Direct discovery of the inner exoplanet in the HD 206893 system: Evidence for deuterium burning in a planetary-mass companion
Direct discovery of the inner exoplanet in the HD 206893 system: Evidence for deuterium burning in a planetary-mass companion
复制标题
HD 206893系统中直接发现内系外行星：行星质量伴星中氘燃烧的证据
DOI：
10.1051/0004-6361/202244727
复制
发表时间：
2023
影响因子：
6.5
通讯作者：
Stolker, T.
中科院分区：
文献类型：
--
作者：
Hinkley, S.;Lacour, S.;Marleau, G.-D.;Lagrange, A.-M.;Wang, J. J.;Kammerer, J.;Cumming, A.;Nowak, M.;Rodet, L.;Stolker, T.
AimsHD 206893是一颗附近的碎片盘星，拥有一颗先前发现的褐矮星伴星，轨道距离为10天文单位。长期精确的径向速度（RV）监测，以及系统固有运动的异常，表明系统中存在额外的内部伴体。方法利用正在进行的HARPS光谱仪精确RV测量的信息，以及盖亚宿主恒星天体测量，我们使用VLTI/重力仪器进行了多时期的搜索，以寻找所谓的额外行星。结果我们报告了对伴星HD 206893c的三个历代的高意义探测，这为开普勒轨道运动提供了明确的证据。我们的天体测量以重力提供的~ 50−100 μ弧秒的精度使我们得到HD 206893c的动态质量为12.7 mjupe，轨道距离为3.53 au。我们使用gaiaastrometry和rv对系统中两个伴星的轨道进行拟合，也提供了先前不确定的B分量质量的精确动态估计，因此使我们能够得出系统的年龄为155±15 Myr。我们发现，包含HD 206893c的氘燃烧的理论大气和演化模型，以多云大气模型和“混合序列”（包括从多云到无云的过渡）为参数化，可以很好地同时拟合HD 206893B和c的光度。因此，考虑氘燃烧和云对于理解HD 206893c的光度演化至关重要。除了使用长期的RV信息外，这项工作是直接成像发现真正系外行星的早期例子，部分是由gaiaastrometry指导的。利用gaiaastrometry有望成为未来识别和表征其他直接成像行星的主要技术之一。此外，HD 206893c是一个物体勉强跨越氘燃烧极限，但毫无疑问正在进行氘燃烧的例子。因此，像这样的其他发现可能有助于澄清褐矮星和系外行星之间的区别。最后，这一发现是光学干涉测量法的另一个例子，它可以直接探测和表征它们形成的系外行星，在冰线轨道距离为2 - 4 au的地方。
AimsHD 206893 is a nearby debris disk star that hosts a previously identified brown dwarf companion with an orbital separation of ∼10 au. Long-term precise radial velocity (RV) monitoring, as well as anomalies in the system proper motion, has suggested the presence of an additional, inner companion in the system.MethodsUsing information from ongoing precision RV measurements with the HARPS spectrograph, as well asGaiahost star astrometry, we have undertaken a multi-epoch search for the purported additional planet using the VLTI/GRAVITY instrument.ResultsWe report a high-significance detection over three epochs of the companion HD 206893c, which shows clear evidence for Keplerian orbital motion. Our astrometry with ∼50−100 μarcsec precision afforded by GRAVITY allows us to derive a dynamical mass of 12.7MJupand an orbital separation of 3.53 au for HD 206893c. Our fits to the orbits of both companions in the system use bothGaiaastrometry and RVs to also provide a precise dynamical estimate of the previously uncertain mass of the B component, and therefore allow us to derive an age of 155 ± 15 Myr for the system. We find that theoretical atmospheric and evolutionary models that incorporate deuterium burning for HD 206893c, parameterized by cloudy atmosphere models as well as a “hybrid sequence” (encompassing a transition from cloudy to cloud-free), provide a good simultaneous fit to the luminosity of both HD 206893B and c. Thus, accounting for both deuterium burning and clouds is crucial to understanding the luminosity evolution of HD 206893c.ConclusionsIn addition to using long-term RV information, this effort is an early example of a direct imaging discovery of a bona fide exoplanet that was guided in part byGaiaastrometry. UtilizingGaiaastrometry is expected to be one of the primary techniques going forward for identifying and characterizing additional directly imaged planets. In addition, HD 206893c is an example of an object narrowly straddling the deuterium-burning limit but unambiguously undergoing deuterium burning. Additional discoveries like this may therefore help clarify the discrimination between a brown dwarf and an extrasolar planet. Lastly, this discovery is another example of the power of optical interferometry to directly detect and characterize extrasolar planets where they form, at ice-line orbital separations of 2−4 au.