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Hubble Takes Pictures of Colliding Galaxies
Jerry Smith writes "The Register reports that the Hubble Space Telescope is still going strong, and took snapshots of two colliding galaxies. The sizes average between thousands and hundreds of thousand light years, containing ten million to one trillion stars. The process took hundreds of millions of years, and will take many more hundreds of millions of years."
You can find a really high resolution copy (3915x3885 as a TIFF or JPEG) of the image here. Hmm, this might make a pretty desktop wallpaper.
Um, none? I suppose I could try to think of some technological offshoot of current astrophysical science, but to be safe let's just round down to 0. Is this "practicality" the metric by which you think we ought to measure all scientific findings?
Can anyone explain what knowledge is gained from these pretty pictures?
Ah, now this is easier. Watching a close interaction between galaxies helps understand collisions we see happening further away, and tightens constraints on cosmological and galactic evolution models (the latter is what I worked on). Of course the pretty pictures are shown to the public --- we're far more interested in the high-resolution spectra of these regions. Starburst regions are of intense interest because of the degree to which the nebulae are enriched promptly with elements like sulfer, silicon, and oxygen (from high-mass, short-lived stars). Then when we see these bright regions in more distant galaxies with a certain ratio of elemental abundances we can make a guess as to the age of the region and perhaps the embedding galaxy. The spectra of many regions also gives us dynamic information about the system's interaction, yielding a good estimate of the total mass interacting gravitationally. We can use these more precise measurements to constrain galactic dark matter models and distributions. And I'm sure there are a hundred other areas of specialized research that will be influenced by high-resolution data of galactic collisions.
This is a very cool object, and because it's (relatively) close, it's visible to the human eyeball in a large amateur telescope, at a dark sky site (not QUITE like this Hubble image, obviously).
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I've tracked it down in my old 18" Newtonian/Dobsonian. With averted vision, you can see two "tails" twisting off the pair, much further out in the field than these Hubble images. Here's what it looks like in an amateur scope, but imagine it as just a dim hint in the eyepiece:
http://imgsrc.hubblesite.org/hu/db/1997/34/images
It's nothing at all like the Hubble image... just a hint of grey glow in the eyepiece, but still... there is something about seeing the actual photons from the object hitting your retina that's exciting, for us amateur astronomy geeks, anyway.