Galactic Cannibalism and life on Extra-Galactic solar system

[Bilbo]

When galactic cannibalism happens like what will eventually happen between our galaxy and Andromeda the spiraling effects can do may things.

One thing that can happen is that suns, planets, or entire solar systems can be flung out from both galaxies off into the void between galaxies.

Now assuming an entire solar system similiar to our own was cast out would it be possible for life to form on such a solar system?


As far as I understand things not being in a galaxy will not take anything away of relevance. The night sky would be fascinating compared to our own. No stars out there. Thought the spiraling Andromeda and Milkyway would make an awesome sight.

[Singular Intellect]

If our solar system maintained it's stable formation (ie: oribits, make up, etc), being flung into intergalactic space could be argued as potentially a good thing.

You're no longer surrounded by so much hazardous material and activity.

Does make travelling to the next star a bit more of a bitch though...

[Bilbo]

One thing I was thinking is that being flung out might be a good thing in that two galaxies colliding will awaken the super masive blackholes at the center of each. These two will then spew out high energy jets that will be very bad if it hurt your neck of the woods.

[Lord of the Abyss]

Another worry, as I recall, is that the interpenetration will cause a large upsurge in star formation. Lots of new stars means lots of supernovas as the big, short lived ones die. Being tossed out of the galaxy could be safer for that reason as well.

On the other hand, being tossed out at the wrong angle could make things worse if the central black hole flares up - the galactic disc acts as a shield.

[Kuroneko]

It most probably would be an unfortunate turn of events for the star system. Life could still form--external stellar objects have no abiogenic relevance after the formation of the system and provide negligible evolutionary pressure (some of the nights being darker than usual might have some effect, though the presence or absence of moons would be more important).

If our solar system maintained it's stable formation (ie: oribits, make up, etc), being flung into intergalactic space could be argued as potentially a good thing. You're no longer surrounded by so much hazardous material and activity.

What are you referring to?

Does make travelling to the next star a bit more of a bitch though...

Indeed. Hence, a loss for any intelligence that might evolve on it.

One thing I was thinking is that being flung out might be a good thing in that two galaxies colliding will awaken the super masive blackholes at the center of each. These two will then spew out high energy jets that will be very bad if it hurt your neck of the woods.

I'm not sure about that. It seems like supermassive black holes should actually be less dangerous, e.g., Sgr A* at our own galaxy has a radius of order 1E10m, completely dwarfing most stars. Even geometrically speaking, they would be more likely to swallow up stars without performing much violence; additionally, their tidal forces even near the horizon would be much lower (for Sgr A*, less than 1E-4 g per meter), leading to less friction and hence less electromagnetic radiation. Collisions between individual stars would be far worse, and if a full-size gamma-ray burst happened to form in a disadvantageous direction, it's dubitable that the distances involved would protect the system adequately. Fortunately, collisions should be rather unlikely.

[Bilbo]

I'm not sure about that. It seems like supermassive black holes should actually be less dangerous, e.g., Sgr A* at our own galaxy has a radius of order 1E10m, completely dwarfing most stars. Even geometrically speaking, they would be more likely to swallow up stars without performing much violence; additionally, their tidal forces even near the horizon would be much lower (for Sgr A*, less than 1E-4 g per meter), leading to less friction and hence less electromagnetic radiation. Collisions between individual stars would be far worse, and if a full-size gamma-ray burst happened to form in a disadvantageous direction, it's dubitable that the distances involved would protect the system adequately. Fortunately, collisions should be rather unlikely.

I was under the impression that the danger was that when the Milky Way and Andromeda start to dance before collision the gravy from each will start to throw additional dust and gast towards the two super massive black holes. This massive increase in food is what would cause them to awaken and create the massive jets of particles.

[GrandMasterTerwynn]

When galactic cannibalism happens like what will eventually happen between our galaxy and Andromeda the spiraling effects can do may things.

One thing that can happen is that suns, planets, or entire solar systems can be flung out from both galaxies off into the void between galaxies.

Just stars/star systems. While the space between galaxies is relatively crowded, galaxies themselves are largely empty space. Take the example of the Milky Way and the Andromeda Galaxy. The diameter of each one is roughly 4% of the distance separating them. Now take the center of the galaxy, where the average separation between stars is something like a light-year. The diameter of a Sun-sized star, with respect to the distance to it's closest neighbor in that case, is 0.00001% of that distance. For a whole solar system (discounting the Oort Cloud,) it's 0.1%. Remember, that is the worst-case scenario.

In other words, while galactic collisions are common, the effect is like mixing two clouds of smoke. The smoke particles don't collide.

