The Discovery of HD 37605c and a Dispositive Null Detection of Transits of HD 37605b

Creators: Wang, Sharon Xuesong; Wright, Jason T.; Cochran, William; Kane, Stephen R.; Henry, Gregory W.; Payne, Matthew J.; Endl, Michael; MacQueen, Phillip J.; Valenti, Jeff A.; Antoci, Victoria; Dragomir, Diana; Matthews, Jaymie M.; Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Ford, Eric B.; Mahadevan, Suvrath; von Braun, Kaspar

Abstract

We report the radial velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P ~ 55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of ~7.5 years with a low eccentricity and an Msin i of ~3.4 M_(Jup). Our discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey effort to provide precise ephemerides to long-period planets for transit follow-up. With a total of 137 radial velocity observations covering almost 8 years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using the predicted ephemeris, we performed a transit search for HD 37605b with the photometric data taken by the T12 0.8 m Automatic Photoelectric Telescope (APT) and the MOST satellite. Though the APT photometry did not capture the transit window, it characterized the stellar activity of HD 37605, which is consistent of it being an old, inactive star, with a tentative rotation period of 57.67 days. The MOST photometry enabled us to report a dispositive null detection of a non-grazing transit for this planet. Within the predicted transit window, we exclude an edge-on predicted depth of 1.9% at the »10σ level, and exclude any transit with an impact parameter b > 0.951 at greater than 5σ. We present the BOOTTRAN package for calculating Keplerian orbital parameter uncertainties via bootstrapping. We made a comparison and found consistency between our orbital fit parameters calculated by the RVLIN package and error bars by BOOTTRAN with those produced by a Bayesian analysis using MCMC.

Additional Information

© 2012 American Astronomical Society. Received 2012 July 7; accepted 2012 October 23; published 2012 November 20. Based on observations obtained with the Hobby–Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen, and observations obtained at the Keck Observatory, which is operated by the University of California. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors thank John A. Johnson for providing a copy of his Doppler code and for his help with our incorporation of the code into the HET pipeline. The authors also thank Debra Fischer for her assistance in this regard. We thank Peter Plavchan, Scott Dolim, Charley Noecker, and Farhan Feroz for useful discussions of the term "dispositive null." This work was partially supported by funding from the Center for Exoplanets and Habitable Worlds, which is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. The authors appreciate the significant Keck observing time and associated funding support from NASA for the study of long-period planets and multiplanet systems. J.T.W. and S.X.W. acknowledge support from NASA Origins of Solar Systems grant NNX10AI52G. The work of W.D.C., M.E., and P.J.M. was supported by NASA Origins of Solar Systems Grant NNX09AB30G. E.B.F. and M.J.P. were supported by NASA Origins of Solar Systems grant NNX09AB35G. D.D. is supported by a University of British Columbia Four Year Fellowship. The work herein is based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The Hobby–Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly. This work has made use of the Exoplanet Orbit Database at exoplanets.org, the Extrasolar Planets Encyclopedia at exoplanet. eu, and of NASA's Astrophysics Data System Bibliographic Services.

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