APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 3642
Joined: Fri Dec 04, 2009 3:27 am

APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by APOD Robot » Sun Jul 28, 2013 4:10 am

Image Hoags Object: A Strange Ring Galaxy

Explanation: Is this one galaxy or two? This question came to light in 1950 when astronomer Art Hoag chanced upon this unusual extragalactic object. On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. Between the two is a gap that appears almost completely dark. How Hoag's Object formed remains unknown, although similar objects have now been identified and collectively labeled as a form of ring galaxy. Genesis hypotheses include a galaxy collision billions of years ago and the gravitational effect of a central bar that has since vanished. The above photo taken by the Hubble Space Telescope in July 2001 revealed unprecedented details of Hoag's Object. More recent observations in radio waves indicate that Hoag's Object has not accreted a smaller galaxy in the past billion years. Hoag's Object spans about 100,000 light years and lies about 600 million light years away toward the constellation of the Snake (Serpens). Coincidentally, visible in the gap (at about one o'clock) is yet another ring galaxy that likely lies far in the distance.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Beyond » Sun Jul 28, 2013 4:18 am

Ring-Ring. I like Ring Galaxies. They look so neat and orderly and so... so... donut like. This one also reminds me of an inner tube, just calmly floating about, in the ocean of space.
To find the Truth, you must go Beyond.

User avatar
geckzilla
Ocular Digitator
Posts: 8973
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by geckzilla » Sun Jul 28, 2013 4:25 am

Every time this object is featured I am bothered by the coincidental ring galaxy in the gap. It's very tempting to say it's some kind of cosmic joke. "Let's make this type of galaxy quite rare and then stick another one of the same type right here so that the Earthlings will have something to ponder."
Just call me "geck" because "zilla" is like a last name.

User avatar
Galaxian
Ensign
Posts: 44
Joined: Sat May 26, 2012 10:23 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Galaxian » Sun Jul 28, 2013 6:42 am

APOD Robot wrote:
<<snipped>>

How Hoag's Object formed remains unknown, although similar objects have now been identified and collectively labeled as a form of ring galaxy. Genesis hypotheses include a galaxy collision billions of years ago and the gravitational effect of a central bar that has since vanished.
It's obvious. The Great and Wise Ghantu blew a smoke-ring then flicked burning ash from his cigar through it. I'd have thought *anyone* could see this.

APOD Robot wrote: <<snipped>>
Coincidentally, visible in the gap (at about one o'clock) is yet another ring galaxy that likely lies far in the distance.
And, to my eyes, which are hot and tired and not working at their best, at about two minutes past two inside the murky ring of stellar fire can be seen another reddish object that just could be a third ring galaxy. Unless it's just one of those ordinary blobby bits where stars are being born?

User avatar
Ann
4725 Å
Posts: 9680
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Ann » Sun Jul 28, 2013 6:47 am

What makes Hoag’s Object so interesting is the brightness of the ring and the clear, wide separation between the yellow elliptical “body” and the blue ring.

Image
NGC 7217. Photo: Adam Block
Ring galaxies are not so unusual, but typically they have central bars that channel gas along them and facilitate the formation of rings. Unbarred ring galaxies are more unusual. NGC 7217 is a prime example. And M94, which is not obviously barred - my software classifies it as unbarred - has an inner and an outer ring, with a separation between the outer ring and the main galaxy.



Image
NGC 1291. Credit: NASA/JPL-Caltech/SSC
NGC 1291 is slightly similar to Hoag’s Object in that there appears to be a very clear separation between the yellow elliptical “body” and the blue ring. But NGC 1291 also has an inner ring and a bar.

Ring galaxies come in various shapes. Personally I think that the Sombrero Galaxy, M104, has a few features in common with a ring galaxy. And the "gap" link of today's APOD takes us to a picture of Saturn's rings. Indeed, there are some similarites between Saturn and a ring galaxy.

Ann
Last edited by Ann on Sun Jul 28, 2013 6:55 am, edited 1 time in total.
Color Commentator

User avatar
Galaxian
Ensign
Posts: 44
Joined: Sat May 26, 2012 10:23 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Galaxian » Sun Jul 28, 2013 6:54 am

geckzilla wrote:Every time this object is featured I am bothered by the coincidental ring galaxy in the gap. It's very tempting to say it's some kind of cosmic joke. "Let's make this type of galaxy quite rare and then stick another one of the same type right here so that the Earthlings will have something to ponder."
Friend, this cosmos is chock full of coincidences, lucky breaks and things that are downright weird. I am in it and that's extremely unprobable. If you really want a coincidence, how about a huge great rock slamming into the Ocean just when it was most needed to help the little furries grow into Hominids? Or Sol just happening to be in a quiet part of the galaxy for long enough for humans to get born? (Ooooh, anthropic principle alert.)
This cosmos is itself unlikely, or maybe it's absolutely certain. Whatever, it's certainly fun and it is decorated with some truly gorgeous special effects. Ring galaxies are among the loveliest.

