APOD: Arp 87: Merging Galaxies from Hubble (2019 Aug 11)

[BDanielMayfield]

Except that puffs of smoke don't interact with each other to create temperatures high enough to initiate nuclear fusion.

But pferkul has a good point too. When galaxies "collide" their stars, having such vast distances between them in the first place, will almost never collide. The "violence" of an event that takes a billion or more years to occur is overstated for dramatic effect.

Bruce

The "violence" I see describes the collisions of gas and dust, not stars. And the time scale seems to me irrelevant. I don't think it's unreasonable to describe as "violent" any physical process that releases a lot of energy over a relatively short period of time, regardless of the spatial scale, regardless of the temporal scale.

Ok, if we're calling a billion years "a relatively short period of time"

[Chris Peterson]

But pferkul has a good point too. When galaxies "collide" their stars, having such vast distances between them in the first place, will almost never collide. The "violence" of an event that takes a billion or more years to occur is overstated for dramatic effect.

Bruce

The "violence" I see describes the collisions of gas and dust, not stars. And the time scale seems to me irrelevant. I don't think it's unreasonable to describe as "violent" any physical process that releases a lot of energy over a relatively short period of time, regardless of the spatial scale, regardless of the temporal scale.

Ok, if we're calling a billion years "a relatively short period of time" :!:

I don't think we're talking about a billion years. These periods of collision leading to star formation are much shorter- a few hundred million years, perhaps. And yes, that is relatively short given orbital periods measured in billions of years.

[geckzilla]

Astronomers for some reason have a long history of using crappy words to describe the process of galactic interaction and merging. When I write about it myself I try to avoid harrowing anthropocentric descriptors. I describe it as a dance that leads to changes for both galaxies rather than a violent event or cannibalism (why do they call it cannibalism SO MUCH?)... anyway that's what you get when men run the show.

[BDanielMayfield]

Astronomers for some reason have a long history of using crappy words to describe the process of galactic interaction and merging. When I write about it myself I try to avoid harrowing anthropocentric descriptors. I describe it as a dance that leads to changes for both galaxies rather than a violent event or cannibalism (why do they call it cannibalism SO MUCH?)... anyway that's what you get when men run the show.

Yes. Mergers is a more apt descriptor.