A planetary system around the nearby M dwarf GJ 667C with at least one super-earth in its habitable zone

Anglada-Escude, Guillem and Arriagada, Pamela and Vogt, Steven S. and Rivera, Eugenio J. and Butler, R. Paul and Crane, Jeffrey D. and Shectman, Stephen A. and Thompson, Ian B. and Minniti, Dante and Haghighipour, Nader and Carter, Brad D. and Tinney, C. G. and Wittenmyer, Robert A. and Bailey, Jeremy A. and O'Toole, Simon J. and Jones, Hugh R. A. and Jenkins, James S. (2012) A planetary system around the nearby M dwarf GJ 667C with at least one super-earth in its habitable zone. Letters of the Astrophysical Journal, 751 (1). L16. ISSN 2041-8205

Abstract

We re-analyze 4 years of HARPS spectra of the nearby M1.5 dwarf GJ 667C available through the European Southern Observatory 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/Planet Finder Spectrograph and Keck/High Resolution Echelle Spectrometer spectrometers reveals three 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 ∼10 years). The 28 day signal implies a planet candidate with a minimum mass of 4.5M⊕ orbiting well within the canonical definition of the star’s liquid water habitable zone (HZ), that 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 HZ of a metal-poor M dwarf in a triple star system supports the evidence that such worlds should be ubiquitous in the Galaxy.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to published version due to publisher's copyright policy.
Depositing User: epEditor USQ
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 06 Oct 2012 22:43
Last Modified: 03 Jul 2013 01:14
Uncontrolled Keywords: planetary systems; stars; GJ 667C; radial velocities
Fields of Research (FOR2008): 04 Earth Sciences > 0403 Geology > 040302 Extraterrestrial Geology
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
03 Chemical Sciences > 0399 Other Chemical Sciences > 039901 Environmental Chemistry (incl. Atmospheric Chemistry)
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: doi: 10.1088/2041-8205/751/1/L16
URI: http://eprints.usq.edu.au/id/eprint/21458

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