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The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core

Sato, Bun'ei and Fischer, Debra A. and Henry, Gregory W. and Laughlin, Greg and Butler, R. Paul and Marcy, Geoffrey W. and Vogt, Steven S. and Bodenheimer, Peter and Ida, Shigeru and Toyota, Eri and Wolf, Aaron and Valenti, Jeff A. and Boyd, Louis J. and Johnson, John A. and Wright, Jason T. and Ammons, Mark and Robinson, Sarah and Strader, Jay and McCarthy, Chris and Tah, K. L. and Minniti, Dante (2005) The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core. Astrophysical Journal, 633 (1). pp. 465-473. ISSN 0004-637X. doi:10.1086/449306.

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Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V = 8.15, G0 IV star HD 149026 consistent with a Saturn-mass planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory have detected three complete transit events with depths of 0.003 mag at the predicted times of conjunction. HD 149026 is now the second-brightest star with a transiting extrasolar planet. The mass of the star, based on interpolation of stellar evolutionary models, is 1.3 ± 0.1 M_☉; together with the Doppler amplitude K_1 = 43.3 m s^(-1), we derive a planet mass M sin i = 0.36M_J and orbital radius 0.042 AU. HD 149026 is chromospherically inactive and metal-rich with spectroscopically derived [Fe/H] = +0.36, T_(eff) = 6147 K, log g = 4.26, and v sin i = 6.0 km s^(-1). Based on T_(eff) and the stellar luminosity of 2.72 L_☉, we derive a stellar radius of 1.45 R_☉. Modeling of the three photometric transits provides an orbital inclination of 85º.3 ± 1º.0 and (including the uncertainty in the stellar radius) a planet radius of (0.725 ± 0.05)R_J. Models for this planet mass and radius suggest the presence of a ~67 M_⊕ core composed of elements heavier than hydrogen and helium. This substantial planet core would be difficult to construct by gravitational instability.

Item Type:Article
Related URLs:
URLURL TypeDescription
Fischer, Debra A.0000-0003-2221-0861
Henry, Gregory W.0000-0003-4155-8513
Laughlin, Greg0000-0002-3253-2621
Marcy, Geoffrey W.0000-0002-2909-0113
Bodenheimer, Peter0000-0001-6093-3097
Valenti, Jeff A.0000-0003-3305-6281
Johnson, John A.0000-0001-9808-7172
Wright, Jason T.0000-0001-6160-5888
Strader, Jay0000-0002-1468-9668
Minniti, Dante0000-0002-7064-099X
Additional Information:© 2005 American Astronomical Society. Receivved 2005 May 31; accepted 2005 June 28. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Based on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NOAO and NASA. We thank Akito Tajitsu for his expertise and support of the Subaru HDS observations. We gratefully acknowledge the dedication and support of the Keck Observatory staff, in particular Grant Hill for support with HIRES. We thank the NOAO and NASA telescope assignment committees for generous allocations of telescope time. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to NASA through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We thank the Michaelson Science Center for travel support through the KDPA program. D. A. F. is a Cottrell Science Scholar of the Research Corporation. We acknowledge support from NASA grant NNG05G164G (to D. A. F.), NASA grant NCC5-511 and NSF grant HRD 97-06268 (to G. W. H. ), NASA grant NAG5- 75005 (to G. W. M. ), NSF grant AST 99-88358 and NASA grant NAG5-4445 (to S. S. V.), NASA grant NAG5-13285 (to P. B.), and NASA grant NNA04CC99A (to G. L.). G.W. H. also acknowledges timely support by David Bradstreet for requested modifications to his light-curve analysis software to fit the unexpectedly shallow transits in HD 149026 and thanks Stephen Henry for assistance in the preparation of Figure 5. D.M. is supported by FONDAP 15010003. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. The authors extend thanks to those of native Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Subaru and Keck observations presented herein would not have been possible.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
NSFHRD 97-06268
NSFAST 99-88358
Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias (FONDAP)15010003
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Record Number:CaltechAUTHORS:20130110-110537594
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Official Citation:The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core Bun'ei Sato et al. 2005 ApJ 633 465
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36302
Deposited By: Ruth Sustaita
Deposited On:10 Jan 2013 19:37
Last Modified:09 Nov 2021 23:21

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