Starship Asterisk*

by **rstevenson** » Thu Apr 09, 2009 4:05 pm

Thanks Chris. I've now bookmarked SIMBAD.

What caught my eye was that this object has such a well-defined (at least at this scale) center. Could be just an illusion of course, perhaps a ring of dust in the galaxy giving this impression.

by **Chris Peterson** » Thu Apr 09, 2009 2:39 pm

rstevenson wrote:I asked way up in this thread about that small orange dot surrounded by fuzzy stuff which is to the top-left of the two main galaxies in this image. From this image I can't see whether it's a closer star which happens to be in front of a distant galaxy, or if it's perhaps a planetary nebula which happens to be in our line of site, or if it's a distant galaxy with a bright, well-defined central region. Since I'm in no way an astronomer, I wonder how one can find out more about such an object. If you were interested in it, how would you go about tracking down more info, or even if any other image of it exists?

It's definitely a galaxy. In fact, if you look around it, you can see dozens of distant galaxies. On very deep shots like this, except for a few foreground stars (which usually show diffraction spikes), it's likely that every little speck you can see is a galaxy or a globular cluster. Individual stars don't show up at this scale unless they are in our own galaxy.

I would try tracking down an object like this using something like SIMBAD. However, when I do that using the approximate coordinates of 14h 35m 10s, +5° 21m 48s, that little galaxy doesn't show up. It's very likely that it hasn't been cataloged at all.

by **rstevenson** » Thu Apr 09, 2009 11:24 am

Hi Chris,

It seems we were both responding almost simultaneously to the question above our two responses. But now that I have your attention ...

I asked way up in this thread about that small orange dot surrounded by fuzzy stuff which is to the top-left of the two main galaxies in this image. From this image I can't see whether it's a closer star which happens to be in front of a distant galaxy, or if it's perhaps a planetary nebula which happens to be in our line of site, or if it's a distant galaxy with a bright, well-defined central region. Since I'm in no way an astronomer, I wonder how one can find out more about such an object. If you were interested in it, how would you go about tracking down more info, or even if any other image of it exists?

Thanks for any hints you can offer.

Rob

by **Chris Peterson** » Thu Apr 09, 2009 3:14 am

rstevenson wrote:As I mentioned above, there is a note on another site which says the galaxies may not be interacting in the sense of "colliding". Since you may not have seen the link, here is a quote from that page...

Arp 274 was previously thought to be a set of interacting galaxies, galaxies that are "colliding" and gravitationally affecting one another. The [earlier] ground-based image ... of the same area of the sky certainly makes it seem that way. But, the new image by the Hubble, with far more detail, reveals that the three galaxies may just be galaxies located near each other, but not interacting together. The largest galaxy in the center, a barred spiral galaxy, appears to be extending an arm into the other spiral galaxy, on the right. Distortion of the shapes of the galaxies by gravity would indicate interaction, but this is simply not exhibited by these galaxies.
It would be interesting to see the galaxies "now" to see how close they have gotten. I assume various researchers are working with these images in more detail and answers will be forthcoming eventually.

I agree that an interaction between the galaxies isn't obvious. This goes to what I said earlier, that usually the only way to tell for certain is with careful redshift measurements, and even then there could be significant uncertainty. If you don't see clear tidal distortion (which isn't obvious here), it is really hard to tell if galaxies are interacting.

by **rstevenson** » Thu Apr 09, 2009 1:59 am

As I mentioned above, there is a note on another site which says the galaxies may not be interacting in the sense of "colliding". Since you may not have seen the link, here is a quote from that page...

Arp 274 was previously thought to be a set of interacting galaxies, galaxies that are "colliding" and gravitationally affecting one another. The [earlier] ground-based image ... of the same area of the sky certainly makes it seem that way. But, the new image by the Hubble, with far more detail, reveals that the three galaxies may just be galaxies located near each other, but not interacting together. The largest galaxy in the center, a barred spiral galaxy, appears to be extending an arm into the other spiral galaxy, on the right. Distortion of the shapes of the galaxies by gravity would indicate interaction, but this is simply not exhibited by these galaxies.

It would be interesting to see the galaxies "now" to see how close they have gotten. I assume various researchers are working with these images in more detail and answers will be forthcoming eventually.

