Misaligned Circumstellar Disks and Orbital Motion of the Young Binary XZ Tau
Misaligned Circumstellar Disks and Orbital Motion of the Young Binary XZ Tau
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DOI：
10.3847/1538-4357/ac0dc3
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
T. Ichikawa;M. Kido;Daisuke Takaishi;Y. Shimajiri;Y. Tsukamoto;S. Takakuwa
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文献类型：
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作者：
T. Ichikawa;M. Kido;Daisuke Takaishi;Y. Shimajiri;Y. Tsukamoto;S. Takakuwa
我们报告了我们对第二类双星XZ Tau在3、4和6波段的多历元(2015年-2017年)阿塔卡马大毫米/亚毫米阵列记录数据的分析。毫米尘埃连续谱图像显示了单个双星XZ Tau A和B周围致密的、未分辨的(r≲15 Au)绕星盘(CSD)，预计分离出∼39 Au。与这些CSD相关的12CO(2-1)发射跟踪开普勒式旋转，其旋转轴彼此错位(XZ Tau A的P.A.∼−5°和XZ Tau B的∼130°)。两颗CSD(VLSR∼6.0kM S−1)的相似系统速度表明，这两颗双星的轨道平面接近天空平面。从多历元的ALMA数据中，我们还确定了双星的相对轨道运动。结合以前的近红外数据，我们发现椭圆轨道(e=0.742−0.034+0.025，a=0.“172−0.”003+0.“002，ω=−54.°2−4.°7+2.°0)优于圆形轨道。我们的结果表明，两个CSD和XZ Tau系统的轨道平面都是相互错位的，并讨论了产生这种组态的可能机制。我们对多时代的ALMA档案数据的分析证明了用ALMA进行时间域科学的可行性。
We report our analyses of the multi-epoch (2015–2017) Atacama Large Millimeter/submillimeter Array (ALMA) archival data of the Class II binary system XZ Tau at Bands 3, 4, and 6. The millimeter dust-continuum images show compact, unresolved (r ≲ 15 au) circumstellar disks (CSDs) around the individual binary stars, XZ Tau A and B, with a projected separation of ∼39 au. The 12CO (2–1) emission associated with those CSDs traces the Keplerian rotations, whose rotational axes are misaligned with each other (P.A. ∼ −5° for XZ Tau A and ∼130° for XZ Tau B). The similar systemic velocities of the two CSDs (V LSR ∼ 6.0 km s−1) suggest that the orbital plane of the binary stars is close to the plane of the sky. From the multi-epoch ALMA data, we have also identified the relative orbital motion of the binary. Along with the previous NIR data, we found that the elliptical orbit (e = 0.742−0.034+0.025 , a=0.″172−0.″003+0.″002 , and ω=−54.°2−4.°7+2.°0 ) is preferable to the circular orbit. Our results suggest that the two CSDs and the orbital plane of the XZ Tau system are all misaligned with each other, and possible mechanisms to produce such a configuration are discussed. Our analyses of the multi-epoch ALMA archival data demonstrate the feasibility of time-domain science with ALMA.