K2-106, a system containing a metal-rich planet and a planet of lower density
K2-106, a system containing a metal-rich planet and a planet of lower density
复制标题
DOI：
10.1051/0004-6361/201730885
复制
发表时间：
2017-05
影响因子：
6.5
通讯作者：
E. Guenther;O. Barragán;F. Dai;Davide Gandolfi;T. Hirano;M. Fridlund;M. Fridlund;M. Fridlund;L. Fossati;A. Chau;R. Helled;J. Korth;J. Prieto-Arranz;J. Prieto-Arranz;D. Nespral;D. Nespral;G. Antoniciello;H. Deeg;H. Deeg;M. Hjorth;S. Grziwa;S. Albrecht;A. Hatzes;H. Rauer;H. Rauer;S. Csizmadia;Alexis M. S. Smith;J. Cabrera;N. Narita;P. Arriagada;J. Burt;R. P. Butler;W. Cochran;J. Crane;P. Eigmueller;A. Erikson;J. Johnson;A. Kiilerich;D. Kubyshkina;E. Pallé;E. Pallé;C. M. Persson;M. Pätzold;S. Sabotta;B. Sato;S. Shectman;J. Teske;I. Thompson;V. V. Eylen-V.;G. Nowak;G. Nowak;A. Vanderburg;J. Winn;R. Wittenmyer
中科院分区：
文献类型：
--
作者：
E. Guenther;O. Barragán;F. Dai;Davide Gandolfi;T. Hirano;M. Fridlund;M. Fridlund;M. Fridlund;L. Fossati;A. Chau;R. Helled;J. Korth;J. Prieto-Arranz;J. Prieto-Arranz;D. Nespral;D. Nespral;G. Antoniciello;H. Deeg;H. Deeg;M. Hjorth;S. Grziwa;S. Albrecht;A. Hatzes;H. Rauer;H. Rauer;S. Csizmadia;Alexis M. S. Smith;J. Cabrera;N. Narita;P. Arriagada;J. Burt;R. P. Butler;W. Cochran;J. Crane;P. Eigmueller;A. Erikson;J. Johnson;A. Kiilerich;D. Kubyshkina;E. Pallé;E. Pallé;C. M. Persson;M. Pätzold;S. Sabotta;B. Sato;S. Shectman;J. Teske;I. Thompson;V. V. Eylen-V.;G. Nowak;G. Nowak;A. Vanderburg;J. Winn;R. Wittenmyer
质量在2到15倍地球质量范围内的行星非常多样。其中一些密度较低，而另一些则密度很高。通过测量质量和半径，可以确定行星的平均密度、结构和组成。这些参数也为我们提供了有关它们形成和演化以及大气损失可能过程的重要信息。
我们确定了环绕K2 - 106运行的两颗凌星行星的质量、半径和平均密度。内侧行星的轨道周期极短，为0.57天，外侧行星的周期为13.3天。尽管这两颗行星质量相近，但它们的密度却大不相同。对于K2 - 106b，我们得出其质量\(M_b = 8.36_{ - 0.94}^{ + 0.96}\)倍地球质量，半径\(R_b = 1.52 \pm 0.16\)倍地球半径，以及高达\(13.1_{ - 3.6}^{ + 5.4}\)克/立方厘米的密度。对于K2 - 106c，我们得到\(M_c = 5.8_{ - 3.0}^{ + 3.3}\)倍地球质量，\(R_c = 2.50_{ - 0.26}^{ + 0.27}\)倍地球半径，以及相对较低的\(2.0_{ - 1.1}^{ + 1.6}\)克/立方厘米的密度。
由于该系统包含两颗质量几乎相同但与主恒星距离不同的行星，它是研究大气逃逸的绝佳实验室。与大气损失过程理论相符的是，外侧行星很可能拥有以氢为主的大气层。内侧行星的质量和半径与预测其铁核占自身质量\(80_{ + 20}^{ - 30}\%\)的理论模型相符。如此高的金属含量令人惊讶，特别是考虑到该恒星具有普通（太阳）的金属丰度。我们讨论了这颗不寻常行星的各种可能形成情景。
Planets in the mass range from 2 to 15 M_Earth are very diverse. Some of them have low densities, while others are very dense. By measuring the masses and radii, the mean densities, structure, and composition of the planets are constrained. These parameters also give us important information about their formation and evolution, and about possible processes for atmospheric loss.We determined the masses, radii, and mean densities for the two transiting planets orbiting K2-106. The inner planet has an ultra-short period of 0.57 days. The period of the outer planet is 13.3 days. Although the two planets have similar masses, their densities are very different. For K2-106b we derive Mb=8.36-0.94+0.96 M_Earh, Rb=1.52+/-0.16 R_Earth, and a high density of 13.1-3.6+5.4 g/cm^3. For K2-106c, we find Mc=5.8-3.0+3.3 M_Earth, Rc=2.50-0.26+0.27 R_Earth and a relatively low density of 2.0-1.1+1.6 g/cm^3.Since the system contains two planets of almost the same mass, but different distances from the host star, it is an excellent laboratory to study atmospheric escape. In agreement with the theory of atmospheric-loss processes, it is likely that the outer planet has a hydrogen-dominated atmosphere. The mass and radius of the inner planet is in agreement with theoretical models predicting an iron core containing 80+20-30% of its mass. Such a high metal content is surprising, particularly given that the star has an ordinary (solar) metal abundance. We discuss various possible formation scenarios for this unusual planet.