Rob

by **Chris Peterson** » Thu Apr 09, 2009 1:58 am

FrankTKO wrote:We all know these collisions happens over a very long period of time, hundred of millions of years as stated in the caption. But these two are 400 millions light years away; is that collision already over?

It depends on how you define "now": there really are different functional definitions. Certainly, by one that considers the time of flight of light, the collision is much more advanced than what we are currently seeing. From a practical standpoint, "now" meaning when we make the observation is almost always the more useful definition.

by **FrankTKO** » Thu Apr 09, 2009 1:48 am

We all know these collisions happens over a very long period of time, hundred of millions of years as stated in the caption. But these two are 400 millions light years away; is that collision already over?

by **aristarchusinexile** » Wed Apr 08, 2009 7:23 pm

Chris Peterson wrote:
aristarchusinexile wrote:The very faint, small, horizontal spiral galaxy at the bottom right is drawing the outermost arm of the large galaxy on the right.
I don't see any such interaction. And given that the small galaxy is far away, there's no reason to expect any.

You need to be careful with visual observations like that. Arp got himself into hot water by seeing connections that didn't exist. You can really only rely on instrumented measurements of redshift to determine if galaxies are interacting. We're just too good at seeing patterns where none exist to trust our visual interpretations.

Some of us, I should say most of us including myself, are good at ignoring what's plainly visible before our eyes .. especially if our minds are programmed by institutionalized education which severely restricts our senses in order to enhance the program's ability to distort reality in such a way as to blind the mind to enhance the achievement of the goals of Babylon's New World Order which is in reality the same Old World Order established by Cain's murder of his brother. However, "We shall overcome" is clearly written in the stars.

by **aristarchusinexile** » Wed Apr 08, 2009 7:15 pm

simonbrueck wrote: Wide open
In its center incredible information
Enshrined in a singularity of a billion suns
Opening wide
Floating majesty
Accelerating to speed until they merge
For millions and Millions of years
Planets torn away from their suns into deep space
Suns merging their dust in gravitational attraction
New planetary disks distorted, forming
Explosions of Supernovas
But the true majesties in the middles centers nuclei singularities
Attraction by definition, attraction pure
Flying towards another accompanied by flocks of suns and star clouds
Accelerating to speeds which make blush the light
Accelerating so that space changes its very nature
The event horizons invisible distortion
Unification
2 seconds of power equal to all the galaxies, to all the stars
just two seconds
a singular message to all of us but who who who to?
Billions of suns and planets merging their basic message
Spreading it out
Life
Spirit
Creation
Creator

An excellent example of modern poetry with great potential but without rhyme, rhythm, cadence, colour .. all of the things which make great poetic light. Nevertheless, the poem would probably be scored highly by modern-minded critics schooled in the post World War Two era of darkness of mind.

by **Chris Peterson** » Wed Apr 08, 2009 1:30 pm

rala wrote:Sorry to nag about the subject of Colliding spiral Galaxies of Arp 274: But there is something which I would like to know:
Do I see this correct: the colliding spiral galaxies have different directions. One clockwise, the other counterclockwise. ?
:| And provided I am seeing this correct, what explanation would be for this?
Thanks for helping me with my questions.

From a galaxy's point of view, there is no such thing as clockwise or counterclockwise. That's just a distinction we make based on which side we're seeing them from. Throw a thousand pennies on the floor, half will be heads, half tails. In other words, the fact that these two galaxies are rotating in different directions from our point of view means nothing at all, and needs no explanation.

by **rala** » Wed Apr 08, 2009 12:53 pm

Sorry to nag about the subject of Colliding spiral Galaxies of Arp 274: But there is something which I would like to know:
Do I see this correct: the colliding spiral galaxies have different directions. One clockwise, the other counterclockwise. ?

And provided I am seeing this correct, what explanation would be for this?
Thanks for helping me with my questions.

by **rstevenson** » Tue Apr 07, 2009 8:16 pm

Elsewhere on the web today, there's a note* saying that these three galaxies, previously assumed to be interacting, may just be close neighbours, especially from our point of view, and may not be interacting at all (any more than Andromeda and ours are interacting, which is to say, weakly at the moment.)

