Dust or Suns: Which Contributes More to Dark Matter in Space?

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Discussion Overview

The discussion revolves around the contributions of interstellar dust and stars to the overall composition of dark matter in space, particularly in the context of galaxies and galaxy clusters. Participants explore definitions, ratios, and the origins of these materials, engaging in a mix of conceptual and technical reasoning.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that intergalactic dust contributes significantly to the mass in galaxy clusters, suggesting a ratio of mass between stars, dust, and dark matter.
  • Others argue that the terminology around "dust" is often confused, clarifying that in astrophysics, "dust" refers to elements heavier than helium, while most baryonic mass is in gas.
  • A participant suggests a breakdown of mass in a large galactic cluster as approximately 80% dark matter, 18% gas, 1% dust, and 1% stars, but acknowledges uncertainty in exact figures.
  • Another participant questions whether the Big Bang theory accounts for the formation of dust, noting that heavier elements are formed in stars and supernovae.
  • One participant shares data on the elemental composition of the interstellar medium, indicating a predominance of hydrogen and helium, with a small percentage of heavier elements.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and contributions of dust and stars to dark matter, with no consensus reached on specific ratios or the implications of these materials in the context of dark matter.

Contextual Notes

There are limitations in the discussion regarding the definitions of "dust" and "gas," as well as the uncertainty in the ratios of mass contributions from stars, dust, and dark matter. The breakdowns provided are based on approximations and may vary in different contexts.

ClamShell
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I guess dark matter is the most abundant
matter. But which contributes next to the
most, intersteller dust or suns?
 
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ClamShell said:
I guess dark matter is the most abundant
matter. But which contributes next to the
most, intersteller dust or suns?
Mostly intergalactic dust, actually. This is especially the case for galaxy clusters, where there is something like ten times as much mass in the cluster gas as there is in stars.

I'm not entirely sure what the breakdown is for individual galaxies outside of clusters, though.
 
Chalnoth said:
Mostly intergalactic dust, actually. This is especially the case for galaxy clusters, where there is something like ten times as much mass in the cluster gas as there is in stars.

I'm not entirely sure what the breakdown is for individual galaxies outside of clusters, though.

Does anyone have a current value for the ratios?

Say for every gram of stars there might be 3 grams
of dust and 10 grams of dark matter(mass?)

IE, 1 : 3 : 10
 
I think you're confusing the terminology. In astrophysics parlance, "dust" refers to elements heavier than helium. Most of the baryon mass of a galaxy or a cluster is in interstellar or intergalactic gas, not dust. I don't have exact figures, but I think for a large galactic cluster, the numbers are roughly dark matter about 80%, baryons about 20%, and the baryons break down about 95% gas, 2% dust and 2% stars, so the total would be about 80% dark matter, 18% gas, 1% dust and 1% stars.
 
phyzguy said:
I think you're confusing the terminology. In astrophysics parlance, "dust" refers to elements heavier than helium. Most of the baryon mass of a galaxy or a cluster is in interstellar or intergalactic gas, not dust. I don't have exact figures, but I think for a large galactic cluster, the numbers are roughly dark matter about 80%, baryons about 20%, and the baryons break down about 95% gas, 2% dust and 2% stars, so the total would be about 80% dark matter, 18% gas, 1% dust and 1% stars.

Arrrggghhh, I just learned something; gas(H & He) is not dust;
should have known. The "dust" is the stuff we are made of.
(mainly C, H, O, N, P, Fe & S...)
I assume that where there is dust, there must have been a
supernova since "dust" seems to have been created inside
stars. Is the "dust" everywhere?
 
The supernovae seem to stir things up pretty good, so the data says the elemental abundances are pretty uniform. Attached is a good paper on this. In the solar neighborhood, this paper says that the interstellar medium is 71.5% H, 27.1% He, and 1.4% everything else, with O and C being the most abundant elements heavier then He.
 

Attachments

phyzguy said:
The supernovae seem to stir things up pretty good, so the data says the elemental abundances are pretty uniform. Attached is a good paper on this. In the solar neighborhood, this paper says that the interstellar medium is 71.5% H, 27.1% He, and 1.4% everything else, with O and C being the most abundant elements heavier then He.

Does the big bang theory account for any of the dust?
 
ClamShell said:
Does the big bang theory account for any of the dust?

The Big Bang formed hydrogen, helium and a tiny amount of Lithium. The rest of the chemical elements formed by nuclear fusion processes in stars and the very heavy elements formed in supernovae.
 

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