Andromeda Galaxy is a Cannibal

[Solauren]

Mmmm.... tastes like Nebula

Astronomers prove next-door galaxy Andromeda is cannibal by finding 'partly digested remains'
Module body

By Seth Borenstein, The Associated Press

WASHINGTON - Earth's nearest major galactic neighbour is a cosmic cannibal. And it is heading this way.

Astronomers have long suspected that Andromeda is a space predator, consuming dwarf galaxies that wander too close. Now, cosmic detectives are doing a massive search of the neighbourhood and have found proof of Andromeda's sordid past: They have spotted leftovers in Andromeda's wake.

Early results of a massive telescope scan of Andromeda and its surroundings found about a half-dozen remnants of Andromeda's galactic appetite. Stars and dwarf galaxies that got too close to Andromeda were ripped from their usual surroundings.

"What we're seeing right now are the signs of cannibalism," said the study's lead author Alan McConnachie of the Herzberg Institute of Astrophysics in Victoria, British Columbia. "We're finding things that have been destroyed; ... partly digested remains."

Their report is published in Thursday's edition of the journal Nature.

Andromeda and the Milky Way, Earth's galaxy, are the two big dogs of this galactic neighbourhood. Andromeda is the closest major galaxy, about 2.5 million light years away. A light year is about 5.9 trillion miles. The massive mapping of Andromeda is looking half a million light years around Andromeda.

Astronomers have known for decades that galaxies consume each other, sometimes violently, sometimes just creating new mega-galaxies. But this study is different because "of the scale of the cannibalism, and we've found evidence directly in front of our eyes," said co-author Mike Irwin, an astrophysicist at the University of Cambridge in England.

This type of galactic crash is common, and the paper makes sense, said Harvard astronomer Mark Reid, who was not part of the Andromeda mapping team. And just because Andromeda consumes a galaxy, it does not make the victim disappear, he said.

The cannibalistic behaviour often just strips stars from where they had been, rearranging the night sky. Most of a galaxy is empty space, so there is little if any crashing of stars and planets going on, Irwin said.

"It would be a beautiful night sky," he said. "It would be quite spectacular."

The once and future main victim of Andromeda is a dwarf galaxy that circles it called Triangulum.

Eventually, in about 3 billion years, Triangulam, which once came too close to Andromeda and was stripped of some stars, will spiral into Andromeda, about the same time it comes crashing into Earth's galaxy, said study co-author John Dubinksi of the University of Toronto.

The Milky Way and Andromeda are heading toward each other at about 75 miles per second. They are so far away from each other that the big crash is a few billion years away. And even that might be nothing more than a reshuffling of the night sky or the creation of one super-sized galaxy, McConnachie said.

I think it's fascinating that the Milky Way, Andromeda and Triangulam will all 'collide' at about the same time.

[General Zod]

It's almost too bad that by the time it happens nobody here will be alive to see it.

[ThomasP]

M33/Triangulum is a dwarf galaxy? I'd thought it on par with the Milky Way and Andromeda for some reason.

[Ford Prefect]

M33/Triangulum is a dwarf galaxy? I'd thought it on par with the Milky Way and Andromeda for some reason.

From memory it's bigger than every other galaxy in our local group, but significantly smaller than either the Milky Way or Andromeda.

[Solauren]

It's almost too bad that by the time it happens nobody here will be alive to see it.

Yeah. i don't think you could revive someone cyrogenically frozen for several billion years.

Too bad eh?

[NoXion]

It's almost too bad that by the time it happens nobody here will be alive to see it.

Yeah. i don't think you could revive someone cyrogenically frozen for several billion years.

Too bad eh?

I hear that's because of radiation damage due to naturally occuring isotopes within the human body. Might it not be possible to stretch things out a bit by occasionally reviving the human popsicle(s) in question, so that the body's healing processes can repair the damage?

[starslayer]

From memory it's bigger than every other galaxy in our local group, but significantly smaller than either the Milky Way or Andromeda.

Correct, but no astronomer worth his salt would call M33 a dwarf galaxy. It has very advanced and distinct spiral structure (class Sc), and is quite massive, although only about 1/10 as massive as M31 or the Milky Way. A true dwarf galaxy looks something like this.

However, no other "Triangulum dwarf" exists to my knowledge. I had no idea M33 would join the M31/MW crash party. Quite interesting.

[Junghalli]

Yeah. i don't think you could revive someone cyrogenically frozen for several billion years.

Too bad eh?

Theoretically if you could solve the aging problem there's probably no reason you couldn't survive an arbitrary amount of time (until the universe becomes too entropic to support human life at any rate), but given the limited storage capacity of the human brain you almost certainly wouldn't remember anything of your present life by then. This problem might be solved by keeping you unconscious for most of that time, although if the neural pathways atrophy after a long time unconscious some artificial intervention might be required there to freeze the neural pathways where they are. Staying cryo-frozen with short periods of "mere" unconsciousness every couple of decades to allow the radiation damage in your body to be repaired might not be a bad approach. Of course, you must trust that the systems that keep you in this state will survive billions of years, which is a nontrivial issue, to put it mildly. Uploading into a machine is another possibility if you're really serious about wanting to survive into deep time with your present self still intact (it would be buried under billions of years of new experience but as long as you have access to sufficient hardware there's no reason you couldn't give yourself perfect memory retention and recall, and if you desired you could even maintain a copy of your present self as a separate subsystem to be brought online only for exceptionally noteworthy events).