Comments on: Collision of past and present

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Wed, 01 Dec 2010 06:33:59 +0000

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By: Jon Hanford

Jon Hanford — Tue, 30 Nov 2010 19:33:36 +0000

It’s really neat to pick out some of those young blue star clusters appearing in the tidal tail in the lower portion of the image. Also, a distant anonymous galaxy cluster appears to lie behind this tidal tail too. And finally, a ring galaxy (mebbe two!) appears to the right of the plume. An image taken with the Gemini North scope shows these features a bit better: http://www.gemini.edu/images/pio/20080825_ngc520_0001.jpg

And what do you know, Hubble Gotchu!: http://imgsrc.hubblesite.org/hu/db/images/hs-2008-16-bo-full_jpg.jpg (albeit upside down )

By: sophia8

sophia8 — Tue, 30 Nov 2010 13:15:22 +0000

As ever with these types of pictures, I’m wondering what this would look like from a planet in one of these galaxies. Makes me wish I had a Tardis to jump into.

By: Georg

Georg — Tue, 30 Nov 2010 10:59:05 +0000

Hello,
Mapnut is right, an appropriate word might be “interpenetrate”.
Georg

By: Georg

Georg — Tue, 30 Nov 2010 10:55:04 +0000

“Ah, Holmberg (1941). Definitely one of my favourite papers for the sheer ingenuity of doing the computation that way.”

Hello andy,
right! Analog calculators are ingenious, whereas digital
computing is brute force of large number of identical
and boring units.
Georg

By: Messier Tidy Upper

Messier Tidy Upper — Tue, 30 Nov 2010 04:55:13 +0000

Nice image and write-up thanks, BA.

@1. Mapnut :

I say we should refer to these events as mergers, not collisions (or train wrecks). Gives the public a more realistic, less sensationalist impression. For instance, what’ a layman going to think when he or she hears that the Milky Way will someday collide with the Andromeda?

Agreed. The media loves to sensationalise even “serious” science documentaries – as this favourite example :

http://blogs.discovermagazine.com/badastronomy/2009/10/26/felicia-day-collides-galaxies/

also involving galactic ~~collisions~~ mergers and M31 shows.

That said, I don’t think the ‘collision’ word is likely to disappear anytime soon & I don’t really mind it being used in this context given that it *is* an accurate description of at least the early part of the merger process. Some of the silly sensationalising nonsense that comes with that term though .. arrgh.

By: Jamey

Jamey — Tue, 30 Nov 2010 00:56:53 +0000

Honestly, I can see collisions superficially identical (at least to my eye) any time I want. It’s the Galaxy module in XScreensaver, and it shows this kind of thing – and all kinds of other results.

I’m only about 30% impressed by this, really.

By: Daniel J. Andrews

Daniel J. Andrews — Tue, 30 Nov 2010 00:42:31 +0000

Obviously, details are important, but sometimes you can get most of the way to your goal with just a few simplifications.

But models can’t simulate reality, it is just too complex, models are faulty, they just fudged the models to get what they wanted, there is no such thing as galactic merging….

By: Neil

Neil — Mon, 29 Nov 2010 21:44:00 +0000

“and in this case the two galaxies have probably been at it for 300 million years or so. They’re well on their way to merging”

BOW CHICKA BOW-BOW!!!

300 million years of foreplay! Reading about events on a galactic scale sure does make the actions of humans seem trivial by comparison!

By: andy

andy — Mon, 29 Nov 2010 20:34:16 +0000

Ah, Holmberg (1941). Definitely one of my favourite papers for the sheer ingenuity of doing the computation that way.

By: Mike Y.

Mike Y. — Mon, 29 Nov 2010 19:22:28 +0000

The earliest galaxy collision simulations didn’t even use computers. Holmberg in 1941 (http://adsabs.harvard.edu/abs/1941ApJ….94..385H) used light bulbs and photocells to imitate gravitational effects and modeled the collision between two “extragalactic nebulae” represented by 74 points. Ingenious, really. And his simulation showed that in some scenarios mergers are likely.

By: andy

andy — Mon, 29 Nov 2010 19:12:13 +0000

Elements of the past and the future combining to make something not quite as good as either…

By: chris j.

chris j. — Mon, 29 Nov 2010 19:02:41 +0000

i wouldn’t get too excited about the apparent similarity. after all, the team who modeled andromeda as a merger may have used ngc 520 to calibrate their model.

By: RickJ

RickJ — Mon, 29 Nov 2010 18:45:26 +0000

Actually there’s a lot more “debris” from the collision than is shown in this image. Just before I read this post I posted my reprocessed version of this collision taken at my home observatory to the Baut forum showing far more of the stars scattered by this collision.
http://www.bautforum.com/showthread.php/109921-Arp-157-A-major-smashup-reprocessed

I agree with BA it is a major train wreck as the galaxies will cease to exist as we knew them before. The evolution of the galaxies will be forever changed as well, they certainly won’t be on the same evolutionary track they were before.

Rick

By: Another Eric

Another Eric — Mon, 29 Nov 2010 17:45:59 +0000

Mapnut has a point. Collision evokes the impression of objects hitting each other, such as stars slamming into each other, destroying themselves and the galaxies. Merger describes what really happens.

By: Mapnut

Mapnut — Mon, 29 Nov 2010 17:23:33 +0000

Quote: “These galactic train wrecks can take billions of years to unfold, and in this case the two galaxies have probably been at it for 300 million years or so.”

That’s why I say we should refer to these events as mergers, not collisions (or train wrecks). Gives the public a more realistic, less sensationalist impression. For instance, what’ a layman going to think when he or she hears that the Milky Way will someday collide with the Andromeda?