Transiting exoplanets from the CoRoT space mission - XXIV. CoRoT-25b and CoRoT-26b: two low-density giant planets
Transiting exoplanets from the CoRoT space mission - XXIV. CoRoT-25b and CoRoT-26b: two low-density giant planets
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DOI：
10.1051/0004-6361/201321462
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发表时间：
2013-07
影响因子：
6.5
通讯作者：
J. Almenara;F. Bouchy;P. Gaulme;M. Deleuil;M. Havel;D. Gandolfi;H. Deeg;G. Wuchterl;T. Guillot;B. Gardès;T. Pasternacki;S. Aigrain;R. Alonso;M. Auvergne;A. Baglin;A. Bonomo;P. Bordé;J. Cabrera;S. Carpano;W. Cochran;S. Csizmadia;C. Damiani;R. Díaz;R. Dvorak;M. Endl;A. Erikson;S. Ferraz-Mello;M. Fridlund;G. Hébrard;M. Gillon;E. Guenther;A. Hatzes;A. Léger;H. Lammer;P. Macqueen;T. Mazeh;C. Moutou;M. Ollivier;A. Ofir;M. Pätzold;H. Parviainen;D. Queloz;H. Rauer;D. Rouan;A. Santerne;B. Samuel;J. Schneider;L. Tal-Or;B. Tingley;J. Weingrill
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文献类型：
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作者：
J. Almenara;F. Bouchy;P. Gaulme;M. Deleuil;M. Havel;D. Gandolfi;H. Deeg;G. Wuchterl;T. Guillot;B. Gardès;T. Pasternacki;S. Aigrain;R. Alonso;M. Auvergne;A. Baglin;A. Bonomo;P. Bordé;J. Cabrera;S. Carpano;W. Cochran;S. Csizmadia;C. Damiani;R. Díaz;R. Dvorak;M. Endl;A. Erikson;S. Ferraz-Mello;M. Fridlund;G. Hébrard;M. Gillon;E. Guenther;A. Hatzes;A. Léger;H. Lammer;P. Macqueen;T. Mazeh;C. Moutou;M. Ollivier;A. Ofir;M. Pätzold;H. Parviainen;D. Queloz;H. Rauer;D. Rouan;A. Santerne;B. Samuel;J. Schneider;L. Tal-Or;B. Tingley;J. Weingrill
我们报告了两颗凌日系外行星CoRoT-25b和CoRoT-26b的发现，这两颗行星都是低密度的，其中一颗处于土星质量区域。对于每一颗恒星，通过光学测光和径向速度测量进行的地面互补观测确保了凌日天体的行星性质，并使我们能够充分描述它们的特征。对于CoRoT-25b，我们发现其行星质量为0.27，类似于0.04 M-JUP，半径为1.08(-0.10)(+0.3)R-JUP，因此平均密度为0.15(-0.06)(+0.15)g cm(-3)。这颗行星围绕一颗F9主序恒星运行，周期为4.86天，V星等为15.0，太阳金属丰度，年龄为4.5(-2.0)(+1.8)-Gyr。Corot-26b围绕着一颗轻微演化的G5恒星运行，其年龄为9.06+/-1.5-Gyr，周期为4.20天，具有太阳金属丰度，V等为15.8。其质量为0.52+/-0.05MJup，半径为1.26(-0.07)(+0.13)R-JUP，平均密度为0.28(-0.07)(+0.09)g cm(-3)，属于低质量热木星种群。行星演化模型允许我们估计这两颗重元素质量分数分别为0.52(-0.15)(+0.08)和0.26(-0.08)(+0.05)的行星的核心质量为地球质量的几十倍，假设传入通量的一小部分在行星中心耗散。此外，这些模型表明，CoRoT-26b比标准模型所能解释的要大得多，这表明恒星加热的耗散可能导致了这个大小。
We report the discovery of two transiting exoplanets, CoRoT-25b and CoRoT-26b, both of low density, one of which is in the Saturn mass-regime. For each star, ground-based complementary observations through optical photometry and radial velocity measurements secured the planetary nature of the transiting body and allowed us to fully characterize them. For CoRoT-25b we found a planetary mass of 0.27 similar to 0.04 M-Jup, a radius of 1.08(-0.10)(+0.3) R-Jup and hence a mean density of 0.15(-0.06)(+ 0.15) g cm(-3). The planet orbits an F9 mainsequence star in a 4.86-day period, that has a V magnitude of 15.0, solar metallicity, and an age of 4.5(-2.0) (+1.8)-Gyr. CoRoT-26b orbits a slightly evolved G5 star of 9.06 +/- 1.5-Gyr age in a 4.20-day period that has solar metallicity and a V magnitude of 15.8. With a mass of 0.52 +/- 0.05 MJup, a radius of 1.26(-0.07)(+0.13) R-Jup, and a mean density of 0.28(-0.07)(+0.09) g cm(-3), it belongs to the low-mass hot-Jupiter population. Planetary evolution models allowed us to estimate a core mass of a few tens of Earth mass for the two planets with heavy-element mass fractions of 0.52(-0.15)(+0.08) and 0.26(-0.08)(+0.05), respectively, assuming that a small fraction of the incoming flux is dissipated at the center of the planet. In addition, these models indicate that CoRoT-26b is anomalously large compared with what standard models could account for, indicating that dissipation from stellar heating could cause this size.