Astronomy Picture of the Day

NASA ^ | 11/090/09 | NASA, ESA and A. Evans

[sig226]

NGC 2623: Galaxy Merger from Hubble
Credit: NASA, ESA and A. Evans (Stony Brook) et al.

Explanation: Where do stars form when galaxies collide? To help find out, astronomers imaged the nearby galaxy merger NGC 2623 in high resolution with the Hubble Space Telescope in 2007. Analysis of this Hubble image and images of NGC 2623 in infrared light by the Spitzer Space Telescope, in X-ray light by XMM-Newton, and in ultraviolet light by GALEX, indicate that two originally spiral galaxies appear now to be greatly convolved and that their cores have unified into one active galactic nucleus (AGN). Star formation continues around this core near the above image center, along the stretched out tidal tails visible on either side, and perhaps surprisingly, in an off-nuclear region on the upper left where clusters of bright blue stars appear. Galaxy collisions can take hundreds of millions of years and take several gravitationally destructive passes. NGC 2623, also known as Arp 243, spans about 50,000 light years and lies about 250 million light years away toward the constellation of the Crab (Cancer). Reconstructing the original galaxies and how galaxy mergers happen is often challenging, sometimes impossible, but generally important to understanding how our universe evolved.

[Condor51]

Where do stars form when galaxies collide?

I'm not exactly sure. But I do know I don't want to be around when it happens.

(good thing I'll be loooong gone when the Andromeda Galaxy eats the Milky Way.)

[onedoug]

Intelligent life might still have made it a little more than halfway out on the right arm.

[sig226]

[cripplecreek]

I think that galaxies tend to pass through each other again and again till they combine. The distances between the individual stars are so great that science theorizes that actual collisions between stars is relatively rare. If we were still here when Andromeda and the milky way collide, its entirely possible that we would be unaffected.

[Condor51]

*** If we were still here when Andromeda and the milky way collide, its entirely possible that we would be unaffected. ***

True. Given that we're located way out in 'the suburbs' of the Milky Way it is 'possible'. But I wouldn't want to bet the rent on it.

However, if I recall correctly by the time Andromeda collides with the Milky Way, our Sun will already have grown into a Red Giant, fried Earth to a crisp, and then shrink down to a white dwarf.

[cripplecreek]

Yeah, I’m not going to lose any sleep over it.

I read somewhere not to long ago that one of the small satellite galaxies in our local group collided with the milky way in relatively recent times. (Recent being a billion or so years ago)