Stellar and substellar companions of nearby stars from Gaia DR2
Stellar and substellar companions of nearby stars from Gaia DR2
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DOI：
10.1051/0004-6361/201834371
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发表时间：
2018-11
影响因子：
6.5
通讯作者：
P. Kervella;Frédéric Arenou;F. Mignard;F. Th'evenin
中科院分区：
文献类型：
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作者：
P. Kervella;Frédéric Arenou;F. Mignard;F. Th'evenin
上下文对邻近恒星的恒星和亚恒星伴星的普查在很大程度上是不完整的，特别是对低质量的褐矮星和长周期的系外行星。然而，它是根本重要的恒星和行星的形成和演化机制的理解。对于高精度的天体测量来说，附近的恒星是特别有利的目标。目标。我们的目标是描述存在的物理同伴的恒星和亚恒星质量的轨道周围的恒星。方法.轨道上的次级天体通过它们的引力反射运动影响它们的母星星的自行。使用HIPPARCOS和盖亚的第二次数据发布（GDR 2）目录，我们确定了这两个目录共同的恒星的长期自行。然后，我们在长期自行矢量和GDR 2（或HIPPARCOS）测量值之间搜索自行异常（PMa），这表明存在扰动的次级物体。我们集中我们的分析在6741附近的恒星位于50 pc，我们还提出了一个目录的PMa的99%的HIPPARCOS目录（117000颗恒星）。结果30%的恒星的PMa大于3σ。PMa使我们能够探测到轨道上的同伴，或者对它们的存在设定严格的限制。我们提出了一些插图的PMa分析有趣的目标。我们设定了0.1 - 0.3 MJ的上限，以1到10 Au（Porb = 3到100年）之间的潜在行星为Proxima轨道。我们确认Proxima与α Cen引力结合。我们恢复了已知的伴星E1 Eri、E1 Ind、Ross 614和β Pic的质量。我们还探测到了一颗可能有几个木星质量的行星绕着鲸鱼座τ运行的信号。结论.基于仅22个月的数据，GDR 2具有局限性。但是它与HIPPARCOS目录的结合导致了非常高精度的PMa矢量，这已经使我们能够对附近物体的二进制设置有价值的约束。GDR 2已经能够以σ（ΔvT）= 1.0 m s−1/秒差距距离的中位精度检测切向速度异常。这种类型的分析打开了可能性，以确定长期的轨道同伴，否则无法访问。对于长轨道周期，盖亚与径向速度和过境技术（对短轨道周期更敏感）的互补性似乎已经非常强大。
Context. The census of stellar and substellar companions of nearby stars is largely incomplete, in particular toward the low-mass brown dwarf and long-period exoplanets. It is, however, fundamentally important in the understanding of the stellar and planetary formation and evolution mechanisms. Nearby stars are particularly favorable targets for high precision astrometry. Aims. We aim to characterize the presence of physical companions of stellar and substellar mass in orbit around nearby stars. Methods. Orbiting secondary bodies influence the proper motion of their parent star through their gravitational reflex motion. Using the HIPPARCOS and Gaia’s second data release (GDR2) catalogs, we determined the long-term proper motion of the stars common to these two catalogs. We then searched for a proper motion anomaly (PMa) between the long-term proper motion vector and the GDR2 (or HIPPARCOS) measurements, indicative of the presence of a perturbing secondary object. We focussed our analysis on the 6741 nearby stars located within 50 pc, and we also present a catalog of the PMa for ≳99% of the HIPPARCOS catalog (≈117 000 stars). Results. 30% of the stars studied present a PMa greater than 3σ. The PMa allows us to detect orbiting companions, or set stringent limits on their presence. We present a few illustrations of the PMa analysis to interesting targets. We set upper limits of 0.1−0.3 MJ to potential planets orbiting Proxima between 1 and 10 au (Porb = 3 to 100 years). We confirm that Proxima is gravitationally bound to α Cen. We recover the masses of the known companions of ϵ Eri, ϵ Ind, Ross 614 and β Pic. We also detect the signature of a possible planet of a few Jovian masses orbiting τ Ceti. Conclusions. Based on only 22 months of data, the GDR2 has limitations. But its combination with the HIPPARCOS catalog results in very high accuracy PMa vectors, that already enable us to set valuable constraints on the binarity of nearby objects. The detection of tangential velocity anomalies at a median accuracy of σ(ΔvT) = 1.0 m s−1 per parsec of distance is already possible with the GDR2. This type of analysis opens the possibility to identify long period orbital companions otherwise inaccessible. For long orbital periods, Gaia’s complementarity to radial velocity and transit techniques (that are more sensitive to short orbital periods) already appears to be remarkably powerful.