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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 affect of a central bar that has since vanished. The above photo taken by the Hubble Space Telescope in July 2001 reveals unprecedented details of Hoag's Object and may yield a better understanding. 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.

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What a Great picture!! What are the chances of ever getting another Ring picture that you can look through to see another Ring Galaxy??

It's HAL, but with a yellow eye. Kind of like Gandalf the Grey becoming Gandalf the White.

The monoliths elevated him to an infinite level of consciousness. In fact, the monoliths have sent clones of him all over the universe -- they keep an eye on things, as usual.

"near the center lies a ball of much redder stars"
I´m not an astronomist just an amateur, but this i never understood: in the middle of a galaxy should be a dark hole. But on each picture of a galaxy you can see a lightning ball. This should be a complex of red stars? I can´t see that .. and what is 100% sure in this case: this "ball of much redder stars" is NOT "near the center" but IN the center! Who would disagree?

Firstly you can´t see the black hole at those distances but they must be there as they are the only force which holds the galaxy together

With the ring itself I am wondering if light can cause a bending of other light?
Would this be but an optical illusion caused by light bending light?

Waves coming from two directions which meet send a wave off in a different direction altogether. Could this be happening to light?
I know that a radio transmitting on one frequency nearby interferes with radio transmissions on other frequencies quite noticeably.

Re Hoag's Object: A Strange Ring Galaxy (2010 Aug 22)

A great image. The far distant ring galaxy seems to display a bar - is that likely? Also, at about 2 o'clock, within the ring itself, and perhaps seen through it, appears another ring-like object with a central mass. Might this be another ring galaxy?
Is it possible that Hoag's Object has a bar that we are viewing end on?
Keith Saunders

tytower@yahoo.com wrote:Firstly you can´t see the black hole at those distances but they must be there as they are the only force which holds the galaxy together

Um, no. Black holes has the same kind of gravity as everything else has; there's nothing magical about them. A million-solar-mass black hole attracts matter far from it neither more nor less than a globular cluster comprising a million individual sun-sized stars.

With the ring itself I am wondering if light can cause a bending of other light?

Insofar as light has energy and energy is the same as mass, yes. But nowhere in the current universe is there light so intense that it bends spacetime more than the real matter in the neighborhood does. Some transient supernova or GRB events possibly excepted.

Waves coming from two directions which meet send a wave off in a different direction altogether.

Only if the underlying wave equation is nonlinear. The one that governs light is either exactly linear or so close to linear as not to matter. It is extremely well studied, and no experiments have ever shown signs of nonlinearity.

I know that a radio transmitting on one frequency nearby interferes with radio transmissions on other frequencies quite noticeably.

Yes; that is how telescopes work! The images we see are interference patterns across the surface of the detector device. But it takes quite explicit engineering to make this happen for visible light. More precisely, you only get interference if you something that blocks the light from entering certain regions of space, and the edges of that something must be sharp and well-defined on a scale comparable to the wavelength of the light. This is a not unusual occurrence with radio waves, because they are long enough to be compared with buildings and land forms (as well as with your antenna). For visible light it generally only happens in the case of deliberate construction. Natural astronomical phenomena have such large scales that interference effects for visible light are utterly negligible.

Strange object in fact. It makes me think at a apparently crazy hypothesis but, fools aren't mad

I imagine that some very advenced civilisations have perform the ability to transform their "isle univers" to protect themselves from a very active central black hole. And the fact that another galaxy in the same pict also looks like a ring galaxy makes this crazy supposition maybe not so crazy. In fact, these galaxy types is not so current and the fact to find two ones in the same part of the univers (from our point of view of course) is strange by the way. I think that its prudent and wise to think that some civilisations may be technologicaly far more advenced than us.

chrissionair wrote:"near the center lies a ball of much redder stars"
I´m not an astronomist just an amateur, but this i never understood: in the middle of a galaxy should be a dark hole. But on each picture of a galaxy you can see a lightning ball. This should be a complex of red stars? I can´t see that .. and what is 100% sure in this case: this "ball of much redder stars" is NOT "near the center" but IN the center! Who would disagree?

Most galaxies are brightest in the middle. Almost all massive galaxies are brightest in the middle, and if they aren't it is generally because they are distorted to the point that the center of them has been displaced.

