Guillem Anglada-Escudé, Pamela Arriagada, Steven S. Vogt, Eugenio J. Rivera, R. Paul Butler, Jeffrey D. Crane, Stephen A. Shectman, Ian B. Thompson, Dante Minniti, Nader Haghighipour, Brad D. Carter, C. G. Tinney, Robert A. Wittenmyer, Jeremy A. Bailey, Simon J. O'Toole, Hugh R. A. Jones, James S. Jenkins
We re-analyze 4 years of HARPS spectra of the nearby M1.5 dwarf GJ 667C
available through the ESO public archive. The new radial velocity (RV)
measurements were obtained using a new data analysis technique that derives the
Doppler measurement and other instrumental effects using a least-squares
approach. Combining these new 143 measurements with 41 additional RVs from the
Magellan/PFS and Keck/HIRES spectrometers, reveals 3 additional signals beyond
the previously reported 7.2-day candidate, with periods of 28 days, 75 days,
and a secular trend consistent with the presence of a gas giant (Period sim 10
years). The 28-day signal implies a planet candidate with a minimum mass of 4.5
Mearth orbiting well within the canonical definition of the star's liquid water
habitable zone, this is, the region around the star at which an Earth-like
planet could sustain liquid water on its surface. Still, the ultimate water
supporting capability of this candidate depends on properties that are unknown
such as its albedo, atmospheric composition and interior dynamics. The 75-day
signal is less certain, being significantly affected by aliasing interactions
among a potential 91-day signal, and the likely rotation period of the star at
105 days detected in two activity indices. GJ 667C is the common proper motion
companion to the GJ 667AB binary, which is metal poor compared to the Sun. The
presence of a super-Earth in the habitable zone of a metal poor M dwarf in a
triple star system, supports the evidence that such worlds should be ubiquitous
in the Galaxy.
View original:
http://arxiv.org/abs/1202.0446
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