Rob

* http://astronomyandspace.blogspot.com/2 ... p-274.html

by **Lilleulv** » Tue Apr 07, 2009 6:50 pm

Chris Peterson wrote:
bystander wrote:
Chris Peterson wrote:I doubt they're on the same plane, but agree they are not terribly far from it. ...
Not very far indeed. Towards the top, it appears the left side galaxy is in front, towards the bottom, the right side galaxy seems nearer. I'm aware appearances can be deceiving, but look at the overlapping spiral arms.
I don't see it that way (if I'm understanding you). My sense is that we're looking down on the spine of a book propped open on a table, with one galaxy on each cover, and the two intersecting along the spine- primarily seen in the interacting arms at the top. The two galaxy planes could easily be tilted tens of degrees with respect to each other.

However, this is just my visual impression, and I don't put much trust in it. I assume that the actual orientations of these galaxies are known from actual measurements, but that information isn't included with the APOD text.

Are all galaxies circular of shape if viewed at 90 degrees from above the disc? If so, the left hand galaxy appeares to be tilted 20 or maybe 30 degrees. But I can see no evidence of deforming spiral arms even though they appear to be colliding. Could the galaxy on the right be further away, and behind the one on the left?

by **Chris Peterson** » Tue Apr 07, 2009 6:20 pm

bystander wrote:
Chris Peterson wrote:I doubt they're on the same plane, but agree they are not terribly far from it. ...
Not very far indeed. Towards the top, it appears the left side galaxy is in front, towards the bottom, the right side galaxy seems nearer. I'm aware appearances can be deceiving, but look at the overlapping spiral arms.

I don't see it that way (if I'm understanding you). My sense is that we're looking down on the spine of a book propped open on a table, with one galaxy on each cover, and the two intersecting along the spine- primarily seen in the interacting arms at the top. The two galaxy planes could easily be tilted tens of degrees with respect to each other.

However, this is just my visual impression, and I don't put much trust in it. I assume that the actual orientations of these galaxies are known from actual measurements, but that information isn't included with the APOD text.

by **bystander** » Tue Apr 07, 2009 6:09 pm

Chris Peterson wrote:I doubt they're on the same plane, but agree they are not terribly far from it. ...

Not very far indeed. Towards the top, it appears the left side galaxy is in front, towards the bottom, the right side galaxy seems nearer. I'm aware appearances can be deceiving, but look at the overlapping spiral arms.

This was my choice for Hubble's Next Discovery. I'm not disappointed, great picture.

by **Chris Peterson** » Tue Apr 07, 2009 5:59 pm

aristarchusinexile wrote:The very faint, small, horizontal spiral galaxy at the bottom right is drawing the outermost arm of the large galaxy on the right.

I don't see any such interaction. And given that the small galaxy is far away, there's no reason to expect any.

You need to be careful with visual observations like that. Arp got himself into hot water by seeing connections that didn't exist. You can really only rely on instrumented measurements of redshift to determine if galaxies are interacting. We're just too good at seeing patterns where none exist to trust our visual interpretations.

by **Chris Peterson** » Tue Apr 07, 2009 5:55 pm

twixter wrote:I got hung up on the statement "When two galaxies collide, the stars that compose them usually do not." This is somewhat ambiguous. One interpretation, which seems more likely, is that for any specific star in either galaxy, it is unlikely that that star will collide with another. A more literal interpretation is that throughout both galaxies, it is unlikely that any two stars will collide. IF that is what was meant, is there any statistical basis for such a claim? Do computer models contain as many stars as the actual galaxies contain? Do these models allow for the possibility of a collision? If an event with an extremely unlikely outcome is repeated often enough, at some point it becomes likely.

There are simulations with large numbers of stars that show an absence of collisions. But you don't really need such models- it can be worked out with some fairly basic statistical calculations. I had to do that for the case of a large globular cluster back when I was in college. You can take two clusters like M13 and pass them back and forth through each other several hundred times before you would get a single collision. Clusters (and galaxies) are mainly empty space.

The caption should be interpreted as meaning that a very small number of stars will actually collide- in fact, it is likely that no stars will collide. However, two stars passing within a light year or less of each other- which will be much more common- could easily result in the disruption of their planetary systems.

by **Chris Peterson** » Tue Apr 07, 2009 5:47 pm

Kesstra wrote:What intrigues me is that they both look like they are on the same plane. So say in one of those galaxies there is a planet with civilization who are about advanced as we are. When they look out do they know that there is another galaxy next to them OR would they think they were looking across a huge vast galaxy, thinking it was only one galaxy?