Almost all massive galaxies (and perhaps all of them) have a black hole in their centers. But this black hole doesn't look anything like an actual black, as in black, hole, as in hole. Instead, the centers of these galaxies are bright, for two reasons. One, because the stellar density is much higher near the center than further out, so that the light from stars just gets more concentrated near the center (becase there are more stars there). Two, because the black hole may be surrounded by a blindingly bright accretion disk. This happens when gas is orbiting the black hole and funneled down into the hole. Friction in the accretion disk heats the gas (and dust) to very high temperatures and makes them glow very bright.



This is an image of the center of the Milky Way. The bright white object in the middle is a dense star cluster surrounding the black hole at the center of our galaxy. However, at present nothing is falling down into the central black hole of our galaxy, and the black hole is quiet. Even so, our own galaxy is brightest at the center.

What about the "red" stars at the center of galaxies? Simple. With the exception of some rare so called carbon stars and numerous ultra-faint "brown" dwarfs, stars just aren't red. "Red" stars are yellow. So the stars at the center of Hoag's object are typical "red", that is yellow, stars primarily of spectral classes K and M. If you want to know what such "red" stars look like, go out one night and locate the Big Dipper in the northern part of the sky. Follow the arc of the "handle" of the Big Dipper until you come to a bright star. That is Arcturus, a typical "red"giant of spectral class K.



What about the ring galaxy that you can see thorugh the hole of Hoag's Object? Surely that galaxy consists of truly red stars, since it looks really red? No, the red-looking center of that small galaxy is actually made up of stars of the same yellow color as the yellow stars of Hoag's object. The difference is that the smaller-looking galaxy is much further away. And because space is expanding, the yellow light that these stars emitted (corresponding to a wavelength of about 580 nm) has been "stretched" by the expanding space to longer wavelengths, corresponding, perhaps, to an average wavelength of, say, 610 or 620 nm.

Ann

What causes the ring?
I have a theory....
When the Central Massive Black Hole is "feeding", it sends out a large amount of radiation and gases jet away from the center. This "solar wind" or in this case, "Galactic Wind" destroys the central spiral bar when those stars die out. OR they never formed because the wind had already blown most of the gas and dust to the edges of the galaxy. Thus the CMBH holds the older stars near the center. And having blown the dust to the edges that is where star formation then occurs. Thus the ring appearance.
This appears to be happening to M104, The Sombrero Galaxy. You see very little dust in the central areas of the galaxy. But most is at the edges. Like the dust is being blown there. This is probably what will happen to M104. Take a look. Notice the central area. Notice the outer area of dust. Notice the lack of Spiral Arm Structure. Notice how THIN this galaxy is. When the rest is blown to the edges, star formation will form only there...

http://imgsrc.hubblesite.org/hu/db/imag ... ge_web.jpg

The other thing to notice is these are CIRCULAR GALAXIES. Not necessarily SPIRALS!!!

Just my little theory...

Ann wrote: ... This is an image of the center of the Milky Way. The bright white object in the middle is a dense star cluster surrounding the black hole at the center of our galaxy. However, at present nothing is falling down into the central black hole of our galaxy, and the black hole is quiet. Even so, our own galaxy is brightest at the center.

Ann introduced to me the concept that a black hole can, at times, be "quiet". Obviously, the time span that we have observed the existence of black holes is so limited but what could make them start up to begin with, turn off and on -or- perhaps even cycle through active and less-active states? Are there any theories about this?

It looks like an elliptical galaxy inside of a spiral.

Boomer12k wrote:
What causes the ring? I have a theory....

When the Central Massive Black Hole is "feeding", it sends out a large amount of radiation and gases jet away from the center. This "solar wind" or in this case, "Galactic Wind" destroys the central spiral bar when those stars die out. OR they never formed because the wind had already blown most of the gas and dust to the edges of the galaxy. Thus the CMBH holds the older stars near the center. And having blown the dust to the edges that is where star formation then occurs. Thus the ring appearance.

This appears to be happening to M104, The Sombrero Galaxy. You see very little dust in the central areas of the galaxy. But most is at the edges. Like the dust is being blown there. This is probably what will happen to M104. Take a look. Notice the central area. Notice the outer area of dust. Notice the lack of Spiral Arm Structure. Notice how THIN this galaxy is. When the rest is blown to the edges, star formation will form only there...

