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

[Lilleulv]

The two colliding galaxies look like mirror images of one another. Do they turn i different directions or is that a just a visual effect? What will happen when they collide, will the spin come to a halt? Are they approching sideways (edge on) or will they collide disc on disc? Is there any way ot telling?

http://apod.nasa.gov/apod/ap090407.html

[Kesstra]

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?

[Dr. Skeptic]

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.

[rstevenson]

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

[orin stepanek]

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

If you blow up the picture you can see it is a galaxy! 8) That is if your looking at the object in the upper left hand corner.

Orin

[rstevenson]

So you're picking number 3, a "far-off galaxy with a very hot core"? (I should have said very bright core, since I don't know the temperature. ;-0 )

I did, of course, look at the picture blown up to 100% -- going larger just makes for larger pixels, not more information. I still couldn't tell.

But if it's a galaxy, it's probably cataloged. Any idea of the designation so I can try to look up a more detailed picture?

Rob

[twixter]

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.

[aristarchusinexile]

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

[bystander]

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.

[aristarchusinexile]

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.

[simonbrueck]

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

[Lilleulv]

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

[Lilleulv]

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.

[Chris Peterson]

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.

[Chris Peterson]

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.

[Chris Peterson]

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.

[bystander]

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.

[Chris Peterson]

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.

[Lilleulv]

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?

[rstevenson]

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

[rala]

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.

[Chris Peterson]

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.

[aristarchusinexile]

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.

[aristarchusinexile]

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.

[FrankTKO]

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?