Discovery of a substellar companion to the K2III giant ι Draconis

被引：160

作者：

Frink, S

Mitchell, DS

Quirrenbach, A

Fischer, DA

Marcy, GW

Butler, RP

机构：

[1] Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA

[2] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

[3] Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA

来源：

ASTROPHYSICAL JOURNAL | 2002年 / 576卷 / 01期

关键词：

astrometry; planetary systems; stars : individual (iota Draconis);

D O I：

10.1086/341629

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report precise radial velocity measurements of the K giant iota Dra (HD 137759, HR 5744, HIP 75458), carried out at Lick Observatory, which reveal the presence of a substellar companion orbiting the primary star. A Keplerian fit to the data yields an orbital period of about 536 days and an eccentricity of 0.70. Assuming a mass of 1.05 M-circle dot for iota Dra, the mass function implies a minimum companion mass m(2) sin i of 8.9 M-J, making it a planet candidate. The corresponding semimajor axis is 1.3 AU. The nondetection of the orbital motion by Hipparcos allows us to place an upper limit of 45 M-J on the companion mass, establishing the substellar nature of the object. We estimate that transits in this system could occur already for inclinations as low as 81.5degrees, as a result of the large diameter of the giant star. The companion to iota Dra is the first brown dwarf or planet found to orbit a giant rather than a main-sequence star.

引用

页码：478 / 484

页数：7

共 31 条

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