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What is the Mass of α Cen B b?

Plavchan, Peter and Chen, Xi and Pohl, Garrett (2015) What is the Mass of α Cen B b? Astrophysical Journal, 805 (2). Art. No. 174. ISSN 0004-637X.

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We investigate the possibility of constraining the sin i degeneracy of α Cen B b—with orbital period P = 3.24 days; a = 0.042 AU; m sin i = 1.1 M_⊕—to estimate the true mass of the newly reported terrestrial exoplanet in the nearest stellar system to our Sun. We present detailed numerical simulations of the dynamical stability of the exoplanet in the α Cen AB binary system for a range of initial inclinations, eccentricities, and semimajor axes. The system represents a benchmark case for the interplay of the Kozai mechanism with general relativistic and tidal forces. From our simulations, there is only a small boundary in initial inclinations and initial semimajor axes which result in the migration via the Kozai mechanism of α Cen B b to its present location. Inside this boundary, the planet orbit is stable for up to 1 Gyr against the Kozai mechanism, and outside this boundary the planet collides with α Cen B or is ejected. In our three simulations where the planet migrates in toward the star via the Kozai mechanism, the final inclination is 46°–53° relative to the AB orbital plane, lower than the initial inclination of 75° in each case. We discuss inclination constraints from the formation of α Cen B b in situ at its present location, migration in a proto-planetary disk, or migration in resonance with additional planets. We conclude that α Cen B b probably has a mass of less than 2.7 M_⊕, implying a likely terrestrial composition warranting future confirmation.

Item Type:Article
Related URLs:
URLURL TypeDescription
Plavchan, Peter0000-0002-8864-1667
Chen, Xi0000-0001-9152-6224
Alternate Title:What is the Mass of alpha Cen B beta?
Additional Information:© 2015 The American Astronomical Society. Received 2014 November 5; accepted 2015 March 27; published 2015 June 2. We thank the anonymous referee for a thoughtful review that improved the clarity and presentation of this manuscript. The authors acknowledge Thayne Currie, Dave Latham, and David Ciardi for their encouragement in writing this paper. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. P.P. acknowledges support from a NASA JPL Research and Technology Development program, and the Missouri SpaceGrant Consortium.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
JPL Research and Technology Development FundUNSPECIFIED
Missouri SpaceGrant ConsortiumUNSPECIFIED
Subject Keywords:planets and satellites: dynamical evolution and stability; planets and satellites: formation; planets and satellites: individual (α Centauri)
Issue or Number:2
Record Number:CaltechAUTHORS:20150720-100927750
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Official Citation:What is the Mass of α Cen B b? Peter Plavchan et al. 2015 ApJ 805 174
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58941
Deposited By: Jason Perez
Deposited On:20 Jul 2015 20:50
Last Modified:03 Oct 2019 08:41

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