I doubt they're on the same plane, but agree they are not terribly far from it. If somebody in those galaxies had our level of science and technology, they would probably be aware that they were in the middle of a galactic collision. We've learned a lot about the structure of our own galaxy in recent years by observing it at wavelengths where we can see very far (radio and IR), and also by looking at a lot of redshifts (Doppler redshift in this case) to figure out the actual motions of stars, which tell us a lot about mass and dynamics. If we applied those same tools from inside these colliding galaxies, we'd see the odd dynamics, and we'd probably also see the existence of two galactic cores, complete with their supermassive black holes.

by **Lilleulv** » Tue Apr 07, 2009 5:01 pm

rstevenson wrote:There's an interesting looking object to the top-left of the two main protaganists in this picture. See the hot little orange spot inside a swirl of something? I can't tell whether that might be a star coincidentally in front of a far off galaxy, or the glowing centre of a relatively nearby nebula, or a far-off galaxy with a very hot core, or ... ...

Anyone know what it is? And more generally, how does one go about finding out such things without asking here? That is, if you can answer the question, how did you know?

Thanks for a great forum for us closet nerds.

Rob

Could it be a planetary nebula? The glowing object in the centre looks well defined and star-like, not fuzzy like one would expect from a galaxy. Quite redish color too.

by **Lilleulv** » Tue Apr 07, 2009 4:54 pm

Dr. Skeptic wrote:http://www.galaxydynamics.org/spiral_metamorphosis.html

Here is a source of some animations to help answer your questions. Science and art at the same time.

Looks like the galaxies are behaving much like smoke when they collide

by **simonbrueck** » Tue Apr 07, 2009 4:34 pm

Wide open
In its center incredible information
Enshrined in a singularity of a billion suns
Opening wide
Floating majesty
Accelerating to speed until they merge
For millions and Millions of years
Planets torn away from their suns into deep space
Suns merging their dust in gravitational attraction
New planetary disks distorted, forming
Explosions of Supernovas
But the true majesties in the middles centers nuclei singularities
Attraction by definition, attraction pure
Flying towards another accompanied by flocks of suns and star clouds
Accelerating to speeds which make blush the light
Accelerating so that space changes its very nature
The event horizons invisible distortion
Unification
2 seconds of power equal to all the galaxies, to all the stars
just two seconds
a singular message to all of us but who who who to?
Billions of suns and planets merging their basic message
Spreading it out
Life
Spirit
Creation
Creator

by **aristarchusinexile** » Tue Apr 07, 2009 3:04 pm

bystander wrote:
aristarchusinexile wrote:The very faint, small, horizontal spiral galaxy at the bottom right is drawing the outermost arm of the large galaxy on the right.
That galaxy is probably far in the background and not involved in any interaction.

True, Bystander, it seems very far in the background .. but its gravitation must be exceptional because if you examine the end of the arm of the large galaxy on the right it obviously is drawn towards that faint spiral. The strength of the action of that faint spiral is to me one of the most peculiar effects I've seen on apod.

by **bystander** » Tue Apr 07, 2009 2:51 pm

aristarchusinexile wrote:The very faint, small, horizontal spiral galaxy at the bottom right is drawing the outermost arm of the large galaxy on the right.

That galaxy is probably far in the background and not involved in any interaction.

by **aristarchusinexile** » Tue Apr 07, 2009 2:49 pm

The very faint, small, horizontal spiral galaxy at the bottom right is drawing the outermost arm of the large galaxy on the right.

by **twixter** » Tue Apr 07, 2009 2:29 pm

I got hung up on the statement "When two galaxies collide, the stars that compose them usually do not." This is somewhat ambiguous. One interpretation, which seems more likely, is that for any specific star in either galaxy, it is unlikely that that star will collide with another. A more literal interpretation is that throughout both galaxies, it is unlikely that any two stars will collide. IF that is what was meant, is there any statistical basis for such a claim? Do computer models contain as many stars as the actual galaxies contain? Do these models allow for the possibility of a collision? If an event with an extremely unlikely outcome is repeated often enough, at some point it becomes likely.

Starship Asterisk*

The Colliding Spiral Galaxies of Arp 274 (2009 April 7)

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