APOD: Looking Through Abell 68 (2013 Mar 08)

[APOD Robot]

Looking Through Abell 68

Explanation: Want to use a cluster of galaxies as a telescope? It's easier than you might think as distant galaxy clusters naturally act as strong gravitional lenses. In accordance with Einstein's theory of general relativity, the cluster gravitational mass, dominated by dark matter, bends light and creates magnified, distorted images of even more distant background galaxies. This sharp infrared Hubble image illustrates the case for galaxy cluster Abell 68 as a gravitational telescope, explored by amateur astronomer Nick Rose during the ESA-Hubble Hidden Treasures image processing competition. Putting your cursor over the picture will label highlights in the scene. Labels 1 and 2 show two lensed images of the same background galaxy. The distorted galaxy image labeled 2 resembles a vintage space invader! Label 3 marks a cluster member galaxy, not gravitationally lensed, stripped of its own gas as it plows through the denser intergalactic medium. Label 4 includes many background galaxies imaged as elongated streaks and arcs. Abell 68 itself is some 2.1 billion light-years distant toward the constellation Vulpecula. The central region of the cluster covered in the Hubble view spans over 1.2 million light-years.

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[bystander]

http://asterisk.apod.com/viewtopic.php?t=30852

[RET]

> toward the constellation Vulpecula.

should be Pisces, I suppose.

[Ann]

This is a really fun and interesting image. What a galactic zoo!!!

Ann

[Boomer12k]

Oh, I LOVE Galactic Lensing shots!!!! COOOOOOL!!!!

"Label two resembles a vintage space invader"!!! ---- SEE??? IT IS NOT JUST ME WHO SEES THINGS IN IMAGES!!!!!!

The problem I see with using it as a TELESCOPE is that the images are distorted, and so you don't see the object in its true form.

But this is a good example of the different phenomena that GL can produce.

:---[===] *

[FLPhotoCatcher]

The label 3 galaxy looks so unusual! Is there another galaxy closer that looks similar?

[Douglas L. Marin]

THANKS FOR EXPANDING MY HORIZON.

[robert hayner]

Wonderful pic; but I need a little more explanation, please
RH

[stephen63]

Wonderful pic; but I need a little more explanation, please
RH

Link to the proposal: http://archive.stsci.edu/proposal_searc ... t&id=11591

[Boomer12k]

> toward the constellation Vulpecula.

should be Pisces, I suppose.

Why should you suppose that?

http://heritage.stsci.edu/2013/09/fast_facts.html

:---[===] *

[NGC3314]

The label 3 galaxy looks so unusual! Is there another galaxy closer that looks similar?

Not as extreme as this, but there are some other examples of ram-pressure stripping caught in the act in clusters:

C153 in Abell 2125 (more details)

NGC 4388 and NGC 4522 in the Virgo cluster.

(Plus more in the Coma cluster and Abell 1367 without very photogenic images on the Web)

To Boomer12k - gravitational lensing does give some of the advantages of a telescope. Lensed objects are brighter in received flux, so we can make measurements of more distant objects of a particular kind than otherwise possible, and at least in the simple case of distortion into an arc or line, that 1D magnification gives us information on finer-scale structure than we could have otherwise (characteristic sizes of star-forming regions or bulges of high-redshift galaxies, for example). I continue to be amazed than in 1937, a year after Einstein's paper setting out the basics of the phenomenon, Fritz Zwicky published a half-page paper setting out what continue to be the basic scientific rationales for the study of gravitational lensing among galaxies.

[Ann]

The label 3 galaxy looks so unusual! Is there another galaxy closer that looks similar?

I think this is an extreme case of ram pressure stripping. Hubble has previously photographed galaxies with much, much milder cases of ram pressure. Here is one example, NGC 4522. Here's another picture of NGC 4522.

NGC 4522 is "falling" through the Virgo Cluster. Its gas is being "swept back" as it is falling headlong towards the great gravity traps of the central elliptical galaxies in Virgo, and at the same time, it encounters extremely hot gas that has been ejected from the galaxies in the cluster by truly supermassive black holes. It is like running upwind and having your hair blown back.

Another example of a nearby ram pressure galaxy is NGC 1427A. Read about it and see a picture of it here.

What I find so amazing about the ram pressure galaxy in today's APOD is that it really looks as if the gas is "dripping" from it, rather than being "swept back" as the galaxy is *falling towards" a galaxy cluster. It actually looks as if the gas of the galaxy is attracted more strongly by the gravity of the cluster than the galaxy itself, running ahead of it into the "maw" of the cluster!!!!

Ann

[zbvhs]

How far away are the lensed galaxies? Does the color provide a clue? Is it possible that lensed galaxies might be reflections of objects in front of the lensing galaxy?

