APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

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APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by APOD Robot » Tue Nov 09, 2010 5:00 am

Image NGC 4452: An Extremely Thin Galaxy

Explanation: Why is there a line segment on the sky? In one of the more precise alignments known in the universe, what is pictured above is actually a disk galaxy being seen almost perfectly edge on. The image from the Hubble Space Telescope is a spectacular visual reminder of just how thin disk galaxies can be. NGC 4452, a galaxy in the nearby Virgo Cluster of Galaxies, is so thin that it is actually difficult to determine what type of disk galaxy it is. Its lack of a visible dust lane indicates that it is a low-dust lenticular galaxy, although it is still possible that a view from on top would reveal spiral structure. The unusual stellar line segment spans about 35,000 light years from end to end. Near NGC 4452's center is a slight bulge of stars, while hundreds of background galaxies are visible far in the distance. Galaxies that appear this thin are rare mostly because our Earth must reside (nearly) in the extrapolated planes of their thin galactic disks. Galaxies that actually are this thin are relatively common -- for example our own Milky Way Galaxy is thought to be about this thin.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by bystander » Tue Nov 09, 2010 5:33 am

HEIC: NGC 4452: An Extraordinarily Slender Galaxy (POTW: 08 Nov 2010)
http://asterisk.apod.com/vie ... 29&t=21941

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Ann » Tue Nov 09, 2010 7:31 am

I found an SDSS image of NGC 4452, which in my opinion is every bit as revealing as the Hubble picture.
You can see the bright, very straight thin disk. You can see that this thin disk is faintly yellowish, because it is made up of old yellowish stars. Moreover, you can see that the disk is the same color all over, which means that all the stars in this disk are (more or less) the same age. Not only that, but you can see that the relatively large halo surrounding the galaxy is the same yellowish color, although it is obviously not as bright. So the stars in the halo, too, are more or less the same age as the stars in the thin disk. While the disk is extremely straight, the halo turns "up" at the right and "down" at the left.

The nuclear bulge is extremely small and barely noticable. No dust is visble at all.

NGC 4452 is situated in the middle of a "ring" of galaxies consisting of supergiant bright tenth magnitude elliptical galaxy M87, plus eleventh and twelfth magnitude S0 galaxies 4503, 4429 and 4371.

Image

Supergiant elliptical galaxy M 87.

The only real spiral galaxy in this ring is NGC 4388. 4388, however, is disturbed, and is expelling a huge amount of gas:
It could be that NGC 4388 shows what has already happened to all the S0 galaxies in that ring of galaxies with M87 in one "corner". An S0 galaxy is a galaxy with a disk but no spiral arms and generally no dust. S0 galaxies also don't have any star formation. NGC 4388 is the only galaxy in this "ring" that has gas and star formation, but the gas is flowing out of NGC 4388 right now, and it has already left NGC 4452, NGC 4503, NGC 4429 and NGC 4371. These galaxies have all become "quiet", yellow and devoid of gas and dust, but they have all retained their disks. They have not had had their constituent stars scrambled into an elliptical swarm. Clearly they are situated in a cosmic environment that is very hostile to galactic gas reservoirs and star formation, but it is not violent enough to smash up the galaxies and destroy their disks.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Boomer12k » Tue Nov 09, 2010 10:15 am

Looks like a crack in the space-time fabric!

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by nstahl » Tue Nov 09, 2010 11:43 am

Clearly they are situated in a cosmic environment that is very hostile to galactic gas reservoirs and star formation
Does anyone have a clue as to what could cause such an environment?

I had no idea we were so thin!

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by owlice » Tue Nov 09, 2010 12:00 pm

Great APOD, image and text!

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Ann » Tue Nov 09, 2010 1:16 pm

nstahl wrote:
Clearly they are situated in a cosmic environment that is very hostile to galactic gas reservoirs and star formation
Does anyone have a clue as to what could cause such an environment?
I think we have a possible culprit here....

Image

M 87 blows a massive jet (actually, two jets) into the Virgo Cluster. Chances are that such forceful jets will help create the sort of environment that blows gas and dust out of neighbouring galaxies.

Image

This is a radio image of the jets of M 87.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by orin stepanek » Tue Nov 09, 2010 1:38 pm

In the links; this great movie on hubble. 8-)
Click to play embedded YouTube video.
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Alan F » Tue Nov 09, 2010 1:39 pm

I think it is a very misleading photograph and too much is being made of its thin, flat appearance. Other photographs do not show it this thin, and it is not on the list of flat galaxies. Perhaps there is some bias due to the wavelengths used or the processing of the photo.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by neufer » Tue Nov 09, 2010 1:55 pm

APOD Robot wrote:Image NGC 4452: An Extremely Thin Galaxy

NGC 4452's lack of a visible dust lane indicates that it is a low-dust LenTicular galaxy,
although it is still possible that a view from on top would reveal spiral structure.
A view from on top would simply reveal that this is Mr. Len Tickle stretching as he wakes up in the morning.
http://en.wikipedia.org/wiki/List_of_Mr._Men wrote:
Image
<<Mr. Tickle is orange with long arms and a small blue hat. Mr. Tickle's story begins with him in bed and making himself breakfast without getting up because of his "extraordinarily long arms". He then decides that it is a tickling sort of day and so goes around town tickling people - a teacher, a policeman, a greengrocer, a station guard, a doctor, a butcher and a postman. The book ends with a warning that Mr. Tickle could be lurking around your doorway, waiting to tickle you.

