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Two New Long-Period Giant Planets from the McDonald Observatory Planet Search and Two Stars with Long-Period Radial Velocity Signals Related to Stellar Activity Cycles

Endl, Michael and Brugamyer, Erik J. and Cochran, William D. and MacQueen, Phillip J. and Robertson, Paul and Meschiari, Stefano and Ramírez, Ivan and Shetrone, Matthew D. and Gullikson, Kevin and Johnson, Marshall C. and Wittenmyer, Robert and Horner, Jonathan and Ciardi, David R. and Horch, Elliott and Simon, Attila E. and Howell, Steve B. and Everett, Mark and Caldwell, Caroline and Castanheira, Barbara G. (2016) Two New Long-Period Giant Planets from the McDonald Observatory Planet Search and Two Stars with Long-Period Radial Velocity Signals Related to Stellar Activity Cycles. Astrophysical Journal, 818 (1). Art. No. 34. ISSN 0004-637X.

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We report the detection of two new long-period giant planets orbiting the stars HD 95872 and HD 162004 (ψ^1 Dra B) by the McDonald Observatory planet search. The planet HD 95872b has a minimum mass of 4.6 M_(Jup) and an orbital semimajor axis of 5.2 AU. The giant planet ψ^1 Dra Bb has a minimum mass of 1.5 M_(Jup) and an orbital semimajor axis of 4.4 AU. Both of these planets qualify as Jupiter analogs. These results are based on over one and a half decades of precise radial velocity (RV) measurements collected by our program using the McDonald Observatory Tull Coude spectrograph at the 2.7 m Harlan J. Smith Telescope. In the case of ψ^1 Dra B we also detect a long-term nonlinear trend in our data that indicates the presence of an additional giant planet, similar to the Jupiter–Saturn pair. The primary of the binary star system, ψ^1 Dra A, exhibits a very large amplitude RV variation due to another stellar companion. We detect this additional member using speckle imaging. We also report two cases—HD 10086 and HD 102870 (β Virginis)—of significant RV variation consistent with the presence of a planet, but that are probably caused by stellar activity, rather than reflexive Keplerian motion. These two cases stress the importance of monitoring the magnetic activity level of a target star, as long-term activity cycles can mimic the presence of a Jupiter-analog planet.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Endl, Michael0000-0002-7714-6310
Cochran, William D.0000-0001-9662-3496
Robertson, Paul0000-0003-0149-9678
Johnson, Marshall C.0000-0002-5099-8185
Wittenmyer, Robert0000-0001-9957-9304
Ciardi, David R.0000-0002-5741-3047
Horch, Elliott0000-0003-2159-1463
Howell, Steve B.0000-0002-2532-2853
Everett, Mark0000-0002-0885-7215
Additional Information:© 2016 American Astronomical Society. Received 2015 October 2; accepted 2015 December 7; published 2016 February 4. This work has been made possible through the National Science Foundation (Astrophysics grant AST-1313075) and various NASA grants over the years. We are grateful for their generous support. We also thank the McDonald Observatory Time Allocation committee for its continuing support of this program. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. We would also like to thank all the observers who have helped gather data over the years for the 2.7 m RV planet search program at McDonald Observatory, including Diane Paulson, Stuart I. Barnes, Candice Gray, and Anita Cochran. Finally, we would like to thank the anonymous referee; her/his comments helped to improve this paper. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors 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. Facilities: Gemini Observatory (DSSI), McDonald Observatory (Tull Coudé Spectropgraph), Keck-I Observatory (HIRES).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:planetary systems; stars: activity; techniques: radial velocities
Issue or Number:1
Record Number:CaltechAUTHORS:20160314-095808402
Persistent URL:
Official Citation:Michael Endl et al 2016 ApJ 818 34
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65331
Deposited By: Ruth Sustaita
Deposited On:14 Mar 2016 19:19
Last Modified:09 Mar 2020 13:19

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