[Fixxxer]

Does the nearly edge-on galaxy that's just up and left of image center have a pair of jets coming from its core, or is that an artifact of the image?
(It's the galaxy that's on the upper-left edge of label #4's ellipse.)

[Chris Peterson]

How far away are the lensed galaxies? Does the color provide a clue? Is it possible that lensed galaxies might be reflections of objects in front of the lensing galaxy?

Lensed galaxies are typically 10-20 times farther away from us than the lensing galaxy (or galaxy cluster). Of course, the distant galaxies have a high redshift, and their apparent color in an image can often be related to redshift, depending on the filters used (although actual spectroscopic measurements are required to determine the actual redshift).

I can't think of any physical mechanism that could produce a reflection like you suggest. In any case, however, the redshifts of the lensed galaxies (which have usually been measured) demonstrate conclusively that they are much farther away than the relatively close foreground galaxies.

[Peeratz]

Does the nearly edge-on galaxy that's just up and left of image center have a pair of jets coming from its core, or is that an artifact of the image?
(It's the galaxy that's on the upper-left edge of label #4's ellipse.)

I noticed this as well, but on other galaxies as well. Is it just lens flare, as it seems to have the same angle as other definite lens flare in the picture?

[RET]

> toward the constellation Vulpecula.

should be Pisces, I suppose.

Why should you suppose that?

http://heritage.stsci.edu/2013/09/fast_facts.html

http://www.spacetelescope.org/videos/heic1304a/
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=aco+68

[LocalColor]

One could get "lost" in this image for a long time. So much to see!

[bystander]

> toward the constellation Vulpecula.
should be Pisces, I suppose.

Why should you suppose that?
http://heritage.stsci.edu/2013/09/fast_facts.html

http://www.spacetelescope.org/videos/heic1304a/
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=aco+68

Hmm, seems STScI may be in error here. The coordinates RA 03h 36m 59s.4 Dec +09° 08' 30" would indicate Cetus. However, SIMBAD lists the coordinates of Abell 68 as RA 00h 37m 06s.2 Dec +09° 09' 33" which would place it in Pisces. Neither of those are anywhere close to Vulpecula. I'm confused.

[Case]

Hmm, seems STScI may be in error here. The coordinates RA 03h 36m 59s.4 Dec +09° 08' 30" would indicate Cetus.

<nitpick>My map shows the Hubble Heritage coordinates to be in Taurus.</nitpick>
The Simbad and NED coordinates are within the Pisces borders, though.

[ta152h0]

Mr Peterson ( of Cloubait Observatory )writes
" Lensed galaxies are typically 10-20 times farther away from us than the lensing galaxy (or galaxy cluster "

So, if we see a lensing galaxy is about 1.4 billion light years away, is it correct to say the lensed galaxy we see is at, near, beyond the calculated age of the Universe ?

[NGC3314]

> toward the constellation Vulpecula.
should be Pisces, I suppose.

Why should you suppose that?
http://heritage.stsci.edu/2013/09/fast_facts.html

http://www.spacetelescope.org/videos/heic1304a/
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=aco+68

Hmm, seems STScI may be in error here. The coordinates RA 03h 36m 59s.4 Dec +09° 08' 30" would indicate Cetus. However, SIMBAD lists the coordinates of Abell 68 as RA 00h 37m 06s.2 Dec +09° 09' 33" which would place it in Pisces. Neither of those are anywhere close to Vulpecula. I'm confused.

I think we're suffering from George Abell's productovity. He produced a catalog of clusters of galaxies, and one of planetary nebulae. NED specializes in galaxies while SIMBAD specializes in individual stars, so they may default to different lists when simply given an Abell designation.

[Chris Peterson]

Mr Peterson ( of Cloubait Observatory )writes
" Lensed galaxies are typically 10-20 times farther away from us than the lensing galaxy (or galaxy cluster "

So, if we see a lensing galaxy is about 1.4 billion light years away, is it correct to say the lensed galaxy we see is at, near, beyond the calculated age of the Universe ?

These lensed galaxies have redshifts in the range of 2.6 to 5.4, corresponding to light travel times of 9 to 10 billion years. The light from these galaxies was emitted when the Universe was just 1-2 billion years old.

[Astromontufar]

I think that abel galaxi cluster is amazing, what do you guys think about it? it is so far away

[MargaritaMc]

I've been reading about the research relating to this image and I'd be grateful if someone could tell me what z means in the following quotation

Spectroscopic measurements are obtained for 26 lensed images, including a distant galaxy at z = 5.4.

http://m.iopscience.iop.org/0004-637X/6 ... .text.html

Many thanks!
Margarita