The HD 137496 system: A dense, hot super-Mercury and a cold Jupiter
The HD 137496 system: A dense, hot super-Mercury and a cold Jupiter
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HD 137496系统：稠密、炽热的超级水星和寒冷的木星
DOI：
10.1051/0004-6361/202141520
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发表时间：
2022
影响因子：
6.5
通讯作者：
Azevedo Silva T
中科院分区：
文献类型：
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作者：
Azevedo Silva T
目前已知的大多数行星都是半径介于地球和海王星之间的小世界。在这种情况下，行星的特征显示出成分和系统结构的巨大多样性，其分布暗示了多种形成和演化情景。然而，许多行星种群，如高密度行星，样本明显不足，限制了我们对行星形成和演化的理解。AimsNCORES是在HARPS高分辨率光谱仪上进行的一个大型观测项目，旨在确认行星的状态，并测量过境光度测量发现的小型过境行星候选行星的质量，以约束它们的内部组成。方法利用K2卫星的光度测量和HARPS和CORALIE光谱仪测量的径向速度，我们在明亮的（Vmag= 10）和稍微演化的类太阳恒星HD 137496周围寻找行星。结果我们精确地估计了这颗微演化恒星的参数，M*= 1.035±0.022M⊙,R*= 1.587±0.028R⊙,Teff= 5799±61 K，以及化学成分（例如[Fe/H] = - 0.027±0.040指数）。我们发现有两颗行星围绕HD 137496运行。内行星HD 137496 b是一颗超级水星（一颗地球大小的行星，密度与水星相当），质量为mb = 4.04±0.55M⊕，半径为，密度为g cm-3。通过内部建模分析，我们发现这颗行星主要由铁组成，地核占行星质量的70%以上（）。外行星HD 137496 c是一颗偏心（e= 0.477±0.004），长周期（P=天）的巨行星（Mcsinic= 7.66±0.11MJup），我们没有探测到凌日。结论shd 137496 b是迄今为止发现的为数不多的超级水星之一。这里报告的准确表征增强了它作为更好地理解行星系统形成和演化的关键目标的作用。对偏心长周期巨行星伴星的探测也加强了小型过境内行星和长周期气态巨行星之间的联系。
ContextMost of the currently known planets are small worlds with radii between that of the Earth and that of Neptune. The characterization of planets in this regime shows a large diversity in compositions and system architectures, with distributions hinting at a multitude of formation and evolution scenarios. However, many planetary populations, such as high-density planets, are significantly under-sampled, limiting our understanding of planet formation and evolution.AimsNCORES is a large observing program conducted on the HARPS high-resolution spectrograph that aims to confirm the planetary status and to measure the masses of small transiting planetary candidates detected by transit photometry surveys in order to constrain their internal composition.MethodsUsing photometry from the K2 satellite and radial velocities measured with the HARPS and CORALIE spectrographs, we searched for planets around the bright (Vmag= 10) and slightly evolved Sun-like star HD 137496.ResultsWe precisely estimated the stellar parameters,M*= 1.035 ± 0.022M⊙,R*= 1.587 ± 0.028R⊙,Teff= 5799 ± 61 K, together with the chemical composition (e.g. [Fe/H] = −0.027 ± 0.040 dex) of the slightly evolved star. We detect two planets orbiting HD 137496. The inner planet, HD 137496 b, is a super-Mercury (an Earth-sized planet with the density of Mercury) with a mass ofMb= 4.04 ± 0.55M⊕, a radius of and a density of g cm-3. With an interior modeling analysis, we find that the planet is composed mainly of iron, with the core representing over 70% of the planet’s mass ( ). The outer planet, HD 137496 c, is an eccentric (e= 0.477 ± 0.004), long period (P= days) giant planet (Mcsinic= 7.66 ± 0.11MJup) for which we do not detect a transit.ConclusionsHD 137496 b is one of the few super-Mercuries detected to date. The accurate characterization reported here enhances its role as a key target to better understand the formation and evolution of planetary systems. The detection of an eccentric long period giant companion also reinforces the link between the presence of small transiting inner planets and long period gas giants.