论文标题
2MASS J044435686+3723033 B：在$β$ pictoris移动组中潜在成员的年轻同伴
2MASS J04435686+3723033 B: A Young Companion at the Substellar Boundary with Potential Membership in the $β$ Pictoris Moving Group
论文作者
论文摘要
我们提出了2mass J04435750+3723031的详细表征，这是一个低质量的伴侣，绕着年轻的M2星，2MASS J04435686+3723033，7.6 arcSeceConds（550 au），具有23 Myr $β$ pictoris the $β$β$ pictoris Moving Group（550 au）。使用IRTF/spex的伴侣的近红外光谱，我们发现了光谱的M6 $ \ pm $ 1 $ 1，以及通过年龄敏感的吸收线和低表面重力指数（VL-G）的青年指示。宿主中的H $α$排放和锂吸收支持了很小的年龄。我们重新评估了该系统的成员资格，发现它是使用$ GAIA $可交换$ gaia $ pmg的$β$ pmg的差距一致的运动匹配，并为主机和伴侣提供了新的径向速度。如果该系统确实属于$β$ pmg，那将是一个运动学异常值，与其他类似的超级物体（如PZ TEL B）相比，该伴侣将是过度发光的。这将表明2M0443+3723 B可能是棕色矮人二进制（$ \ $ 52+52+52 m $ _ $ _ \ MATHRM {JUP} $，如果相等，则为99 $ \ pm $ \ pm $ 5 m $ _ $ _ \ mathrm {jup} $，如果是单身），并且将成为六个替代的伴侣。为了检验这一假设，我们用Keck II/Nirc2获得了NIR AO图像，但它们并不能解决伴侣的二进制文件，将其降至$ \ sim $ 3 $ 3 au的衍射极限。如果2M0443+3723 AB不属于任何移动组，则其年龄更不确定。在这种情况下，它仍然很年轻（$ \ lyssim $ 30 Myr），并且同伴的隐含质量将在$ \ sim $ 30--110 m $ _ \ mathrm {jup} $之间。
We present a detailed characterization of 2MASS J04435750+3723031, a low-mass companion orbiting the young M2 star, 2MASS J04435686+3723033, at 7.6 arcseconds (550 AU) with potential membership in the 23 Myr $β$ Pictoris moving group ($β$PMG). Using near-infrared spectroscopy of the companion from IRTF/SpeX we have found a spectral type of M6 $\pm$ 1 and indications of youth through age-sensitive absorption lines and a low surface gravity index (VL-G). A young age is supported by H$α$ emission and lithium absorption in the host. We re-evaluate the membership of this system and find that it is a marginally consistent kinematic match to the $β$PMG using $Gaia$ parallaxes and new radial velocities for the host and companion. If this system does belong to the $β$PMG, it would be a kinematic outlier and the companion would be over-luminous compared to other similar ultracool objects like PZ Tel B; this would suggest 2M0443+3723 B could be a close brown dwarf binary ($\approx$52+52 M$_\mathrm{Jup}$ if equal-flux, compared with 99 $\pm$ 5 M$_\mathrm{Jup}$ if single), and would make it the sixth substellar companion in this group. To test this hypothesis, we acquired NIR AO images with Keck II/NIRC2, but they do not resolve the companion to be a binary down to the diffraction limit of $\sim$3 AU. If 2M0443+3723 AB does not belong to any moving group then its age is more uncertain. In this case it is still young ($\lesssim$30 Myr), and the implied mass of the companion would be between $\sim$30--110 M$_\mathrm{Jup}$.
