Evidence for a long-period planet orbiting ε Eridani

被引:190
作者
Hatzes, AP [1 ]
Cochran, WD
McArthur, B
Baliunas, SL
Walker, GAH
Campbell, B
Irwin, AW
Yang, S
Kürster, M
Endl, M
Els, S
Butler, RP
Marcy, GW
机构
[1] Univ Texas, McDonald Observ, Austin, TX 78712 USA
[2] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
[3] Univ British Columbia, Dept Phys & Astrophys, Vancouver, BC V6T 1Z4, Canada
[4] Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada
[5] European So Observ, Santiago 19, Chile
[6] Agr Univ Vienna, Inst Astron, A-1180 Vienna, Austria
[7] Univ Heidelberg, Inst Theoret Astrophys, D-69121 Heidelberg, Germany
[8] Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA
[9] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
关键词
planetary systems; stars : individual (epsilon Eridani); stars; low-mass; brown dwarfs; techniques : radial velocities;
D O I
10.1086/317319
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
High-precision radial velocity (RV) measurements spanning the years 1980.8-2000.0 are presented for the nearby (3.22 pc) K2 V star epsilon Eri. These data, which represent a combination of six independent data sets taken with four different telescopes, show convincing variations with a period of approximate to7 yr. A least-squares orbital solution using robust estimation yields orbital parameters of period P = 6.9 yr, velocity amplitude K = 19 m s(-1), eccentricity e = 0.6, projected companion mass M sin i = 0.86 M-Jupiter and semimajor axis a(2) = 3.4 AU. Ca II H and K S-index measurements spanning the same time interval show significant variations with periods of 3 and 20 yr yet none at the RV period. If magnetic activity were responsible for the RV variations, then it produces a significantly different period than is seen in the Ca II data. Given the lack of Ca II variation with the same period as that found in the RV measurements, the long-lived and coherent nature of these variations, and the high eccentricity of the implied orbit, Keplerian motion due to a planetary companion seems to be the most likely explanation for the observed RV variations. The wide angular separation of the planet from the star (approximately 1 ") and the long orbital period make this planet a prime candidate for both direct imaging and space-based astrometric measurements.
引用
收藏
页码:L145 / L148
页数:4
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