Two Exoplanets Discovered at Keck Observatory

Creators: Valenti, Jeff A.; Fischer, Debra; Marcy, Geoffrey W.; Johnson, John A.; Henry, Gregory W.; Wright, Jason T.; Howard, Andrew W.; Giguere, Matt; Isaacson, Howard

Abstract

We present two exoplanets detected at Keck Observatory. HD 179079 is a G5 subgiant that hosts a hot Neptune planet with M sin i = 27.5 M_⊕ in a 14.48 days, low-eccentricity orbit. The stellar reflex velocity induced by this planet has a semiamplitude of K = 6.6 m s^(–1). HD 73534 is a G5 subgiant with a Jupiter-like planet of M sin i = 1.1 M_(Jup) and K = 16 m s^(–1) in a nearly circular 4.85 yr orbit. Both stars are chromospherically inactive and metal-rich. We discuss a known, classical bias in measuring eccentricities for orbits with velocity semiamplitudes, K, comparable to the radial velocity uncertainties. For exoplanets with periods longer than 10 days, the observed exoplanet eccentricity distribution is nearly flat for large amplitude systems (K > 80 m s^(–1)), but rises linearly toward low eccentricity for lower amplitude systems (K > 20 m s^(–1)).

Additional Information

© 2009 American Astronomical Society. Received 2008 December 21; accepted 2009 July 7; published 2009 August 18. Based on observations obtained at the Keck Observatory, which is operated by the University of California. We gratefully acknowledge the dedication and support of the Keck Observatory staff, in particular Grant Hill for support with HIRES. D.A.F. acknowledges research support from NASA grant NNX08AF42G. G.W.H. acknowledges support from NASA, NSF, Tennessee State University, and the State of Tennessee through its Centers of Excellence program. We thank the NASA Exoplanet Science Institute (NExScI) for support through the KPDA program. We thank the NASA and NOAOTelescope assignment committees for allocations of telescope time. The authors extend thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their kind hospitality, the Keck observations presented here would not have been possible. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France, and of NASA's Astrophysics Data System Bibliographic Services.

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