Now assuming an entire solar system similiar to our own was cast out would it be possible for life to form on such a solar system?

There's no reason life shouldn't form, because it's extraordinarily unlikely that the galactic collision will cause a stellar collision.

[Kuroneko]

I was under the impression that the danger was that when the Milky Way and Andromeda start to dance before collision the gravy from each will start to throw additional dust and gast towards the two super massive black holes. This massive increase in food is what would cause them to awaken and create the massive jets of particles.

That might happen. I'd guess that this would happen over a long enough period and with low enough friction so as to not emit with great enough power, but I haven't done any calculations nor seen any studies in that regard, so I don't know.

[Singular Intellect]

If our solar system maintained it's stable formation (ie: oribits, make up, etc), being flung into intergalactic space could be argued as potentially a good thing. You're no longer surrounded by so much hazardous material and activity.

What are you referring to?

Supernovas, massive gamma ray bursts, non local asteroids and comets with potential impact danger, etc.

[Samuel]

If our solar system maintained it's stable formation (ie: oribits, make up, etc), being flung into intergalactic space could be argued as potentially a good thing. You're no longer surrounded by so much hazardous material and activity.

What are you referring to?

Supernovas, massive gamma ray bursts, non local asteroids and comets with potential impact danger, etc.

Not to mention having two galaxies collide could result in an active galaxy, with the central black hole spewing out tons of radiation. Needless to say, it is good to be as far way as possible from that.

[starslayer]

Milkomeda will most likely not be an active galaxy; both the Milky Way and Andromeda are for the most part relatively quiescent elder statesmen type galaxies, or will be once the merger starts and happens. And besides, the jets go out of disk in a "polar" direction; if the Sun, or any other life-bearing star, is ejected, it most likely will remain very, very far away from the jets and any radiation danger.

That might happen. I'd guess that this would happen over a long enough period and with low enough friction so as to not emit with great enough power, but I haven't done any calculations nor seen any studies in that regard, so I don't know.

For most mergers, this is in fact correct. AGN are very rare nowadays, and even quasars and such eventually exhaust their fuel. The movies I've seen produced by the astronomy department here (here's one) show that really, not much happens on a small scale.

Supernovas, massive gamma ray bursts, non local asteroids and comets with potential impact danger, etc.

In any non-starburst/non-active galaxy's habitable zone, these are rare enough as to not pose much of a problem.

I'm not sure about that. It seems like supermassive black holes should actually be less dangerous, e.g., Sgr A* at our own galaxy has a radius of order 1E10m, completely dwarfing most stars. Even geometrically speaking, they would be more likely to swallow up stars without performing much violence; additionally, their tidal forces even near the horizon would be much lower (for Sgr A*, less than 1E-4 g per meter), leading to less friction and hence less electromagnetic radiation. Collisions between individual stars would be far worse, and if a full-size gamma-ray burst happened to form in a disadvantageous direction, it's dubitable that the distances involved would protect the system adequately. Fortunately, collisions should be rather unlikely.

Sgr A* rips stars apart quite easily and with great fervor; over an entire stellar diameter, these tidal effects become very significant, although the star still has to come within the Roche limit to be seriously affected. The thing is, the outer layers of a star tend not to be held very strongly; they really do fly off with slight provocation. Full-on stellar collisions are extremely rare (there'll be maybe two-five in the entire Milkomeda merger), and hardly ever result in GRBs; instead, they tend to form a single, more massive star.

[Kuroneko]

For most mergers, this is in fact correct. AGN are very rare nowadays, and even quasars and such eventually exhaust their fuel. The movies I've seen produced by the astronomy department here (here's one) show that really, not much happens on a small scale.

Neat. Thank you.

Sgr A* rips stars apart quite easily and with great fervor; over an entire stellar diameter, these tidal effects become very significant, although the star still has to come within the Roche limit to be seriously affected. The thing is, the outer layers of a star tend not to be held very strongly; they really do fly off with slight provocation. Full-on stellar collisions are extremely rare (there'll be maybe two-five in the entire Milkomeda merger), and hardly ever result in GRBs; instead, they tend to form a single, more massive star.

Well, sure--even an order of magnitude of 1E-4 g per meter adds up to a lot for a stellar diameter, enough to greatly affect stellar cohesiveness. By "without much violence", I mean that the radius of curvature is high enough to to keep the tidal forces low, which should in turn keep the frictional heating likewise low, at least compared to the GRB-scale events.

[Posner]

http://www.youtube.com/watch?v=jexMl2SO6_I

It's a simulation of the Andromeda/Milky Way collision. I am not sure where I got the link, I hope I am not just worthlessly reposting it here, but it is a very mesmerizing little video.