was the first ever observed gravitational lens, an object with a mass so great that it can bend the light from objects lying behind it.
As a Color Commentator and lover of all blue things, I note, of course, that the quasars look blue. The way I understand it, most quasars look bluish when seen from the Earth. That is because quasars emit absolutely huge amounts of ultraviolet and far-ultraviolet light, which is then redshifted into the shortwave part of the visible spectrum on its (many) billion light-year journey to us. Only the most distant quasars (or the most dust-choked ones) look non-blue when seen from the Earth.

Ann
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Ann
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Re: APOD: Galaxies Away (2018 May 25)

Post by Ann » Sat May 26, 2018 3:23 am

MarkBour wrote:
Fri May 25, 2018 8:02 pm
HellCat wrote:
Fri May 25, 2018 6:51 pm
Help. I'm lost in all this incredible variety that I can't find the lens.

Any suggestions?
According to some articles online, it is the central large elliptical galaxy, ESO 325-G004, that is "strongly lensing" (e.g. https://www.sciencedaily.com/releases/2 ... 093405.htm). Can I see any arcs of light it is producing in this APOD? Sorry, like you, I do not.

Lensed arcs and globular clusters in ESO 325-G004.
Source: https://www.spacetelescope.org/images/opo0708b/

Here they are.

Ann
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