User avatar
geckzilla
Ocular Digitator
Posts: 8973
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by geckzilla » Sun Jul 28, 2013 6:58 am

Galaxian wrote:Friend, this cosmos is chock full of coincidences, lucky breaks and things that are downright weird. I am in it and that's extremely unprobable. If you really want a coincidence, how about a huge great rock slamming into the Ocean just when it was most needed to help the little furries grow into Hominids? Or Sol just happening to be in a quiet part of the galaxy for long enough for humans to get born? (Ooooh, anthropic principle alert.)
This cosmos is itself unlikely, or maybe it's absolutely certain. Whatever, it's certainly fun and it is decorated with some truly gorgeous special effects. Ring galaxies are among the loveliest.
If the Universe is destined to expand forever until it dies and becomes dark, wouldn't the Universe spend most of its time in that state? I mean, it could be in that state infinitely longer than it is in its living, moving, bright state. Coincidentally, we happen to exist in this tiny slice of time. That's my ultimate coincidental conundrum. (Something isn't right with it.)
Just call me "geck" because "zilla" is like a last name.

User avatar
Ann
4725 Å
Posts: 9680
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Ann » Sun Jul 28, 2013 7:43 am

geckzilla wrote:
If the Universe is destined to expand forever until it dies and becomes dark, wouldn't the Universe spend most of its time in that state? I mean, it could be in that state infinitely longer than it is in its living, moving, bright state. Coincidentally, we happen to exist in this tiny slice of time. That's my ultimate coincidental conundrum. (Something isn't right with it.)
[off topic]
Why isn't it right?
To the best of our understanding, the universe has been forever changing since it was born some 13.82 billion years ago. The Hubble Telescope has shown us that galaxies have been forever changing since they started forming a few hundred million years after the Big Bang. The Earth has been forever changing since it was born some four billion years ago. Consider! The Earth was once a planet full of bacteria, but no other life forms. Then there was the Pre-Cambrian explosion, and suddenly the oceans of the Earth were teeming with trilobites whose fossils are seen everywhere in marble structures. Then we had the long reign of the dinosaurs. Where are they now?

And consider your own life. You will get to live for a hundred years if you are lucky. Consider the eons that existed before you were born, and the eons that will come after you are gone.

Why shouldn't the universe be like a living being in that it has its birth, its childhood, its youth, its prime and its long, long, long decline? What's wrong about that idea?

If the things that are in the universe are forever changing, why should we expect the universe itself to be separate from the things it contains, so that the universe itself can be eternal and unchanging in stark contrast to the sum of its parts? Isn't that a totally weird concept?
[/off topic]

Ann
Color Commentator

Boomer12k
:---[===] *
Posts: 2550
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Boomer12k » Sun Jul 28, 2013 11:46 am

I need to do more research.....


:---[===] *

User avatar
neufer
Vacationer at Tralfamadore
Posts: 16153
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by neufer » Sun Jul 28, 2013 12:19 pm

Click to play embedded YouTube video.
Art Neuendorffer

User avatar
geckzilla
Ocular Digitator
Posts: 8973
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by geckzilla » Sun Jul 28, 2013 3:49 pm

Ann wrote:
geckzilla wrote:
If the Universe is destined to expand forever until it dies and becomes dark, wouldn't the Universe spend most of its time in that state? I mean, it could be in that state infinitely longer than it is in its living, moving, bright state. Coincidentally, we happen to exist in this tiny slice of time. That's my ultimate coincidental conundrum. (Something isn't right with it.)
Why isn't it right?
Too many assumptions. You know what they say about assumptions. I also had two other possible conclusions: Either time also ends if the Universe reaches absolute zero or the Universe does not ever end like that. I should probably avoid philosophy like I avoid talking about politics or the economy.
Just call me "geck" because "zilla" is like a last name.

gmPhil
Ensign
Posts: 34
Joined: Tue Nov 02, 2010 9:15 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by gmPhil » Sun Jul 28, 2013 4:02 pm

It's fasscinating to ponder what the night sky might look like to a being on a planet orbiting a small star somewhere towards the inner edge of the outer ring....

gonzo gonzales

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by gonzo gonzales » Sun Jul 28, 2013 7:04 pm

First, I have no astronomy training - I dropped AST 301 due to a personality conflict with the idiot teaching it.
But, I am considered a very good amateur photographer, so I understand "perspective" and "depth of field".
This leads me to ask myself (and you): how are you so certain that the red star is WITHIN the ring nebulae?
Could it not be that the angle from Hubble is such that the star APPEARS to be within the ring, but in actuality is many light years BEHIND (?) it? This would mean that the star is even larger than you surmise, or that the ring is smaller by X times than you previously measured.

