Talk:Galactic halo

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This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Sdrury164. Peer reviewers: Kirdem.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 22:00, 16 January 2022 (UTC)

Galactic disc

Is the galactic disc all on a plane? Is the galactic bulge not part of the disc? Gerry Lynch 11:16, 4 Aug 2004 (UTC)

Yes, galactic discs are usually pretty thin and planar, although they are often warped - in the Milky Way, the disk is about 15 kpc in radius but much less than 1 kpc thick. And the galactic bulge is not really part of the galactic disc - it has a completely different stellar population for a start, although similar in many respects to the halo - indeed, the bulge is sometimes thought to be a dense inner part of the halo. But the bulge includes a significant quantity of the stars in a spiral galaxy, so I've added a line about it. -- ALoan (Talk) 13:24, 4 Aug 2004 (UTC)

This article desperately needs some sort of image or diagram. What is the "main, visible component"? Isn't the whole thing visible? Or is that what they call the 'stellar halo'? What do they call the bulge in the middle - a 'bulge'? OsamaBinLogin (talk) 00:58, 17 February 2020 (UTC)

disambig

i've changed this to a disambig page - in the MW, the galactic spheroid is a totally negligible component from a dynamical point of view relative to the DM halo, the spheroid only constitutes about 0.1% of the total mass - so there's really a big danger in confusing the different components by calling them part of a single "halo". The only thing common to them is that they're more or less spherically symmetric (meaning that their stars/particles travel in a spatial distribution which is roughly spherically symmetric), which is where the word halo comes from, but there's no strong physical link between them.

The word corona was used by at least one galactic structure astronomer to describe the galactic spheroid during the '90s, but now it seems to have been picked up for something more closer, in physical nature, to the Sun's corona - this is relatively new stuff, so i've added a start galactic corona with 3 astro-ph links for anyone interested in reading/writing further.

1. the galactic spheroid component - stars
2. the galactic corona - some hot gas (ie. a plasma)
3. the dark matter halo

Boud 15:26, 16 March 2006 (UTC)

This seems reasonable so I've turned the page into a proper disambiguation. Sam Walton (talk) 15:31, 20 October 2015 (UTC)

Lack of Information

The way you present the galactic halo is unclear. You say "several distinct components to galaxies comprise the halo," but it would be more helpful to discuss where relative to the center of the galaxy those components are found. Also, a picture would make what you are trying to present clearer. Hmedina19 (talk) 21:17, 12 March 2017 (UTC)

@Hmedina19: Agreed. I've started a draft regarding the stellar halo here but never finished it: Draft:Stellar halo. Assistance appreciated. Sam Walton (talk) 15:33, 13 March 2017 (UTC)

Halos are illusions

Most halos we are familiar with are illusions. The halo around the moon due to clouds, Halos around a streetlight on a foggy night are some examples. They are caused by light refracted from material between the light source and the viewer not light reflected or emitted from material around the source. There should be some discussion on how we know the halo is attached to galaxies not just illusions caused by material between us and the source as most halos we are familiar with are. 98.164.67.198 (talk) 07:31, 8 December 2017 (UTC)