Click to view full size image

The other thing to notice is these are CIRCULAR GALAXIES. Not necessarily SPIRALS!!!

Just my little theory...

I'm not sure about your "little theory" , "Boomer12k" , but I do agree
that the Hoag's Object is just a distant example of M104 seen face on.

Understanding nearby M104 will lead to understanding Hoag's Object.

http://antwrp.gsfc.nasa.gov/apod/ap080308.html
http://antwrp.gsfc.nasa.gov/apod/ap070505.html
http://antwrp.gsfc.nasa.gov/apod/ap070121.html
http://antwrp.gsfc.nasa.gov/apod/ap060115.html
http://antwrp.gsfc.nasa.gov/apod/ap060929.html
http://antwrp.gsfc.nasa.gov/apod/ap970208.html

http://en.wikipedia.org/wiki/Sombrero_Galaxy wrote:
<<The Sombrero Galaxy (also known as M 104 or NGC 4594 ) is an unbarred spiral galaxy in the constellation Virgo. It has a bright nucleus, an unusually large central bulge, and a prominent dust lane in its inclined disk. The dark dust lane and the bulge give this galaxy the appearance of a sombrero. The galaxy has an apparent magnitude of +9.0, making it easily visible with amateur telescopes. The large bulge, the central supermassive black hole, and the dust lane all attract the attention of professional astronomers.

___ Dust ring

As noted above, this galaxy's most striking feature is the dust lane that crosses in front of the bulge of the galaxy. This dust lane is actually a symmetric ring that encloses the bulge of the galaxy. Most of the cold atomic hydrogen gas and the dust lies within this ring. The ring might also contain most of the Sombrero Galaxy's cold molecular gas, although this is an inference based on observations with low resolution and weak detections. Additional observations are needed to confirm that the Sombrero galaxy's molecular gas is constrained to the ring. Based on infrared spectroscopy, the dust ring is the primary site of star formation within this galaxy.

___ Nucleus

The nucleus of the Sombrero galaxy is classified as a low ionization nuclear emission region (LINER). These are nuclear regions where ionized gas is present, but the ions are only weakly ionized (i.e. the atoms are missing relatively few electrons). The source of energy for ionizing the gas in LINERs has been debated extensively. Some LINER nuclei may be powered by hot, young stars found in star formation regions, whereas other LINER nuclei may be powered by active galactic nuclei (highly energetic regions that contain supermassive black holes). Infrared spectroscopy observations have demonstrated that the nucleus of the Sombrero Galaxy is probably devoid of any significant star formation activity. However, a supermassive black hole has been identified in the nucleus (as discussed in the subsection below), so this active galactic nucleus is probably the energy source that weakly ionizes the gas in the Sombrero Galaxy.

___ Central supermassive black hole

In the 1990s, a research group led by John Kormendy demonstrated that a supermassive black hole is present within the Sombrero Galaxy. Using spectroscopy data from both the CFHT and the Hubble Space Telescope, the group showed that the speed of rotation of the stars within the center of the galaxy could not be maintained unless a mass 1 billion times the mass of the Sun, or 10⁹M☉, is present in the center. This is among the most massive black holes measured in any nearby galaxies.>>

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The Foundation

Elaine: I've got a really good idea for a hat.
It combines the spirit of old Mexico with a little big city panache.
I like to call it the Urban Sombrero.

J. Peterman: Yes, yes. Go on, go on, go on.

Elaine: Well, see, it's... businessmen taking siestas. You know, it's the, uh, the Urban Sombrero.

[Peterman walks out, groaning.]

Elaine: Mr. Peterman? ...................................
Jerry Seinfeld: All right, so what? You put out the catalog. How bad could it be?

[Elaine takes out the Urban Sombrero and puts it on.]

Jerry: What is that?

Elaine: It's the Urban Sombrero. I put it on the cover.

Jerry: Well, nobody sees the... cover.
------------------------------------

biddie67 wrote:

Ann wrote: ... This is an image of the center of the Milky Way. The bright white object in the middle is a dense star cluster surrounding the black hole at the center of our galaxy. However, at present nothing is falling down into the central black hole of our galaxy, and the black hole is quiet. Even so, our own galaxy is brightest at the center.

Ann introduced to me the concept that a black hole can, at times, be "quiet". Obviously, the time span that we have observed the existence of black holes is so limited but what could make them start up to begin with, turn off and on -or- perhaps even cycle through active and less-active states? Are there any theories about this?