But, kudos to you anyway, I very much enjoy the site and encourage you in your endeavors.

Ramon "gonzo" Gonzales

User avatar
Ann
4725 Å
Posts: 9680
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Ann » Sun Jul 28, 2013 7:49 pm

gonzo gonzales wrote:First, I have no astronomy training - I dropped AST 301 due to a personality conflict with the idiot teaching it.
But, I am considered a very good amateur photographer, so I understand "perspective" and "depth of field".
This leads me to ask myself (and you): how are you so certain that the red star is WITHIN the ring nebulae?
Could it not be that the angle from Hubble is such that the star APPEARS to be within the ring, but in actuality is many light years BEHIND (?) it? This would mean that the star is even larger than you surmise, or that the ring is smaller by X times than you previously measured.

Ramon "gonzo" Gonzales
You are right. There is no visible red star in the ring. There is a very small and very red spot at eight o'clock, but that is clearly no star. I would guess that it is a mistake of some sort.

However, there is one background galaxy at 12.30 and two background galaxies at 2.30. The ones at 2.30 are seen through the ring. The brighter of the two is clearly extended, so it is definitely a galaxy. The fainter one is not so obviously extended, but we can be sure it is a galaxy anyway. How so? It is because it is it is the same reddish-orange color as the object next to it that is obviously a galaxy. All three background galaxies, including the ring galaxy at 12.30, are a lot more orange than the yellow component of Hoag's Object. Yet their intrinsic colors are likely to be just yellow, not orange at all. But precisely because they are background objects they are very far away, and the white and yellow light they emitted hundreds of millions of years ago has been "stretched" by the expansion of the universe to an orange color.

So indeed, we can be sure that the small but extended orange objects are background galaxies that are much more distant than Hoag's Object precisely because they are so orange in color.

Ann
Color Commentator

User avatar
geckzilla
Ocular Digitator
Posts: 8973
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by geckzilla » Sun Jul 28, 2013 7:54 pm

gonzo gonzales wrote:First, I have no astronomy training - I dropped AST 301 due to a personality conflict with the idiot teaching it.
But, I am considered a very good amateur photographer, so I understand "perspective" and "depth of field".
This leads me to ask myself (and you): how are you so certain that the red star is WITHIN the ring nebulae?
Could it not be that the angle from Hubble is such that the star APPEARS to be within the ring, but in actuality is many light years BEHIND (?) it? This would mean that the star is even larger than you surmise, or that the ring is smaller by X times than you previously measured.

But, kudos to you anyway, I very much enjoy the site and encourage you in your endeavors.

Ramon "gonzo" Gonzales
The idiot astronomers have to grapple with questions of distance all the time and have come up with a few ways to make such determinations. However, any idiot also knows there aren't any single stars visible within the galaxy. It's too far away and the resolution is not fine enough. Anything that appears to be a single star is actually either a foreground star from our own galaxy, some distant smudge of a galaxy, or some other large clumping of multiple stars in Hoag's object. Anyway, this idiot is unsure what "star" you are referring to, "gonzo".
Just call me "geck" because "zilla" is like a last name.

User avatar
neufer
Vacationer at Tralfamadore
Posts: 16153
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by neufer » Sun Jul 28, 2013 9:02 pm

http://en.wikipedia.org/wiki/Gonzo_journalism wrote:
Image
<<Gonzo journalism is a style of journalism that is written without claims of objectivity, often including the reporter as part of the story via a first-person narrative. The word "gonzo" is believed to be first used in 1970 to describe an article by Hunter S. Thompson, who later popularized the style. The term has since been applied to other subjective artistic endeavors.

Gonzo journalism involves an approach to accuracy through the reporting of personal experiences and emotions, as compared to traditional journalism, which favors a detached style and relies on facts or quotations that can be verified by third parties. Gonzo journalism disregards the strictly edited product favored by newspaper media and strives for a more personal approach; the personality of a piece is equally as important as the event the piece is on. Use of sarcasm, humor, exaggeration, and profanity is common.

