光干涉测量法对天鹅座χ脉动的成像一种新的推求Mira星距离和质量的方法
The Pulsation of Chi Cygni Imaged by Optical Interferometry; a Novel Technique to Derive Distance and Mass of Mira Stars
摘要：
我们提出了红外干涉成像的S-型Mira恒星池天鹅座。在2005-2006年期间，使用IOTA光学干涉仪（H波段）在四个不同的时期观测了该物体。图像显示恒星直径的变化高达40%，以及边缘变暗和恒星不均匀性的显着变化。模型拟合给出了精确的恒星直径随时间变化的值，并揭示了温暖的分子层的存在和位移。经临边暗化校正后的恒星半径平均值为12.1质量，振幅脉动为5.1质量。在相位0.94+/-0.01时观察到最小直径。几天后在1.02+/-0.02阶段观察到最高温度。我们还表明，结合CO（Δ v = 3）径向速度测量的分子层的角加速度产生一个5.9+/-1.5 mas视差。在80%的脉动周期中，CO分子的恒定加速度使我们有理由认为这是一个自由落体层。这个加速度与一个由2.1（+1.5/-0.7）太阳质量的恒星产生的引力场是相容的。这最后一个值是在协议与基本模式的衰减器模型。我们预见，包括在径向速度与干涉角测量相结合的技术的发展，最终允许总映射的速度，密度和位置的脉动驱动的大气中的不同物种。
英文摘要：
We present infrared interferometric imaging of the S-type Mira star Chi Cygni. The object was observed at four different epochs in 2005-2006 with the IOTA optical interferometer (H band). Images show up to 40% variation in the stellar diameter, as well as significant changes in the limb darkening and stellar inhomogeneities. Model fitting gave precise time-dependent values of the stellar diameter, and reveals presence and displacement of a warm molecular layer. The star radius, corrected for limb darkening, has a mean value of 12.1 mas and shows a 5.1mas amplitude pulsation. Minimum diameter was observed at phase 0.94+/-0.01. Maximum temperature was observed several days later at phase 1.02+/-0.02. We also show that combining the angular acceleration of the molecular layer with CO (Delta v = 3) radial velocity measurements yields a 5.9+/-1.5 mas parallax. The constant acceleration of the CO molecules -- during 80% of the pulsation cycle -- lead us to argument for a free-falling layer. The acceleration is compatible with a gravitational field produced by a 2.1(+1.5/-0.7) solar mass star. This last value is in agreement with fundamental mode pulsator models. We foresee increased development of techniques consisting in combining radial velocity with interferometric angular measurements, ultimately allowing total mapping of the speed, density, and position of the diverse species in pulsation driven atmospheres.
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