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arXiv 1108.2641astro-ph.EP
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WASP-50 b:一个热木星过境一个中等活跃的太阳型恒星

WASP-50b: a hot Jupiter transiting a moderately active solar-type star

M. Gillon, A. P. Doyle, M. Lendl, P. F. L. Maxted, A. H. M. J. Triaud, D. R. Anderson, S. C. C. Barros, J. Bento, A. Collier-Cameron, B. Enoch, F. Faedi, C. Hel… 展开作者

M. Gillon, A. P. Doyle, M. Lendl, P. F. L. Maxted, A. H. M. J. Triaud, D. R. Anderson, S. C. C. Barros, J. Bento, A. Collier-Cameron, B. Enoch, F. Faedi, C. Hellier, E. Jehin, P. Magain, J. Montalban, F. Pepe, D. Pollacco, D. Queloz, B. Smalley, D. Segransan, A. M. S. Smith, J. Southworth, S. Udry, R. G. West, P. J. Wheatley

摘要:

我们报道了WASP凌日巡天在南波江座发现的一颗巨行星(0.0295 ± 0.0009AU),它围绕着一颗中等亮度(V=11.6,K=10)的G9矮星(0.89 ± 0.08M_sun,0.84 ± 0.03R_sun)运行。由于TRAPPIST和Euler望远镜获得的高精度后续测光和光谱学,这颗行星WASP-50 b的质量和大小分别被限制在1.47+-0.09 M_jup和1.15+-0.05 R_jup。凌日星历是2455558.6120(+-0.0002)+ N x 1.955096(+-0.000005)HJD_UTC。这颗行星的大小与辐射巨行星的基本模型一致。色球活动(log R '_HK = -4.67)和自转周期(P_rot = 16.3 ± 0.5天)表明,恒星的年龄为0.8 ± 0.4Gy,这与基于测量的恒星参数的恒星演化估计不符(rho_star = 1.48 ± 0.10 rho_sun,Teff = 5400 ± 100 K,[Fe/H]= -0.12 ± 0.08),年龄为7 ± 3.5 Gy。这种差异可以用行星对恒星的潮汐和磁场影响来解释,这与观测结果非常一致,即拥有热彗星的恒星往往表现出更快的旋转和磁场活动(Pont 2009; Hartman 2010)。我们测量的恒星倾角为84(-31,+6)度,不利于高恒星的相似性。WASP-50 b的辐射量很大,而且其主星的体积相对较小,因此是掩星分光光度法的一个很好的目标,这使得它能够限制Knutson等人(2010年)提出的热彗星的大气热分布与其主星色球活动之间的关系。

英文摘要:

We report the discovery by the WASP transit survey of a giant planet in a close orbit (0.0295+-0.0009 AU) around a moderately bright (V=11.6, K=10) G9 dwarf (0.89+-0.08 M_sun, 0.84+-0.03 R_sun) in the Southern constellation Eridanus. Thanks to high-precision follow-up photometry and spectroscopy obtained by the telescopes TRAPPIST and Euler, the mass and size of this planet, WASP-50b, are well constrained to 1.47+-0.09 M_jup and 1.15+-0.05 R_jup, respectively. The transit ephemeris is 2455558.6120 (+-0.0002) + N x 1.955096 (+-0.000005) HJD_UTC. The size of the planet is consistent with basic models of irradiated giant planets. The chromospheric activity (log R'_HK = -4.67) and rotational period (P_rot = 16.3+-0.5 days) of the host star suggest an age of 0.8+-0.4 Gy that is discrepant with a stellar-evolution estimate based on the measured stellar parameters (rho_star = 1.48+-0.10 rho_sun, Teff = 5400+-100 K, [Fe/H]= -0.12+-0.08) which favours an age of 7+-3.5 Gy. This discrepancy could be explained by the tidal and magnetic influence of the planet on the star, in good agreement with the observations that stars hosting hot Jupiters tend to show faster rotation and magnetic activity (Pont 2009; Hartman 2010). We measure a stellar inclination of 84 (-31,+6) deg, disfavouring a high stellar obliquity. Thanks to its large irradiation and the relatively small size of its host star, WASP-50b is a good target for occultation spectrophotometry, making it able to constrain the relationship between hot Jupiters' atmospheric thermal profiles and the chromospheric activity of their host stars proposed by Knutson et al. (2010).

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