galaxies colliding, NGC4013 (APOD 07 Feb 2008)
galaxies colliding, NGC4013 (APOD 07 Feb 2008)
When two galaxies collide, as with today's NGC 4013 and the Tidal Stream, do the component stars ever crash together, and if so, what is the result? Obviously the stars are far apart even in dense galaxies, but star-star collisions must occur just statistically.
- emc
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Re: galaxies colliding
hi memmd, Welcome to APOD!
http://apod.nasa.gov/apod/ap080207.html
A very interesting question...
8) I imagine it is many differences becoming a messy sameness until the samenesses are sorted back into some new differences
(Hope you're not offended, I like your question and I like to try and be funny when I don't have a clue
)
Hopefully someone else here knows the scientific answer![Idea :idea:](./images/smilies/icon_idea.gif)
... and what about the planetary orbits?
http://apod.nasa.gov/apod/ap080207.html
A very interesting question...
8) I imagine it is many differences becoming a messy sameness until the samenesses are sorted back into some new differences
![Wink :wink:](./images/smilies/icon_wink.gif)
![Embarassed :oops:](./images/smilies/icon_redface.gif)
Hopefully someone else here knows the scientific answer
![Idea :idea:](./images/smilies/icon_idea.gif)
... and what about the planetary orbits?
Last edited by emc on Thu Feb 07, 2008 2:59 pm, edited 3 times in total.
- JohnD
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memmd,
If you google for "when galaxies collide" (use the quotes), you will find a wealth of articles about this.
In the vastness of space, the probability of stellar collisions is as near zero as makes no difference, but the gas and dust of two galaxies will definitely collide. Shock waves, compression zones and new star forming ensues. Our own galaxy is thought to have consumed others in the past, presumably smaller ones as two equally sized spiral galaxies form an elliptical.
John
If you google for "when galaxies collide" (use the quotes), you will find a wealth of articles about this.
In the vastness of space, the probability of stellar collisions is as near zero as makes no difference, but the gas and dust of two galaxies will definitely collide. Shock waves, compression zones and new star forming ensues. Our own galaxy is thought to have consumed others in the past, presumably smaller ones as two equally sized spiral galaxies form an elliptical.
John
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Re: galaxies colliding
With the width of stars at light minutes and the separation at light years there is a disconnect of the order of a million!memmd wrote:When two galaxies collide, as with today's NGC 4013 and the Tidal Stream, do the component stars ever crash together, and if so, what is the result? Obviously the stars are far apart even in dense galaxies, but star-star collisions must occur just statistically.
In terms of a collisional cross section area that disconnect is of the order of a million squared!!
Since a galaxy is tens of thousands of light years across each star has about ten thousand separate chances of hitting this small relative cross section (of one over a million squared) or ten chances in a billion.
If you took off on the Starship Enterprise at warp speed through the center of the galaxy your chances of hitting a star are about the same as the chances of you eye seeing the surface of a star ... or in other words it is the ratio of the brightness of the Milky Way to the brightness of the surface of the sun. (Olber's paradox)
Thus out of a galaxy of a 100 billion stars only about a thousand will engage a direct collision and unless one of those thousand stars is your sun this will be important only in terms of the gravitational radiation generated by the galactic collision.
Art Neuendorffer
Quite a while ago I read where a scientist answered your question in this fashion. I am not sure the exact words but the jist was this:
"the odds of stars crashing together in two colliding Galaxies are the odds of two mosquitoes placed at opposite ends of the Grand Canyon eventually crashing into each other.... and forming an avocado."
"the odds of stars crashing together in two colliding Galaxies are the odds of two mosquitoes placed at opposite ends of the Grand Canyon eventually crashing into each other.... and forming an avocado."
npsguy
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We may get a close hand look in about 3 billion years.
http://www.cita.utoronto.ca/~dubinski/tflops/
Don't be mislead by the first impression of the webpage title![Wink :wink:](./images/smilies/icon_wink.gif)
http://www.cita.utoronto.ca/~dubinski/tflops/
Don't be mislead by the first impression of the webpage title
![Wink :wink:](./images/smilies/icon_wink.gif)
Last edited by emc on Thu Feb 07, 2008 4:46 pm, edited 1 time in total.
response
Thank you for these comments. I did Google as suggested and initially found this site from Cornell if anyone is interested:
http://curious.astro.cornell.edu/questi ... number=382
I am sure the odds of star collision are very, very low, but considering the billions of stars over billions of years, it must have happened more than once.[/url]
http://curious.astro.cornell.edu/questi ... number=382
I am sure the odds of star collision are very, very low, but considering the billions of stars over billions of years, it must have happened more than once.[/url]
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Great picture.