Mr. Tickle appears under the titles Monsieur Chatouille (French), Don Cosquillas (Spanish), Mr. Goglais (Welsh), Unser Herr Killekille (German), Meneertje Kietel (Dutch), Ο Κύριος Γαργαλίτσας (Greek), 搔癢先生 (Taiwan), 간지럼씨 (Korean), Fætter Kilderik (Danish), Gubben Killekill (Swedish), מר דגדוג (Hebrew), Mr. Csiki (Hungarian) and Senhor Cócegas (Portuguese).

In the 2008 TV series The Mr. Men Show, Mr. Tickle tickles other Mr. Men and Little Misses (due to the obvious absence of humans in Dillydale). As far as character traits goes, he is still determined to tickle everyone he interacts with, but instead of doing it for mischief he does it to make people happy and will stop when nobody wants him to tickle them, save for when the opportunity knocks with Mr. Grumpy (aka, Chris Peterson :wink: ), who appears to be his favorite target. He also gets his own catchphrase, "Somebody needs a tickle!">>
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by bystander » Tue Nov 09, 2010 1:58 pm

Ann wrote:Clearly they are situated in a cosmic environment that is very hostile to galactic gas reservoirs and star formation
nstahl wrote:Does anyone have a clue as to what could cause such an environment?
Ann wrote:I think we have a possible culprit here....

M 87 blows a massive jet (actually, two jets) into the Virgo Cluster. Chances are that such forceful jets will help create the sort of environment that blows gas and dust out of neighbouring galaxies
The jets of M87 would have very little effect on neighboring galaxies, certainly not enough to devoid them of gas and dust. Intergalactic distances are just too vast.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by owlice » Tue Nov 09, 2010 2:09 pm

The background is amazing -- so many galaxies!!!

I'm thinking these might be image artifacts?
[attachment=0]Screen shot 2010-11-09 at 9.10.36 AM.jpg[/attachment]
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Chris Peterson » Tue Nov 09, 2010 2:36 pm

owlice wrote:I'm thinking these might be image artifacts?
I don't think so. Artifacts on Hubble images are either dust shadows that haven't been flatted out completely, or hot/cold pixels. Rarely, I've seen reflections. But there's nothing bright enough in the field (or near it, I think) to produce reflections. I think those are galaxies.
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by kmatt201 » Tue Nov 09, 2010 2:42 pm

Maybe it's just my eyes, but if I stare at the APOD photo, there appear to be some differences in brightness along the line of this galaxy--slightly brighter at each end and roughly half to two-thirds of the way toward the central bright region from each end. If this is not just my imagination, these could be spiral arm structures viewed end-on, brighter of course because of the greater density of stars.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by owlice » Tue Nov 09, 2010 2:54 pm

Chris, thanks very much!

Lots of pretty galaxies in this image!
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by emc » Tue Nov 09, 2010 3:03 pm

Linked from today’s caption… Wikipedia lenticular galaxy http://en.wikipedia.org/wiki/Lenticular_galaxy IC 1101, the largest known galaxy
IC 1101 is a supergiant lenticular galaxy at the center of the Abell 2029 galaxy cluster. It is 1.07 billion light years away in the constellation of Serpens and is classified as a cD class of galaxy.
Size
The galaxy has a diameter of approximately 5 million light years, which makes it currently (as of 2010) the largest known galaxy in terms of breadth.[2] It is thought to contain up to 100 trillion stars, compared to our own galaxy's estimated 0.25 trillion stars, or Andromeda's 1 trillion. Being more than 50 times the size of the Milky Way and 2000 times as massive, if it was in place of our galaxy, it would swallow up the Large Magellanic Cloud, Small Magellanic Cloud, Andromeda Galaxy, and Triangulum Galaxy. IC 1101 owes its size to many collisions of much smaller galaxies about the size Milky Way and Andromeda galaxies.

Image
Does the lack of dust/interstellar matter in these lenticular galaxies indicate they're dying?
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Saketpofali » Tue Nov 09, 2010 3:44 pm

Do we have picutres in other wavelenghts like infrared, ultraviolet, x-rays? That might reveal a bit more about the disk than just normal picture.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Chris Peterson » Tue Nov 09, 2010 4:16 pm

Ann wrote:I found an SDSS image of NGC 4452, which in my opinion is every bit as revealing as the Hubble picture...
You must be kidding. Move the mouse over the image to compare the HST and SDSS views.
Click to view full size image 1 or image 2
The HST has more than ten times better resolution, shows finer structure in the disc, halo, and bulge, shows a much thinner disc than the SDSS, and has much more accurate color.

