Re: Why Would Aliens Hide?

Robin Hanson (
Wed, 24 Nov 1999 16:35:45 -0500

Amara Graps wrote:
>... every once in a while I bump
>into research where there seems to be some open questions about
>whether stars can really produce all of the dust that we observe. In
>a talk that I heard today at my institute, the conclusion was that
>stars cannot produce all of the dust that we see in galactic disks.
>... star formation is depleting the interstellar medium (ISM) gas
>by some 3 to 10 solar masses per year. ... Supernovae shock waves
>... destroying 0.1-0.3 solar masses per year in dust. ...
>0.01-0.08 solar masses per year of dust is returned to the ISM by
>stars. He feels that grain growth in dark clouds is an attractive
>mechanism to make up the dust deficit.

Interesting. Unexplained excess of dust production seems the opposite of what one would expect from aliens greedily eating up all the metals they can find.

Robin Hanson Asst. Prof. Economics, George Mason University MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323