Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS-猫眼课题宝

DOI：

10.3847/2041-8213/ac772f

发表时间：

2022-05

期刊：

The Astrophysical Journal Letters

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

M. Kuzuhara;T. Currie;T. Takarada;Timothy D. Brandt;B. Sato;T. Uyama;M. Janson;J. Chilcote;T. Tobin;Kellen D. Lawson;Y. Hori;O. Guyon;T. Groff;J. Lozi;S. Vievard;A. Sahoo;V. Deo;N. Jovanovic;K. Ahn;F. Martinache;N. Skaf;E. Akiyama;B. Norris;M. Bonnefoy;K. Hełminiak;T. Kudo;M. McElwain;M. Samland;K. Wagner;J. Wisniewski;Gillian R. Knapp Jungmi Kwon;J. Nishikawa;E. Serabyn;M. Hayashi;Motohide Tamura

我们提出了直接成像的发现，一个亚星伴星在轨道上围绕一个类似太阳的恒星成员的毕宿四开放星系团。到目前为止，还没有通过在毕马座主序恒星周围的直接成像来明确确认其他恒星下的同伴。根据盖亚和依巴谷卫星的天体测量结果，HIP 21152是一颗加速恒星。我们使用SCExao/Charis和Keck/NIRC2的高对比度成像在多个时代检测到了伴星HIP 21152 B。我们还获得了冈山188厘米望远镜的恒星径向速度数据。Charis谱显示，HIP 21152 B的光谱与L/T跃迁相一致，最适合早期的T矮星。我们的轨道模型确定了HIP 21152 B的半长轴和动力学质量分别为17.5−3.8±7.2Au和27.8−5.4+8.4M JUP。最近的调查表明，HIP 21152 B相对于其宿主的质量比为≈2%，位于行星/棕矮星边界附近。从光度演化模型推断的质量估计值略高(33-42M JUP)。HIP 21152 B具有动力学质量，由于该系统的毕宿四成员资格，它的年龄受到很好的限制，将成为理解作为质量和年龄函数的恒星下天体的形成、演化和大气的关键基准。我们的发现是使用精密天体测量学来选择直接成像目标的又一关键概念证明。

We present the direct-imaging discovery of a substellar companion in orbit around a Sun-like star member of the Hyades open cluster. So far, no other substellar companions have been unambiguously confirmed via direct imaging around main-sequence stars in Hyades. The star HIP 21152 is an accelerating star as identified by the astrometry from the Gaia and Hipparcos satellites. We detected the companion, HIP 21152 B, in multiple epochs using the high-contrast imaging from SCExAO/CHARIS and Keck/NIRC2. We also obtained the stellar radial-velocity data from the Okayama 188 cm telescope. The CHARIS spectroscopy reveals that HIP 21152 B’s spectrum is consistent with the L/T transition, best fit by an early T dwarf. Our orbit modeling determines the semimajor axis and the dynamical mass of HIP 21152 B to be 17.5 −3.8+7.2 au and 27.8 −5.4+8.4 M Jup, respectively. The mass ratio of HIP 21152 B relative to its host is ≈2%, near the planet/brown dwarf boundary suggested by recent surveys. Mass estimates inferred from luminosity-evolution models are slightly higher (33–42 M Jup). With a dynamical mass and a well-constrained age due to the system’s Hyades membership, HIP 21152 B will become a critical benchmark in understanding the formation, evolution, and atmosphere of a substellar object as a function of mass and age. Our discovery is yet another key proof of concept for using precision astrometry to select direct-imaging targets.

Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS

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