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

Comments and questions about the APOD on the main view screen.
BDanielMayfield
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Re: APOD: Arp 87: Merging Galaxies from Hubble (2019 Aug 11)

Post by BDanielMayfield » Mon Aug 12, 2019 7:28 pm

Chris Peterson wrote:
Mon Aug 12, 2019 5:44 pm
BDanielMayfield wrote:
Mon Aug 12, 2019 5:35 pm
Chris Peterson wrote:
Mon Aug 12, 2019 2:43 pm


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" :!:
"Happy are the peaceable ... "

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

Post by Chris Peterson » Mon Aug 12, 2019 7:45 pm

BDanielMayfield wrote:
Mon Aug 12, 2019 7:28 pm
Chris Peterson wrote:
Mon Aug 12, 2019 5:44 pm
BDanielMayfield wrote:
Mon Aug 12, 2019 5:35 pm


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.
Chris

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

Post by geckzilla » Tue Aug 13, 2019 6:14 am

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.
Just call me "geck" because "zilla" is like a last name.

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

Post by BDanielMayfield » Tue Aug 13, 2019 6:38 am

geckzilla wrote:
Tue Aug 13, 2019 6:14 am
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.
"Happy are the peaceable ... "