I see nothing to recommend the SDSS image over the HST at all.
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Ann » Tue Nov 09, 2010 4:59 pm

Chris wrote:

has much more accurate color
Absolutely not. NGC 4452 is completely dominated by yellow stars. The bright white color in the HST image is plain wrong.

The HST image is great in many ways, but the lousy color balance of it prompted me to find a picture showing the actual yellow color of the galaxy.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Ann » Tue Nov 09, 2010 5:21 pm

bystander wrote:

The jets of M87 would have very little effect on neighboring galaxies, certainly not enough to devoid them of gas and dust. Intergalactic distances are just too vast.
You may certainly be right there. So there is something called ram pressure. If I understand it correctly, it might be a consequence of the generally great speeds of galaxies in a massive cluster like the Virgo cluster. The high speeds of the galaxies are themselves casued by the great total mass of the cluster. And since the space between the galaxies is not empty, and since there is probably a bit more tenuous gas between the galaxies in a massive galaxy cluster like Virgo than there is in, say, the Local Group of galaxies that we belong to, the fast-moving galaxies of the Virgo Cluster experience a strong headwind all the time as they whirl about. This strong wind may be enough to drive the gas and dust out of the galaxies.

One galaxy clearly experiencing the effects of ram pressure is NGC 4402. It is "falling into" the Virgo cluster in the general direction of giant elliptical galaxy M86:
NGC 4402. Note how the gas is sort of "boiling away", and note how the lower part of the galaxy is stripped bare of gas, dust and young stars.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Chris Peterson » Tue Nov 09, 2010 6:10 pm

Ann wrote:Absolutely not. NGC 4452 is completely dominated by yellow stars. The bright white color in the HST image is plain wrong.
Yes. Yellow stars like the Sun. Otherwise described by most people as a warm white. Which is precisely the color seen in the HST image. In the SDSS image, on the other hand, there is a garish orange color that is seen in the galaxy halo as well as many surrounding sources. The color variations seen in the HST image are much more subtle and reveal much more information. The color processing in the HST image is MUCH better, and IMO has produced a much more accurate image.
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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Ann » Tue Nov 09, 2010 6:21 pm

Chris wrote:

Yes. Yellow stars like the Sun.
No, Chris.

The stars that dominate NGC 4452 are not like the Sun. The color index of the Sun is about +0,62. Unfortunately my astronomical software suffers some kind of glitch so that it refuses to tell me the color index of galaxies, but I'll bet you this - the color index of NGC 4452 is not less than +0.80.

NGC 4452 is a yellow galaxy because it is made up of stars that are generally yellower than the Sun.

The Sun, however, is not yellow, unless you want to argue that the color of daylight is yellow.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Zenodotus » Tue Nov 09, 2010 6:35 pm

Has anyone noticed the relatively symmetric layout of the distant galaxies in the background? They is almost like they are following magnetic field lines or defined arcs. They also seem to have a similar progressive change in color as they get closer or farther from NGC 4452. I don't know much about telescopes . Are these attributes caused by optical lensing? or perhaps gravity lensing.
My new theory is that these lines of galaxies and stars are actually all the same galaxy or star. The lines of galaxies are just images of the same galaxy at different points in time. Like we are only seeing the image of the galaxy every few million years like a moving strobe light. Each image is burnt in somehow. Maybe a passing galaxy affects local time and slows time in one part of the universe. Ill work out the details and get back to you :) lol. What do you think? Why are those galaxies oriented in this fashion? I've noticed this in many POD photos.

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by emc » Tue Nov 09, 2010 8:50 pm

Image

Image

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Re: APOD: NGC 4452: An Extremely Thin Galaxy (2010 Nov 09)

Post by Chris Peterson » Tue Nov 09, 2010 11:25 pm

Ann wrote:The stars that dominate NGC 4452 are not like the Sun. The color index of the Sun is about +0,62. Unfortunately my astronomical software suffers some kind of glitch so that it refuses to tell me the color index of galaxies, but I'll bet you this - the color index of NGC 4452 is not less than +0.80.
It is possible to look at this analytically. NGC 4452 has a B-V = 0.89. B-V can be converted to a black body temperature equivalent, and in this case we get 5000 K.

The HST image has a central color of 1.0/0.94/0.90, which corresponds to a temperature of 5400 K and a B-V of 0.8.

The SDSS image has a central color of 1.0/0.81/0.66, which corresponds to a temperature of 4000 K and a B-V of 1.3.

The expected color for a 5000 K object would be 1.0/0.93/0.84, which is seen here (but may not render correctly, depending on your browser and monitor calibration):
c5400k.jpg
There is no doubt that the HST image is photometrically more accurate, better represents both the temperature and B-V index, and IMO the apparent color comes closer to representing the actual nature of the objects that make it up.
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