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 Ramirez, Ivan and Shetrone, Matthew 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. The Astrophysical Journal, 818 (1). pp. 1-20. ISSN 0004-637X

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Abstract

We report the detection of two new long-period giant planets orbiting the stars HD 95872 and HD 162004 ({\psi }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 {\psi }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 {\psi }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, {\psi }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.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version made accessible, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 05 Jul 2016 04:17
Last Modified: 17 Aug 2017 05:19
Uncontrolled Keywords: planetary systems – stars: activity – techniques: radial velocities
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.3847/0004-637X/818/1/34
URI: http://eprints.usq.edu.au/id/eprint/28918

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