标题： CHARA阵列K波段的仙王座星盘角直径测量 显示英文标题

标题： CHARA Array K'-band Measurements of the Angular Dimensions of Be Star Disks

摘要： 我们展示了对北部Be星γ Cas、φ Per、ζ Tau和κ Dra首次进行的K'-波段、长基线干涉观测。 这些测量使用了CHARA阵列干涉仪的多个望远镜对，每次观测都表明目标恒星的周围星盘被解析。 我们用一个简单的盘模型预测来拟合干涉可见度，该模型假设气体处于开普勒旋转且温度恒定。 我们为每个目标推导出四个模型参数（盘底密度、径向密度指数、盘法线倾角和位置角）的拟合值。 由此得到的密度与之前关于红外过量流量的研究大致一致，而得到的方向通常与干涉H-α和连续极化观测的结果一致。 我们发现K'盘发射的角大小小于H-α发射确定的大小，并认为这种差异是由于H-α吸收率更大以及随着盘半径增加中性氢比例相对较大所致。 所有目标都是已知的双星系统，伴星较暗，我们发现伴星在φ Per和κ Dra的情况下似乎影响干涉可见度。 我们还提供了H-α、H-γ和Br-γ发射线的同时观测结果。 基于CHARA阵列观测得出的相同盘倾斜角和径向密度指数的合成模型谱线，在将盘底密度减少约1.7 dex时，与观测到的发射线强度相匹配。 显示英文摘要

摘要： We present the first K'-band, long-baseline interferometric observations of the northern Be stars gamma Cas, phi Per, zeta Tau, and kappa Dra. The measurements were made with multiple telescope pairs of the CHARA Array interferometer, and in every case the observations indicate that the circumstellar disks of the targets are resolved. We fit the interferometric visibilities with predictions from a simple disk model that assumes an isothermal gas in Keplerian rotation. We derive fits of the four model parameters (disk base density, radial density exponent, disk normal inclination, and position angle) for each of the targets. The resulting densities are in broad agreement with prior studies of the IR excess flux and the resulting orientations generally agree with those from interferometric H-alpha and continuum polarimetric observations. We find that the angular size of the K' disk emission is smaller than that determined for the H-alpha emission, and we argue that the difference is the result of a larger H-alpha opacity and the relatively larger neutral hydrogen fraction with increasing disk radius. All the targets are known binaries with faint companions, and we find that companions appear to influence the interferometric visibilities in the cases of phi Per and kappa Dra. We also present contemporaneous observations of the H-alpha, H-gamma, and Br-gamma emission lines. Synthetic model profiles of these lines that are based on the same disk inclination and radial density exponent as derived from the CHARA Array observations match the observed emission line strength if the disk base density is reduced by approximately 1.7 dex.