| Subject: Re: How smart are SETI@homers? |
| From: Rich |
| Date: 19/05/2004, 17:13 |
| Newsgroups: sci.astro.seti,alt.sci.seti,sci.space.policy |
In infinite wisdom Joseph Lazio answered:
"R" == Rich <someone@somewhere.com> writes:
R> In infinite wisdom Joseph Lazio answered:
We know planets are widespread. More than 5% or 10% of
solar-type stars have Jupiter-mass planets. Serious selection
biases against finding lower-mass planets, but from the current
census it appears that there are more lower-mass planets than
Jupiter-mass planets.
R> Which census is this?
Umm, the current one? By the "current census," I mean the known
extrasolar planets.
R> Almost exclusively gas giants, only a few oddball terrestrial
R> planets. I don't see how you can derive that there are "more
R> lower-mass planets than Jupiter-mass planets" from the data at
R> hand.
From Marcy et al. (2003, "Properties of Extrasolar Planets," in
_Scientific Frontiers in Research on Extrasolar Planets_,
eds. D. Deming & S. Seager, p. 1)
The distribution of masses rises rapidly toward the lower masses,
dN/dM ~ M^{-0.7} ....
Where M is 1 jupiter mass.
Later in the paper, they point out that incompleteness for the lower
mass planets implies that the actual increase is probably even steeper
than M^{-0.7}.
Incompleteness? Implies?
Looks like supposition to me, from incomplete data no less.
Rich