论文标题
$ε$ CHA协会的基于Gaia的等距，运动学和空间分析
Gaia-based Isochronal, Kinematic, and Spatial Analysis of the $ε$ Cha Association
论文作者
论文摘要
GAIA数据释放2（DR2）中包含的精确视差，适当的运动和光度测量值提供了重新检查附近年轻移动组（NYMGS）的成员和年龄的机会，即，年龄$ \ \ lyssimsim100 $ Myr的宽松群体在Solar Vicinity中。在这里，我们分析了$ε$ CHA协会（$ε$ CA）的成员和候选人的可用DR2数据，该数据估计年龄为$ \ sim $ 3--5 Myr，以前已被确定为最年轻的Nymgs之一。 $ε$ CA的几十个确认成员包括MP MUS和T CHA，这是两个众所周知的距离原始原理磁盘的最接近的太阳能块的恒星，以及Herbig Ae/Be Star HD 104237a。我们已经使用Gaia DR2数据来确定$ε$ CA成员和候选人的银河系位置，运动学和色量图位置，以便重新评估其成员资格状态，从而完善该组的距离，年龄，多样性和磁盘分数的估计。我们的分析产生了36 \ textit {善意} $ε$ CA成员以及20个临时成员，其中包括3个新成员，在这里被确定为以前已知的$ε$ CA星的共同伴侣。我们确定平均距离为101.0 $ \ pm $ 4.6 PC的$ε$ CA，并确认，在$ 5^{+3} _ { - 2} $ MYR时，$ε$ CA代表了$ \ sim $ 100的地球$ 100。我们将几个新的光度二进制候选者确定，将$ε$ CA的总体多重分数（MF）提高到40 \％，介于年轻T关联和领域的MF之间。
The precise parallax, proper motion, and photometric measurements contained in Gaia Data Release 2 (DR2) offer the opportunity to re-examine the membership and ages of Nearby Young Moving Groups (NYMGs), i.e., loose groups of stars of age $\lesssim100$ Myr in the solar vicinity. Here, we analyze the available DR2 data for members and candidate members of the $ε$ Cha Association ($ε$CA) which, at an estimated age of $\sim$3--5 Myr, has previously been identified as among the youngest NYMGs. The several dozen confirmed members of $ε$CA include MP Mus and T Cha, two of the nearest stars of roughly solar mass that are known to host primordial protoplanetary disks, and the Herbig Ae/Be star HD 104237A. We have used Gaia DR2 data to ascertain the Galactic positions and kinematics and color-magnitude diagram positions of $ε$CA members and candidates, so as to reassess their membership status and thereby refine estimates of the distance, age, multiplicity, and disk fraction of the group. Our analysis yields 36 \textit{bona fide} $ε$CA members, as well as 20 provisional members, including 3 new members identified here as comoving companions to previously known $ε$CA stars. We determine a mean distance to $ε$CA of 101.0$\pm$4.6 pc and confirm that, at an age of $5^{+3}_{-2}$ Myr, $ε$CA represents the youngest stellar group within $\sim$100 pc of Earth. We identify several new photometric binary candidates, bringing the overall multiplicity fraction (MF) of $ε$CA to 40\%, intermediate between the MFs of young T associations and the field.