In the large version, I noticed quite a few other features that were either too small to resolve in the small version, or cropped off, including numerous distant galaxies and some colorful nebulae. In particular, I was fascinated by what appears to be a blue-ish reflection nebula at about 5 O'clock from NGC 4013.
At 1 O'clock, there is a small swept-looking blue and yellow feature. I wonder if it could be a younger version of NGC 4013, with star formation still rapidly occurring in the tidal stream?
In the large version, I noticed quite a few other features that were either too small to resolve in the small version, or cropped off, including numerous distant galaxies and some colorful nebulae. In particular, I was fascinated by what appears to be a blue-ish reflection nebula at about 5 O'clock from NGC 4013.
At 1 O'clock, there is a small swept-looking blue and yellow feature. I wonder if it could be a younger version of NGC 4013, with star formation still rapidly occurring in the tidal stream?
"Any man whose errors take ten years to correct is quite a man." ~J. Robert Oppenheimer (speaking about Albert Einstein)
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Re: response
Another aspect to consider about colliding galaxies:memmd wrote:Thank you for these comments. I did Google as suggested and initially found this site from Cornell if anyone is interested:
http://curious.astro.cornell.edu/questi ... number=382
I am sure the odds of star collision are very, very low, but considering the billions of stars over billions of years, it must have happened more than once.[/url]
http://antwrp.gsfc.nasa.gov/apod/ap060824.html
Art Neuendorffer
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Not necessarily. Mathematically, it is possible to add an infinite number of finite numbers, and end up with a sum that is finite.
For example, the series 1/n^2 (1 + 1/4 + 1/9 + 1/6 +...) if carried out to n=infinity only adds up to pi^2/6.
Also, the universe is not, according to the big bang theory, thought to be infinite.
For example, the series 1/n^2 (1 + 1/4 + 1/9 + 1/6 +...) if carried out to n=infinity only adds up to pi^2/6.
Also, the universe is not, according to the big bang theory, thought to be infinite.
"Any man whose errors take ten years to correct is quite a man." ~J. Robert Oppenheimer (speaking about Albert Einstein)
this site from Cornell
As a very minor note, the site I noted is an answer to the same question I asked, but from a 7th Grade student. It's nice to know I am keeping up with a 12 year old. ![Smile :)](./images/smilies/icon_smile.gif)
![Smile :)](./images/smilies/icon_smile.gif)
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But we can 'see' the wrinkly plasma left over 380,000 years after the 4D origin:emc wrote:Not that it is or isn't, but how do we prove the universe is finite since we are looking outwardly back in time and cannot 'see' the 4D origin?iamlucky13 wrote: Also, the universe is not, according to the big bang theory, thought to be infinite.
http://antwrp.gsfc.nasa.gov/apod/ap061007.html
http://antwrp.gsfc.nasa.gov/apod/ap050925.html
http://antwrp.gsfc.nasa.gov/apod/ap060323.html
http://antwrp.gsfc.nasa.gov/apod/ap070827.html
Art Neuendorffer
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The universe that is visible to us in the electromagnetic spectrum is finiteemc wrote:Thanks for the links! You are very helpful and patient!
So the wrinkly plasma proves the universe is finite?
(assuming there are no wormholes around through which one can actually travel to a different universe).
Art Neuendorffer
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What about the 4D origin that we can't see??? Is the 4D source inferred or somehow defined from the known physical spectrums?neufer wrote:The universe that is visible to us in the electromagnetic spectrum is finite.
Well, there is a big hole according to WMAPneufer wrote:(assuming there are no wormholes around through which one can actually travel to a different universe).
![Smile :)](./images/smilies/icon_smile.gif)
- emc
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Art, (hope I'm not being too presumptuous) (cool first name)
Seems my 4D source question may be answered in the "'Hole in the Universe' possible explanation" Asterisk thread... the 4D source is inferred if I understand enough of what I read. This was my initial understanding from my Asterisk conversation with another physicist in a different thread. In my question to you, I was looking for validation of my understanding of what scientists believe about the origin of the universe.
For me, the scientific belief in a 4D source is similar to belief in a supreme being, as neither can be seen or quantifiably measured and both exist (by faith) outside of time and space. At least for myself, this gives me more hope and adds to our common ground... which I think is very cool
8)
Seems my 4D source question may be answered in the "'Hole in the Universe' possible explanation" Asterisk thread... the 4D source is inferred if I understand enough of what I read. This was my initial understanding from my Asterisk conversation with another physicist in a different thread. In my question to you, I was looking for validation of my understanding of what scientists believe about the origin of the universe.
For me, the scientific belief in a 4D source is similar to belief in a supreme being, as neither can be seen or quantifiably measured and both exist (by faith) outside of time and space. At least for myself, this gives me more hope and adds to our common ground... which I think is very cool
![Very Happy :D](./images/smilies/icon_biggrin.gif)