The way I understand it, Biddie, it's fairly normal state of affairs for central black hole to be quiet. The thing to bear in mind is that a central black hole with stars orbiting around it can be regarded as an extremely enlarged version of our own solar system. At the center of the solar system is the Sun, which contains, if I remember correctly, as much as 99% of all mass in our solar system. The planets with their moons orbit around the Sun, as well as asteroids, comets, minor planets and assorted space debris.

Now, how often does anything actually fall into the Sun? It happens, particularly for comets, which tend to follow highly elliptical orbits around the Sun. On the other hand, most comets are really low-mass, and the Sun isn't very much affected by swallowing one of those. But what would happen if a planet, say Mercury, actually fell into the Sun? My guess is that the Sun would act up quite noticably.

But the thing to remember is that things don't normally fall into the Sun. It is much the same things with central black holes. Things don't normally fall into them, and then the black holes are quiet.

In some cases, however, a steady stream of gas is funneled into the central black hole of a galaxy, and you get an active black hole and quite possibly a bright accretion disk.

This is a picture of the central part of giant elliptical galaxy M 87. Even though M 87 is an elliptical galaxy with no star formation and no gas in its outer parts, there is nevertheless gas swirling around the trillion Solar mass central black hole and being funneled into it:
In response to the gas being funneled into it, the black hole of M87 blows a powerful jet:
In fact, M 87 is like a volcano, all of it powered by the gas being funneled into the central black hole:
This image was recently posted here by bystander in another folder, by the way.

Two other large elliptical galaxies blow incredible jets, NGC 5128 and NGC 1275. Both these galaxies are ellipticals that are undergoing tremendous collisions with spiral galaxies. Gas from the spirals are being funneled into the supermassive central black holes of the ellipticals.
NGC 5128.
NGC 1275.

Why is the central black hole of the Milky Way quiet? Well, "our" hole is lightweight compared with the typical black hole of a giant elliptical. Also, our galaxy isn't undergoing a merger or a collision. There is no guarantee that gas won't suddenly start being funneled into the central black hole of the Milky Way, and it will almost certainly happen when the Milky Way passes close to the Andromeda galasy a couple of billion years from now.

Ann

Sirs/Madam,

This is my first discusion on this forum and it has been prompted by the Hubble's Picture of the Hoags Object.
Although it has been labeled a ring galaxy, it appears as if it is something else. The galaxy has a concentration of stars toward the observer, that appear to diffuse and spread out at the outskirts and away from the observer. This gives the appearance of a convex cylindrical object with the narrowing toward the observer.
Th bright yellow object does not appear to be at immediate center. It is as if the cylindrical object was blown away fro the yellow object.
Because all galaxy has a black hole consuming nearby stars, this could be a black hole that has consume matter and gained mass allowing it to glow and repel the surrounding unconsumed star and matter, resulting in the open convex cylindrical shape of the galaxy remnant.

The fact that another galaxy can be seen through the clear inner area of the Hoags, in this case, indicate that that area is nearly empty space. Also, there is scant remnant of dust material. this seems to indicate that all the dust is converted to stars, an indication of the age of the structure, or the action of powerful forces converting all the dust material to stars.

wagedeth-the-taileth wrote:
It's HAL, but with a yellow eye.

If Hoags Object is a dormant M87 and "HAL suddenly wakes up"
then his "Evil-Eye" is pointed straight at us.

http://en.wikipedia.org/wiki/Li%27l_Abner wrote:
<<[Li'l Abner's] Evil-Eye Fleegle: Fleegle had a unique and terrifying skill—the evil eye. An ordinary "whammy", as he called it, could stop a charging bull in its tracks. A "double whammy" could fell a skyscraper, leaving Fleegle exhausted. His dreaded "triple whammy" could melt a battleship—but would practically kill Fleegle in the process. The zoot suit-clad Fleegle was a native of Brooklyn, and his burlesque New York accent was unmistakable—especially when addressing his "goil", the zaftig Shoiley. Fleegle was so popular, licensed plastic replicas of Fleegle's face were produced in the 1950s, to be worn like lapel pins. Battery-operated, the wearer could pull a string and produce a flashing light bulb "whammy". Fleegle was reportedly based on a real-life character, a Runyonesque local boxing trainer and hanger-on named Benjamin "Evil Eye" Finkle. Finkle and his famous "hex" were a ringside fixture in New York boxing circles during the 1930s and '40s. Fleegle was vividly portrayed by character actor Al Nesor in the aforementioned stage play and film.>>

Neufer wrote:

I'm not sure about your "little theory" , "Boomer12k" , but I do agree
that the Hoag's Object is just a distant example of M104 seen face on.

