Tuesday, December 18, 2012

1212.4058 (Philip C. Gregory)

Evidence for Multiple Planets in the Habitable Zone of Gliese 667C: A Bayesian Re-analysis of the HARPS data    [PDF]

Philip C. Gregory
A re-analysis of Gliese 667C HARPS precision radial velocity data was carried out with a Bayesian multi-planet Kepler periodogram (from 0 to 7 planets) based on a fusion Markov chain Monte Carlo algorithm. The most probable number of Keplerian signals detected is 6 with a Bayesian false alarm probability of 0.012. The residuals of the 6 planet model are shown to be consistent with white noise. The 6 Keplerian signals detected include two previously reported with periods of 7.198 (b) and 28.14 (c) days, plus additional periods of 30.82 (d), 38.82 (e), 53.22, and 91.3 (f) days. The 53 day signal is probably the second harmonic of the stellar rotation period and is likely the result of surface activity. Assuming the other five signals are planetary in origin, the 28.14, 30.82 and 38.82 day orbits are all in the central portion of the habitable zone while the 91.3 day orbit lies partly within the habitable zone. The M sin i values for planets b, c, d, e, and f are ~ 5.4, 4.8, 3.1, 2.4, and 5.4 times the mass of the Earth, respectively. If confirmed by further observations, planet e (38.82 day period) is the lowest mass planet in the habitable zone detected to date.
View original: http://arxiv.org/abs/1212.4058

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