The term "gonzo" was first used in connection with Hunter S. Thompson by The Boston Globe magazine editor Bill Cardoso in 1970. He described Thompson's "The Kentucky Derby Is Decadent and Depraved", which was written for the June 1970 Scanlan's Monthly, as "pure Gonzo journalism." Cardoso claimed that "gonzo" was South Boston Irish slang describing the last man standing after an all-night drinking marathon. He also claimed that it was a corruption of the French Canadian word "gonzeaux", which means "shining path", although this is disputed.>>
Art Neuendorffer

User avatar
Ann
4725 Å
Posts: 9680
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Ann » Sun Jul 28, 2013 9:18 pm

Can't resist going off topic again. But you started the "Ring" song, Art!
Click to play embedded YouTube video.
(If nothing else, this video gives you the chance to wonder at the kind of stage clothes worn by the members of ABBA. Fascinating.)Image

Ann
Color Commentator

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Beyond » Sun Jul 28, 2013 9:52 pm

neufer wrote: Gonzo journalism disregards the strictly edited product favored by newspaper media and strives for a more personal approach; the personality of a piece is equally as important as the event the piece is on. Use of sarcasm, humor, exaggeration, and profanity is common.
This somehow seems somewhat familiar to me, except for the profanity part. It's like I've run across examples of "Gonzo" journalism at various places in the Asterisk* at various times, but just don't really remember where and when, to be able to point any of them out. I seem to remember that a lot of them were of a good sort, but i also seem to remember not thinking of them as being "Gonzo" journalism. "Gonzo journalism" doesn't seem to be a term that "sticks" with me as a description of something. Perhaps it's more of a "City Dwellers" term? :ssmile:
To find the Truth, you must go Beyond.

ta152h0
Schooled
Posts: 1346
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by ta152h0 » Sun Jul 28, 2013 11:05 pm

This is why I stay up late, just to see what misteries the sky controller sends our way
Wolf Kotenberg

User avatar
Chris Peterson
Abominable Snowman
Posts: 14458
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Chris Peterson » Sun Jul 28, 2013 11:30 pm

gmPhil wrote:It's fasscinating to ponder what the night sky might look like to a being on a planet orbiting a small star somewhere towards the inner edge of the outer ring....
I expect it would look very similar to our own night sky.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Chris Peterson
Abominable Snowman
Posts: 14458
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Chris Peterson » Sun Jul 28, 2013 11:43 pm

geckzilla wrote:The idiot astronomers have to grapple with questions of distance all the time and have come up with a few ways to make such determinations. However, any idiot also knows there aren't any single stars visible within the galaxy. It's too far away and the resolution is not fine enough.
I'm not so sure about that. Looking at the image, it appears that quite a few individual stars within the galaxy are resolved. Certainly, both Hubble and ground-based telescopes regularly resolve individual stars inside galaxies. This galaxy is only a little outside the range where Cepheid variables can be used to assess distance. In any case, resolution only determines the distance stars must be apart for them to be isolated from each other. Since this galaxy has very sparse regions (as between the core and ring), even a single bright star has a good chance of being resolved (detected).
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 16153
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by neufer » Mon Jul 29, 2013 1:10 am

Chris Peterson wrote:
gmPhil wrote:
It's fasscinating to ponder what the night sky might look like to a being on a planet orbiting a small star somewhere towards the inner edge of the outer ring....
I expect it would look very similar to our own night sky.
Wouldn't there be a noticeable sparsity of nearby stars?
Art Neuendorffer

cbak80

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by cbak80 » Mon Jul 29, 2013 1:10 am

Do you supose the Sombrero Galaxy would look like this if it were viewed from above or below rather than edge on?

User avatar
Chris Peterson
Abominable Snowman
Posts: 14458
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by Chris Peterson » Mon Jul 29, 2013 1:23 am

neufer wrote:
Chris Peterson wrote:
gmPhil wrote:
It's fasscinating to ponder what the night sky might look like to a being on a planet orbiting a small star somewhere towards the inner edge of the outer ring....
I expect it would look very similar to our own night sky.
Wouldn't there be a noticeable sparsity of nearby stars?
Most of our nearby stars are within a few hundred ly, so I think you'd need to be very, very close to the edge to have much effect on that.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
geckzilla
Ocular Digitator
Posts: 8973
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Hoags Object: A Strange Ring Galaxy (2013 Jul 28)

Post by geckzilla » Mon Jul 29, 2013 2:59 am

Chris Peterson wrote:I'm not so sure about that. Looking at the image, it appears that quite a few individual stars within the galaxy are resolved. Certainly, both Hubble and ground-based telescopes regularly resolve individual stars inside galaxies. This galaxy is only a little outside the range where Cepheid variables can be used to assess distance. In any case, resolution only determines the distance stars must be apart for them to be isolated from each other. Since this galaxy has very sparse regions (as between the core and ring), even a single bright star has a good chance of being resolved (detected).
Quite a few of them? I'm not sure which ones you mean. The central bulge of stars is probably the best place to look since the dust is cleared out but I assumed even the solitary looking ones in that were clusters of stars. When I process Hubble images I always have a hard time distinguishing the single pixel specks from noise, cosmic rays, or actual stars.
Just call me "geck" because "zilla" is like a last name.