Multiple, Multiple Exo-planets...

Nicolaus Copernicus wrote "On the Revolutions of the Celestial Spheres," first forwarding the hypothesis of a heliocentric not geocentric solar system, challenging the viewpoint promoted by dogma up to that time. He published his views just before his death.

Galileo Galilei peered into the night sky with his improved telescope and changed us conclusively from a earth-centered worldview to a heliocentric worldview. It's now taken for granted that the earth orbits around the sun. Centuries ago, such talk was heresy and deserving of isolation or worse. (Maybe Copernicus was more prudent and knew his audience?)

"A new study published in tomorrow's issue of Science estimates that in the coming months, the spacecraft, called Kepler, should find a few hundred Earth-sized exoplanets orbiting uncomfortably close to their stars. As many or more should turn up in the next year or two, farther from their stars where life could thrive."

The article is at the AAAS web site: No Lack of Exo-Earths Out There.

The abstract is available. To read the full paper, you would have to either subscribe to Science or be a member of AAAS.

The abstract follows:

The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters

Andrew W. Howard,1,2,* Geoffrey W. Marcy,1 John Asher Johnson,3 Debra A. Fischer,4 Jason T. Wright,5 Howard Isaacson,1 Jeff A. Valenti,6 Jay Anderson,6 Doug N. C. Lin,7,8 Shigeru Ida9

The questions of how planets form and how common Earth-like planets are can be addressed by measuring the distribution of exoplanet masses and orbital periods. We report the occurrence rate of close-in planets (with orbital periods less than 50 days), based on precise Doppler measurements of 166 Sun-like stars. We measured increasing planet occurrence with decreasing planet mass (M). Extrapolation of a power-law mass distribution fitted to our measurements, df/dlogM = 0.39 M–0.48, predicts that 23% of stars harbor a close-in Earth-mass planet (ranging from 0.5 to 2.0 Earth masses). Theoretical models of planet formation predict a deficit of planets in the domain from 5 to 30 Earth masses and with orbital periods less than 50 days. This region of parameter space is in fact well populated, implying that such models need substantial revision.

1 Department of Astronomy, University of California, Berkeley, CA 94720, USA.
2 Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA.
3 Department of Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA.
4 Department of Astronomy, Yale University, New Haven, CT 06511, USA.
5 Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA.
6 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA.
7 University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064, USA.
8 Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, China.
9 Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan.

* To whom correspondence should be addressed. E-mail: howard@astro.berkeley.edu