The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core
Author(s) -
B. Sato,
Debra A. Fischer,
Gregory W. Henry,
G. Laughlin,
R. Paul Butler,
Geoffrey W. Marcy,
Steven S. Vogt,
Peter Bodenheimer,
Shigeru Ida,
Eri Toyota,
Aaron S. Wolf,
Jeff A. Valenti,
Louis J. Boyd,
John Asher Johnson,
Jason T. Wright,
Mark Ammons,
Sarah E. Robinson,
Jay Strader,
C. McCarthy,
K. L. Tah,
D. Minniti
Publication year - 2005
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/449306
Subject(s) - physics , planet , astrophysics , radius , astronomy , orbital inclination , exoplanet , radial velocity , planetary system , stars , binary number , computer security , arithmetic , mathematics , computer science
Doppler measurements from Subaru and Keck have revealed radial velocityvariations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Massplanet in a 2.8766 day orbit. Photometric observations at Fairborn Observatoryhave detected three complete transit events with depths of 0.003 mag at thepredicted times of conjunction. HD 149026 is now the second brightest star witha transiting extrasolar planet. The mass of the star, based on interpolation ofstellar evolutionary models, is 1.3 +/- 0.1 solar masses; together with theDoppler amplitude, K=43.3 m s^-1, we derive a planet mass Msin(i)=0.36 Mjup,and orbital radius of 0.042 AU. HD 149026 is chromospherically inactive andmetal-rich with spectroscopically derived [Fe/H]=+0.36, Teff=6147 K, log g=4.26and vsin(i)=6.0 km s^-1. Based on Teff and the stellar luminosity of 2.72 Lsun,we derive a stellar radius of 1.45 Rsun. Modeling of the three photometrictransits provides an orbital inclination of 85.3 +/- 1.0 degrees and (includingthe uncertainty in the stellar radius) a planet radius of 0.725 +/- 0.05 Rjup.Models for this planet mass and radius suggest the presence of a ~67 Mearthcore composed of elements heavier than hydrogen and helium. This substantialplanet core would be difficult to construct by gravitational instability.Comment: 25 pages, 5 figures, accepted by the Astrophysical Journa
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