Talk:Accretion (astrophysics)

New article can be linked

You may be able to link to Sołtan argument at this article. 24.199.92.132 (talk) 08:28, 28 September 2008 (UTC)

No. Linking from Accretion disc would be better because Sołtan argument seems to regard the central accretion disk of the galaxies. This article seems to regard terminology, it's a border case between pure physics (as used in astronomy) and linguistics. But a natural link Accretion disc, requires some knowledge that I don't have. Please, You do it! (There's nothing like territories on wikipedia, be bold!!) I'll add a link from Accretion disc to Sołtan argument in the see also part, but it might not survive long if the connection is unclear to the maintainers of that page. Said: Rursus (☻) 09:17, 24 October 2008 (UTC)

Example was unclear

The example before my revision was unclear on whether it was talking about accretion discs around the solar system's past Jovian protoplanets, or around current extrasolar Jovian protoplanets. Since accretion discs have not been detected around extrasolar Jovian protoplanets, I presumed it meant the former and reworded it as such. Mathwhiz90601 (talk) 01:20, 28 January 2010 (UTC)

Does the accretion concept in astrophysics apply to asteroids?

There is no mention of asteroid accretion, or of small body (meteoroid, minor planets, etc.) more generally, in the article. Yet I believe the concept is used there too. A quick google search yielded:

• [1], pdf
• [2], pdf
• Growth of asteroids, planetary embryos, and Kuiper belt objects by chondrule accretion
• [3], pdf

It seems the article is missing the coverage of this aspect of accretion. Cheers. N2e (talk) 20:16, 1 December 2015 (UTC)

Yes. Accretion of galaxies, stars, planets, etc. Work in progress. By the way, I see many references use the spelling "disc" while many others use "disk". I will use "disc" throughout this article and I will leave the final decision to someone else. Cheers, BatteryIncluded (talk) 17:33, 8 January 2016 (UTC)

Nice work, I've found a couple of review articles discussing ways around the 'meter-sized barrier' by first concentrating the small particles between eddies in a turbulent disc or in pressure bumps, and the streaming instability where interactions between the gas and particles leads to the particles concentrating in each others wakes. The multifaceted planetesimal formation process, New Paradigms For Asteroid Formation Agmartin (talk) 20:37, 7 March 2016 (UTC)

Disc vs Disk (An ad hoc solution)

I only just noticed that this has been changed back and forth several times. The most stable way to quickly check the preferred spelling is to see whether or not Protoplanetary disc and Accretion disc are redirects to Protoplanetary disk and Accretion disk, or vice versa, since these are the only Wikipedia articles that need to make this discktinction in Accretion (astrophysics), and that creating the undesired redirect (whichever it may be) is a non-trivial task. Currently, discs redirect to disks.   ~ Tom.Reding (talk ⋅dgaf)  21:54, 9 January 2016 (UTC)

of/by

The title phrasing using "of" makes it sound like the galaxies and stars are being accreted by something bigger. Normally people would use the phrasing "by" or "onto" to show that these are the things that are growing. For example, gas is accreted by initially low mass protostars allowing them to grow into more massive stars. Redberryash (talk) 11:59, 18 January 2016 (UTC)

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Restructuring / different approach?

Hi, I notice most of this wiki is structured around the end results of different accretion processes (stars, planets etc.) However, there is at least one other way to look at it, based on a different question, that can lead readers here: "What happens when different kinds of (more or less) lose matter falls in on different kinds of astronomical bodies?" To illustrate, I myself came because I was wondering about the process of a neutron star "swallowing" a planet in a fly-by.--Cancun771 (talk) 04:38, 9 July 2018 (UTC)

Accretion: Dust has no gravity. How do clumps of dust therefore clump together to ultimately create planets?

First thing: I am not a scientist. I do not understand much of scientific answers. I am just an average Joe out here, curious about the formation of the Planets.

I understand this word 'Accretion' somewhat.

Here is my question. The Big Bang theory (from nothing comes something), tells me that there are just dust particles floating around in space. To my knowledge, dust has no gravitational pull, therefore, dust cannot begin to clump together to form larger particles. IF dust cannnot clump together, it seems impossible that dust could be banging together in space to create larger clumps that continually bang together, to ultimately create planets.

Maybe someone can help me out here in average IQ (C-student) language.

Beaconboy (talk) 03:00, 11 October 2019 (UTC)

If the dust and gas are not distributed evenly on large scales the denser regions will shrink due to the gravity of the entire mass eventually forming stars. At smaller scales dust and gas orbiting a star form into a rotating disk. At very small sizes there is [Brownian motion] to bring the dust particles together. At larger sizes turbulence in the gas will bring dust together. Small enough dust will stick together like dust bunnies, once the grains gets bigger they get denser and start to bounce instead of stick. A popular idea these day among the people studying this is when a bunch of the larger grains are close together they draft like a group of bicycles and are joined by more until there is enough for their gravity to collapse them and form asteroids. Agmartin (talk) 21:34, 11 October 2019 (UTC)

Incorporate New Horizons findings

The New Horizons research team has published a series of articles that they claim revise our understanding of planetary accretion. This is based on the findings of the New Horizons space probe, in particular the flyby of Arrokoth. As a non-expert, I can't comment on exactly what that means, or on how far we are from a consensus. But it seems to be a glaring omission that the only mention in this article is what looks like a rather outdated diagram of Arrokoth, pasted into the Comets section which seems totally out of place. I would expect a brief summary of the new results in the article about the formation of the solar system, and quite a bit of detail here. Can someone please fix that? StormWillLaugh (talk) 13:02, 2 March 2020 (UTC)