Tuesday, September 23, 2008

New Extra-Solar Planets Discovered?

In a publication put up as a pre-print today, astronomers announced they had discovered two Jupiter like planets around an F-type star which as at least two planets in its solar system, one at 1 Jupiter mass and one at 2.5 Jupiter masses. An F-type star is a bit larger and more energetic than our sun (a "G" type star) that is yellow-white in color and less energetic than the bigger "A" type stars. Astronomers remember the rather arbitrary star classification according to the moniker "Oh Be a Fine Girl and Kiss Me", or OBAFGAKM. So O stars are the biggest (blue) hottest stars, G stars like the sun are in the middle and yellow, and M stars are the smallest and least energetic (and hence red). So an F-type star is slightly larger, more energetic, and whiter than our own sun.

The abstract of this paper reads thus:

Extrasolar planets and brown dwarfs around A-F type stars V. A planetary system found with HARPS around the F6IV-V star HD 60532

Aims: In the frame of the search for extrasolar planets and brown dwarfs around early-type stars, we present the results obtained for the F-type main-sequence star HD 60532 (F6V) with HARPS.
Methods: Using 147 spectra obtained with HARPS at La Silla on a time baseline of two years, we study the radial velocities of this star.
Results: HD 60532 radial velocities are periodically variable, and the variations have a Keplerian origin. This star is surrounded by a planetary system of two planets with minimum masses of 1 and 2.5 Mjup and orbital separations of 0.76 and 1.58 AU respectively. We also detect high-frequency, low-amplitude (10 m/s peak-to-peak) pulsations. Dynamical studies of the system point toward a possible 3:1 mean-motion resonance which should be confirmed within the next decade.

You can download the original paper here:

Extra-Solar Planets

No comments: