A星的年龄I：大熊座移动星群恒星的干涉测量观测和年龄估计
The Ages of A-Stars I: Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group
摘要：
利用CHARA阵列上的经典、CLIMB和PAVO光束合成器，我们观测并空间分辨了附近大熊座移动群中的一组7颗A型星。其中至少有四颗恒星具有较大的旋转速度（$v \sin i$ $\gtrsim$ 170 $\mathrm{km~s^{-1}}$），并且预计是扁圆的。这些干涉测量、恒星观测到的光度能量分布和$v \sin i$值被用来计算构造扁圆星模型，从这些模型中可以计算恒星的性质（倾角、自转速度、半径和有效温度作为纬度的函数等）。决心已定将结果与MESA恒星演化模型（Paxton et al. 2011，2013）进行比较，以确定质量和年龄。这项新技术的价值在于，它能够估计快速旋转恒星的基本特性，而无需对恒星进行全面成像。因此，它可以适用于恒星的大小相当于干涉分辨率的限制，而不是那些是几倍大于限制。在共演化的假设下，年龄的分布可以用来检验这里提出的处方和快速旋转恒星的MESA进化代码。我们验证的技术，我们结合这些年龄估计，并确定年龄的移动组为414 $\pm$ 23百万年，这是一致的，但比以前的估计更精确。
英文摘要：
We have observed and spatially resolved a set of seven A-type stars in the nearby Ursa Major moving group with the Classic, CLIMB, and PAVO beam combiners on the CHARA Array. At least four of these stars have large rotational velocities ($v \sin i$ $\gtrsim$ 170 $\mathrm{km~s^{-1}}$) and are expected to be oblate. These interferometric measurements, the stars' observed photometric energy distributions, and $v \sin i$ values are used to computationally construct model oblate stars from which stellar properties (inclination, rotational velocity, and the radius and effective temperature as a function of latitude, etc.) are determined. The results are compared with MESA stellar evolution models (Paxton et al. 2011, 2013) to determine masses and ages. The value of this new technique is that it enables the estimation of the fundamental properties of rapidly rotating stars without the need to fully image the star. It can thus be applied to stars with sizes comparable to the interferometric resolution limit as opposed to those that are several times larger than the limit. Under the assumption of coevality, the spread in ages can be used as a test of both the prescription presented here and the MESA evolutionary code for rapidly rotating stars. With our validated technique, we combine these age estimates and determine the age of the moving group to be 414 $\pm$ 23 Myr, which is consistent with, but much more precise than previous estimates.
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