Interesting, neufer. And you do argue your case well. Let me point out a possible difference between Hoag's object and M104. Hoag's object does appear to have real star formation, but M 104, by contrast, seems devoid of massive young stars.

Take a look of this GALEX ultraviolet atlas of nearby galaxies.

http://www.galex.caltech.edu/media/glx2 ... img01.html

The most ultraviolet galaxies are on the left, and the least ultraviolet ones are on the right. You can find M87, with its ultraviolet jet, in the seventh row from the top as number eight from the left. M104 is in the same row, but it is only number twelve from the left. There is not much star formation going on there.

Image deleted; go to link above. Warning: VERY large file. ~ Owlice

By the way, note ring galaxy NGC 5701. It is the eleventh row from the top (number four from the bottom) and it is number five from the left. It looks quite a lot like Hoag's object, and it definitely appears to have more star formation than M104.

Here is another image of NGC 5701:
This is a g-r-i (green-red-infrared) image, so it is somewhat false color. Red emission nebulae show up as green. There are at least two green splotches in the blueish ring surrounding the yellow bar and nucleus.

Ann

Whoa, Nelly That is an awfully big [slow to load] file, Ann.

Would you mind terribly changing it to this while you can still edit:

neufer wrote:[I'm not sure about your "little theory" , "Boomer12k" , but I do agree
that the Hoag's Object is just a distant example of M104 seen face on.

I don't see that at all. M104 is a slightly unusual spiral galaxy- the dust lane is more pronounced than usually seen, the central bulge is larger, but it is still pretty obviously a spiral, not far from normal. Hoag's object is structurally very different. It has a broad region almost completely devoid of normal matter. It has a dense central section like an elliptical galaxy, nothing like the halo seen on M104. And its outer ring is obviously evolved from (or evolving to) a spiral, and shows lots of star formation.

If I had to pick two galaxies that had less in common, I'd be hard pressed.

Could Hoag's Object actually be the result of gravitational lensing?

Goldtrend wrote:Could Hoag's Object actually be the result of gravitational lensing?

No.

Sorry, I don't see the M104 hypothesis. I see spiral arms all the way into the center. But here is UGC 7388 which appears to be a Hoags in the making. In this case it appears the process has just begun. Could it not be that the Hoags collider culprit is behind the central mass of yellow stars since we are looking down the tube so to speak.http://cas.sdss.org/astro/en/tools/char ... 3.66080825

Chris Peterson wrote:

neufer wrote:[I'm not sure about your "little theory" , "Boomer12k" , but I do agree
that the Hoag's Object is just a distant example of M104 seen face on.

I don't see that at all. M104 is a slightly unusual spiral galaxy- the dust lane is more pronounced than usually seen, the central bulge is larger, but it is still pretty obviously a spiral, not far from normal. Hoag's object is structurally very different. It has a broad region almost completely devoid of normal matter. It has a dense central section like an elliptical galaxy, nothing like the halo seen on M104. And its outer ring is obviously evolved from (or evolving to) a spiral, and shows lots of star formation.

If I had to pick two galaxies that had less in common, I'd be hard pressed.

Then we shall agree to disagree (once again).

neufer wrote:Then we shall agree to disagree (once again).

Hey, what if I don't want to agree to disagree? <g>

The inability to look at any galaxy (including our own) from more then one viewpoint is sure a serious limitation in studying them, at least using images.

stowaway wrote:Sorry, I don't see the M104 hypothesis.
I see spiral arms all the way into the center.

"Turtles all the way down?"

http://en.wikipedia.org/wiki/Sombrero_Galaxy wrote:
The Sombrero Galaxy (also known as M 104 or NGC 4594 ). See also:

* NGC 1291, a galaxy with an outer dust ring

* NGC 4725, a similar galaxy with an extended dust ring

* NGC 6027a, a member of Seyfert's Sextet with a very similar dust ring structure

* NGC 7742, a spiral galaxy with a similar dust ring