![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||
|
![]() | It is requested that a photograph be
included in this article to
improve its quality.
The external tool WordPress Openverse may be able to locate suitable images on Flickr and other web sites. |
![]() | It is requested that a map or maps be
included in this article to
improve its quality. Wikipedians in astronomy may be able to help! |
It's odd with these large M-type asteroids in that they seem to have densities far below anything expected of solid metallic bodies. (I'm thinking of two particular examples 22 Kalliope and 16 Psyche). They have densities of 2.4 and ~2 g/cm³ which, if they are made of Ni-Fe metal, indicates a huge porosity of about 70% or more! That's more porous than plausible! This is discussed in e.g. D.T. Britt et al, Asteroids III, p. 485. Off the top of my head possible but completely unchecked explanations would be e.g.
These are just suppositions, though. Does anyone have any fresh data, references, or analysis of this issue? Michaelbusch? Deuar 21:18, 9 May 2006 (UTC)
Current scientific consensus, or at least as close as there is to consensus, is that different compositions can give the M-type spectral class. Objects that are spectrally the same show very different radar albedos. There really is no 'metallic spectrum' in the visible and near-IR. Rather, metallics and many other things are featureless except for a spectral slope towards the red. Note: 16 Psyche is metallic. Its density is estimated at ~3.5 g/cm^3. Michaelbusch 22:41, 9 May 2006 (UTC)
Added a section on bulk density and porosity and provided a table with the most current estimates for the notable M-type asteroids and a few others. Also included a brief discussion about how this is used to infer composition and possible internal structures. RunningNonsenseMan ( talk) 16:22, 29 December 2021 (UTC)
The asteroid page needs pictures, I simply can't find any pictures on the internet of M-type asteroids and if this had one everyone would be ever so pleased —Preceding unsigned comment added by Visiting Guest ( talk • contribs) 17:15, 12 September 2008 (UTC)
Added the picture of Lutetia from Rosetta (the only M-type yet visited by spacecraft). Also added a number of images illustrating the possible compositions of the M-type asteroids. RunningNonsenseMan ( talk) 16:22, 29 December 2021 (UTC)
This article lacks a real definition.
"partially known composition; they are moderately bright..."
This is no definition. Is M for metal? Are they metal asteroids, or what? OlavN ( talk) 09:40, 4 February 2010 (UTC)
Also, why isn't this page linked to the asteroids page, there is no mention of m-type classification on that page directly —Preceding unsigned comment added by 24.141.23.84 ( talk) 03:15, 6 February 2010 (UTC)
I want to make the same comment. I was reading a page about 16 Psyche and it was referred to as an M-type asteroid. Not knowing what that was I clicked the link to learn that "M-type asteroids are asteroids of partially known composition; they are moderately bright (albedo 0.1–0.2)." I thought "WTF? It just means they're moderately bright and partially known?" Misleading, to say the least. — Preceding unsigned comment added by 121.98.218.165 ( talk) 07:05, 16 July 2011 (UTC) The article needs to say if M-type asteroids come from a specific orbit or not. ¿Do they belong to a main planet lagrange point? the main asteroid belt? unknown places? — Preceding unsigned comment added by 186.59.90.135 ( talk) 14:28, 5 January 2014 (UTC)
I am very familiar with this class of asteroids and made some changes to the definition and current thinking. RunningNonsenseMan ( talk) 18:43, 22 December 2021 (UTC)
I edited the redlink to redirect to the page called Asteroid spectral types. If the reader wants to know about 'reflectance spectr[a]', they will have to make a page for that! Like the previous three commentors have noted, it is difficult for a layman to understand this definition. Thus, further explanation is needed- or at least a note at the beginning of the article explaining why M is NOT for metal. — Preceding unsigned comment added by 98.234.49.111 ( talk) 01:29, 11 March 2012 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||
|
![]() | It is requested that a photograph be
included in this article to
improve its quality.
The external tool WordPress Openverse may be able to locate suitable images on Flickr and other web sites. |
![]() | It is requested that a map or maps be
included in this article to
improve its quality. Wikipedians in astronomy may be able to help! |
It's odd with these large M-type asteroids in that they seem to have densities far below anything expected of solid metallic bodies. (I'm thinking of two particular examples 22 Kalliope and 16 Psyche). They have densities of 2.4 and ~2 g/cm³ which, if they are made of Ni-Fe metal, indicates a huge porosity of about 70% or more! That's more porous than plausible! This is discussed in e.g. D.T. Britt et al, Asteroids III, p. 485. Off the top of my head possible but completely unchecked explanations would be e.g.
These are just suppositions, though. Does anyone have any fresh data, references, or analysis of this issue? Michaelbusch? Deuar 21:18, 9 May 2006 (UTC)
Current scientific consensus, or at least as close as there is to consensus, is that different compositions can give the M-type spectral class. Objects that are spectrally the same show very different radar albedos. There really is no 'metallic spectrum' in the visible and near-IR. Rather, metallics and many other things are featureless except for a spectral slope towards the red. Note: 16 Psyche is metallic. Its density is estimated at ~3.5 g/cm^3. Michaelbusch 22:41, 9 May 2006 (UTC)
Added a section on bulk density and porosity and provided a table with the most current estimates for the notable M-type asteroids and a few others. Also included a brief discussion about how this is used to infer composition and possible internal structures. RunningNonsenseMan ( talk) 16:22, 29 December 2021 (UTC)
The asteroid page needs pictures, I simply can't find any pictures on the internet of M-type asteroids and if this had one everyone would be ever so pleased —Preceding unsigned comment added by Visiting Guest ( talk • contribs) 17:15, 12 September 2008 (UTC)
Added the picture of Lutetia from Rosetta (the only M-type yet visited by spacecraft). Also added a number of images illustrating the possible compositions of the M-type asteroids. RunningNonsenseMan ( talk) 16:22, 29 December 2021 (UTC)
This article lacks a real definition.
"partially known composition; they are moderately bright..."
This is no definition. Is M for metal? Are they metal asteroids, or what? OlavN ( talk) 09:40, 4 February 2010 (UTC)
Also, why isn't this page linked to the asteroids page, there is no mention of m-type classification on that page directly —Preceding unsigned comment added by 24.141.23.84 ( talk) 03:15, 6 February 2010 (UTC)
I want to make the same comment. I was reading a page about 16 Psyche and it was referred to as an M-type asteroid. Not knowing what that was I clicked the link to learn that "M-type asteroids are asteroids of partially known composition; they are moderately bright (albedo 0.1–0.2)." I thought "WTF? It just means they're moderately bright and partially known?" Misleading, to say the least. — Preceding unsigned comment added by 121.98.218.165 ( talk) 07:05, 16 July 2011 (UTC) The article needs to say if M-type asteroids come from a specific orbit or not. ¿Do they belong to a main planet lagrange point? the main asteroid belt? unknown places? — Preceding unsigned comment added by 186.59.90.135 ( talk) 14:28, 5 January 2014 (UTC)
I am very familiar with this class of asteroids and made some changes to the definition and current thinking. RunningNonsenseMan ( talk) 18:43, 22 December 2021 (UTC)
I edited the redlink to redirect to the page called Asteroid spectral types. If the reader wants to know about 'reflectance spectr[a]', they will have to make a page for that! Like the previous three commentors have noted, it is difficult for a layman to understand this definition. Thus, further explanation is needed- or at least a note at the beginning of the article explaining why M is NOT for metal. — Preceding unsigned comment added by 98.234.49.111 ( talk) 01:29, 11 March 2012 (UTC)