Multiepoch Interferometric Study of Mira Variables. I. Narrowband Diameters of RZ Pegasi and S Lacertae
Multiepoch Interferometric Study of Mira Variables. I. Narrowband Diameters of RZ Pegasi and S Lacertae
复制标题
Mira 变量的多历元干涉研究。
DOI：
10.1086/342147
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
G. V. van Belle
中科院分区：
文献类型：
--
作者：
R. Thompson;M. Creech;G. V. van Belle
作为Palomar试验台干涉仪对Mira变星长期监测的一部分，我们报告了富氧Mira S Lac和富碳Mira RZ Peg的近红外高分辨率窄带角尺寸。该数据集跨越了S Lac的三个脉动周期和RZ Peg的两个脉动周期(总计107025个S观测)，是首次对Mira变星的多历元窄带干涉数据进行关联的研究。当校准的能见度数据使用统一的圆盘亮度模型进行拟合时，它们的角直径作为K波段(2.02.4μm)内的波长的函数而出现差异，其来源被认为是两个化学上不同的MIRA的光球中或之上的分子吸收。使用法国观测变量协会(AFOEV)提供的可见光数据，RZ Peg的连续最小尺寸在脉动方面落后0.28±0.02，类似于相关径向速度(CORAVEL)数据中的相位滞后。然而，对于S乳胶来说，连续最小尺寸跟踪视觉最大亮度。基于连续体角直径摆线的平均值，计算了RZPeg和S Lac的基本恒星参数，这两个天体在0.9时相附近都显示出最大的大气伸展，直径分别为2和2.4μm。根据拟合的摆线的平均值，RZPeg的半径RMean=377±111R☉，平均TJeff=2706±36K；S Lac的半径RMean=292±73R☉，平均TJeff=2605±47K。
As part of the long-term monitoring of Mira variables at the Palomar Testbed Interferometer, we report high-resolution narrowband angular sizes of the oxygen-rich Mira S Lac and the carbon-rich Mira RZ Peg in the near-infrared. The data set spans three pulsation cycles for S Lac and two pulsation cycles for RZ Peg (a total of 1070 25 s observations) and represents the first study to correlate multiepoch narrowband interferometric data of Mira variables. When the calibrated visibility data are fitted using a uniform disk brightness model, differences are seen in their angular diameters as a function of wavelength within the K band (2.0-2.4 μm), the source of which is believed to be molecular absorptions in or above the photospheres of the two chemically different Miras. Using visible photometric data provided by the Association Francaise des Observateurs d'Etoiles Variables (AFOEV), the continuum minimum size of RZ Peg lags this by 0.28 ± 0.02 in pulsation, similar to the phase lag found in Correlation Radial Velocities (CORAVEL) data. However, for S Lac, the continuum minimum size tracks the visual maximum brightness. Based on the mean of the continuum angular diameter cycloids, basic stellar parameters are computed for both RZ Peg and S Lac, with both showing maximum atmospheric extension with respect to the 2.0 and 2.4 μm diameters near phase 0.9. Using the mean value of the fitted cycloids, RZ Peg has a radius Rmean = 377 ± 111 R☉ and a mean Teff = 2706 ± 36 K; S Lac has a radius Rmean = 292 ± 73 R☉ and a mean Teff = 2605 ± 47 K. The dominant source of error in the radii is the large uncertainty in the distances to these two stars.