APOD: A February without Sunspots (2019 Mar 06)

[Chris Peterson]

True. But over the five billion years that the sun has been around, even a very very slight self interaction would equilibrate the concentration.

Maybe... depending on the kind of interaction. If it's gravity alone, the result could be dilution, as well, like the way that globular clusters evaporate. The transfer of orbital angular momentum concentrates some mass, but also scatters some. So any concentration may be paired with an overall mass reduction.

[BDanielMayfield]

True. But over the five billion years that the sun has been around, even a very very slight self interaction would equilibrate the concentration.

What do you mean by this?

I used to wonder about how much of the Sun's mass, the Earth's mass, etc. might be dark matter, but Chris' logical points about momentum put my mind at ease about these questions.

If a significant amount of the mass internal to stars is dark matter it throws off the equations of state re the conditions inside stars and therefore stellar lifetimes. Simply stated, stars can't run on dark matter, so if their cores aren't fully normal matter they couldn't last as long as they are observed to be doing universally.

Bruce