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Published February 1, 2010 | Published
Journal Article Open

Refined stellar, orbital and planetary parameters of the eccentric HAT-P-2 planetary system


We present refined parameters for the extrasolar planetary system HAT-P-2 (also known as HD 147506), based on new radial velocity and photometric data. HAT-P-2b is a transiting extrasolar planet that exhibits an eccentric orbit. We present a detailed analysis of the planetary and stellar parameters, yielding consistent results for the mass and radius of the star, better constraints on the orbital eccentricity and refined planetary parameters. The improved parameters for the host star are M_★= 1.36 ± 0.04 M_⊙ and R_★= 1.64 ± 0.08 R_⊙, while the planet has a mass of M_p= 9.09 ± 0.24 M_Jup and radius of R_p= 1.16 ± 0.08 R_Jup. The refined transit epoch and period for the planet are E= 245 4387.49375 ± 0.00074 (BJD) and P= 5.6334729 ± 0.0000061 (d), and the orbital eccentricity and argument of periastron are e= 0.5171 ± 0.0033 and ω= 185°.22 ± 0°.95. These orbital elements allow us to predict the timings of secondary eclipses with a reasonable accuracy of ∼15 min. We also discuss the effects of this significant eccentricity including the characterization of the asymmetry in the transit light curve. Simple formulae are presented for the above, and these, in turn, can be used to constrain the orbital eccentricity using purely photometric data. These will be particularly useful for very high precision, space-borne observations of transiting planets.

Additional Information

© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 October 8. Received 2009 October 7; in original form 2009 August 12. The work by AP was supported by the HATNet project and in part by ESA grant PECS 98073. HATNet operations have been funded by NASA grants NNG04GN74G, NNX08AF23G and SAO IR&D grants. Work of GÁB and JAJ were supported by the Post-doctoral Fellowship of the NSF Astronomy and Astrophysics Program (AST-0702843 and AST-0702821, respectively). GT received partial support from NASA Origins grant NNX09AF59G. We acknowledge partial support also from the Kepler Mission under NASA Cooperative Agreement NCC2-1390 (DWL, PI). This research has made use of Keck telescope time granted through NOAO and NASA. We thank the UCO/Lick technical staff for supporting the remote observing capability of the Nickel Telescope, allowing the photometry to be carried out from UC Berkeley. Automated Astronomy at Tennessee State University has been supported long term by NASA and NSF as well as Tennessee State University and the State of Tennessee through its Centers of Excellence program. We are grateful for the comments and suggestions by the referee, Frederic Pont.We acknowledge the use of the VizieR service (Ochsenbein, Bauer & Marcout 2000) operated at CDS, Strasbourg, France, of NASA's Astrophysics Data System Abstract Service, and of the 2MASS Catalogue.

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Published - j.1365-2966.2009.15849.x.pdf


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