发表机构
Université Grenoble Alpes; University of California, Berkeley; University of Galway; Université de Bordeaux（格勒诺布尔阿尔卑斯大学; 加州大学伯克利分校; 高威大学; 波尔多大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究对年轻三星系统GG Tau A进行同步轨道拟合，结合天体测量与盘约束，确定了轨道架构并精确估计了各恒星质量，为环三星盘动力学建模奠定基础。
AI 中文摘要
GG Tau $A$ 是一个年轻的三星系统，其中包含密近双星 $Ab_1$--$Ab_2$ 和 $Aa$，周围环绕着一个巨大的环三星盘，其内部存在一个大的空腔，这在双星框架下难以解释。我们的目标是确定 GG Tau $A$ 的轨道结构和各恒星的质量，并评估现有的天体测量和基于盘的约束如何限制可行解的范围。我们使用专门为层级恒星系统开发的 Oracle 程序进行了联合拟合。所有天体测量数据都被置于一个共同的参考框架中，因为历史宽轨道天体测量是相对于 $Ab$ 子系统的未分辨光心给出的。拟合包括一个新宽轨道天体测量历元以及由盘运动学推导出的总恒星质量先验。然后，在后处理中，我们基于观测到的环三星盘中心施加了一个额外的几何约束。拟合得到的轨道解与现有的天体测量和基于盘的约束相容，并提供了各恒星质量的估计。额外的宽轨道历元仅略微缩小了可行解的范围。相比之下，盘中心约束使优选的轨道结构基本不变，但显著收紧了恒星质量的分配。由此得到 $Ab_1$、$Ab_2$ 和 $Aa$ 的后验质量分别为 $0.521^{+0.069}_{-0.051}$、$0.106^{+0.017}_{-0.013}$ 和 $0.79^{+0.10}_{-0.10}$ $M_\odot$。报告的值是后验中位数，区间为16%至84%分位数。需要对两个轨道层级进行联合处理，才能恢复物理上有意义的架构并约束各恒星质量。所得解为未来环三星盘的动力学建模以及检验观测到的空腔是否能进一步约束系统结构提供了基础。
英文摘要
GG Tau $A$ is a young triple system with the close pair, $Ab_1$--$Ab_2$, and $Aa$, surrounded by a massive circumtriple disk with a large inner cavity difficult to explain in a binary framework. We aim to determine the orbital architecture and individual stellar masses of GG Tau $A$ and assess how the available astrometric and disk-based constraints restrict the range of admissible solutions. We performed a joint fit using Oracle, developed specifically for hierarchical stellar systems. All astrometric measurements were placed in a common reference frame, since the historical wide-orbit astrometry is given relative to the unresolved photocenter of the $Ab$ subsystem. The fit included one new wide-orbit astrometric epoch and a prior on the total stellar mass derived from disk kinematics. We then applied, in post-processing, an additional geometrical constraint based on the observed center of the circumtriple disk. The fit yields orbital solutions compatible with the available astrometric and disk-based constraints and provides estimates of the individual stellar masses. The additional wide-orbit epoch only marginally reduces the range of admissible solutions. By contrast, the disk-center constraint leaves the favored orbital architectures largely unchanged but significantly tightens the stellar-mass partition. This yields posterior masses of $0.521^{+0.069}_{-0.051}$, $0.106^{+0.017}_{-0.013}$, and $0.79^{+0.10}_{-0.10}$ $M_\odot$ for $Ab_1$, $Ab_2$, and $Aa$, respectively. The reported values are posterior medians with 16th--84th percentile intervals. A joint treatment of the two orbital levels is required to recover a physically meaningful architecture and constrain the individual stellar masses. The resulting solutions provide a basis for future dynamical modeling of the circumtriple disk and for testing whether the observed cavity can further constrain the system architecture.
CommentsAccepted for publication in A&A on 25 August 2026
DOI：10.1051/0004-6361/202662146
