RETIRED A STARS AND THEIR COMPANIONS. VI. A PAIR OF INTERACTING EXOPLANET PAIRS AROUND THE SUBGIANTS 24 SEXTANIS AND HD 200964

被引：66

作者：

Johnson, John Asher ^{[1
]}

Payne, Matthew ^{[2
]}

Howard, Andrew W. ^{[3
]}

Clubb, Kelsey I. ^{[4
]}

Ford, Eric B. ^{[2
]}

Bowler, Brendan P. ^{[5
]}

Henry, Gregory W. ^{[6
]}

Fischer, Debra A. ^{[7
]}

Marcy, Geoffrey W. ^{[3
]}

Brewer, John M. ^{[7
]}

Schwab, Christian ^{[7
,8
]}

Reffert, Sabine ^{[8
]}

Lowe, Thomas B. ^{[9
]}

机构：

[1] CALTECH, Dept Astrophys, Pasadena, CA 91125 USA

[2] Univ Florida, Dept Astron, Bryant Space Sci Ctr 211, Gainesville, FL 32611 USA

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

[4] San Francisco State Univ, Dept Phys & Astron, San Francisco, CA 94132 USA

[5] Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA

[6] Tennessee State Univ, Ctr Excellence Informat Syst, Nashville, TN 37209 USA

[7] Yale Univ, Dept Astron, New Haven, CT 06511 USA

[8] Heidelberg Univ, Landessternwarte, ZAH, D-69117 Heidelberg, Germany

[9] UCO Lick Observ, Santa Cruz, CA 95064 USA

来源：

ASTRONOMICAL JOURNAL | 2011年 / 141卷 / 01期

关键词：

planets and satellites: detection; planets and satellites: formation; planets and satellites: fundamental parameters; planets and satellites: individual (HD200964 b; HD200964; c; 24 Sex b; 24 Sex c); stars:; individual; (24; Sex; HD200964); techniques: radial velocities; MULTIPLE-PLANET SYSTEMS; SHORT-PERIOD PLANETS; CHAIN MONTE-CARLO; EXTRASOLAR PLANETS; UPSILON-ANDROMEDAE; MAGNETIC ACTIVITY; RADIAL-VELOCITY; GIANT PLANETS; HOT JUPITER; COOL STARS;

D O I：

10.1088/0004-6256/141/1/16

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report radial velocity (RV) measurements of the G-type subgiants 24 Sextanis (= HD 90043) and HD 200964. Both are massive, evolved stars that exhibit periodic variations due to the presence of a pair of Jovian planets. Photometric monitoring with the T12 0.80 m APT at Fairborn Observatory demonstrates both stars to be constant in brightness to <= 0.002 mag, thus strengthening the planetary interpretation of the RV variations. Based on our dynamical analysis of the RV time series, 24 Sex b, c have orbital periods of 452.8 days and 883.0 days, corresponding to semimajor axes 1.333 AU and 2.08 AU, and minimum masses 1.99 M-Jup and 0.86 M-Jup, assuming a stellar mass M-star = 1.54 M-circle dot. HD 200964 b, c have orbital periods of 613.8 days and 825.0 days, corresponding to semimajor axes 1.601 AU and 1.95 AU, and minimum masses 1.99 M-Jup and 0.90 M-Jup, assuming M-star = 1.44 M-circle dot. We also carry out dynamical simulations to properly account for gravitational interactions between the planets. Most, if not all, of the dynamically stable solutions include crossing orbits, suggesting that each system is locked in a mean-motion resonance that prevents close encounters and provides long-term stability. The planets in the 24 Sex system likely have a period ratio near 2: 1, while the HD 200964 system is even more tightly packed with a period ratio close to 4:3. However, we caution that further RV observations and more detailed dynamical modeling will be required to provide definitive and unique orbital solutions for both cases, and to determine whether the two systems are truly resonant.

引用

页数：10