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

Comments and questions about the APOD on the main view screen.
BDanielMayfield
Don't bring me down
Posts: 2524
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

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" :!:
Just as zero is not equal to infinity, everything coming from nothing is illogical.

User avatar
Chris Peterson
Abominable Snowman
Posts: 18573
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA
Contact:

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

*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com

User avatar
geckzilla
Ocular Digitator
Posts: 9180
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA
Contact:

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
Don't bring me down
Posts: 2524
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

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.
Just as zero is not equal to infinity, everything coming from nothing is illogical.

Post Reply