Be星FY Canis Majoris的热亚矮星伴星的探测
Detection of a Hot Subdwarf Companion to the Be Star FY Canis Majoris
摘要：
Be星的快速自转可能是由相互作用双星中过去的质量和角动量吸积引起的，其中质量供体目前被视为一个小的，热的亚矮星剥离了它的外壳。在这里，我们报告的光谱检测这样的亚矮星的Be二元系统FY大犬座从IUE航天器和KPNO Coude Feed望远镜在16年和21年的过程中获得的数据分析，分别。我们提出了一个双线光谱轨道的基础上的径向速度从IUE光谱和使用的轨道解与多普勒层析成像算法来重建组件的紫外光谱。次矮星温度很高（T_eff = 45+/-5 kK），质量约为1.3 M_sun，半径约为0.6 R_sun。它贡献的通量大约是Be星在FUV中的4%。我们还提出的H-α和He I 6678发射功能，形成在拱盘的Be星的观测。He I 6678的轨道通量和速度变化表明，大部分的排放形式沿盘边缘面临的热亚矮星的磁盘可能被加热的入射辐射从亚矮星。对1980年代发现的FUV落壳线的研究证实了它们的存在，但也揭示了它们往往在两个正交相位附近被发现，这与大陵五双星的模式不同。相依赖的变化，在UV N V的双重建议存在的N-增强风从亚矮星和可能的冲击之间的相互作用区域的恒星，亚矮星的风碰撞的磁盘的Be星。
英文摘要：
The rapid rotation of Be stars may be caused in some cases by past mass and angular momentum accretion in an interacting binary in which the mass donor is currently viewed as a small, hot subdwarf stripped of its outer envelope. Here we report on the spectroscopic detection of such a subdwarf in the Be binary system FY Canis Majoris from the analysis of data acquired by the IUE spacecraft and KPNO Coude Feed Telescope over the course of 16 and 21 years, respectively. We present a double-lined spectroscopic orbit for the binary based upon radial velocities from the IUE spectra and use the orbital solutions with a Doppler tomography algorithm to reconstruct the components' UV spectra. The subdwarf is hot (T_eff = 45+/-5 kK) and has a mass of about 1.3 M_sun and a radius of about 0.6 R_sun. It contributes about 4% as much flux as the Be star does in the FUV. We also present observations of the H-alpha and He I 6678 emission features that are formed in the circumstellar disk of the Be star. Orbital flux and velocity variations in the He I 6678 profile indicate that much of the emission forms along the disk rim facing the hot subdwarf where the disk is probably heated by the incident radiation from the subdwarf. A study of the FUV infall shell lines discovered in the 1980s confirms their episodic presence but reveals that they tend to be found around both quadrature phases, unlike the pattern in Algol binaries. Phase-dependent variations in the UV N V doublet suggest the presence of a N-enhanced wind from the subdwarf and a possible shock-interaction region between the stars where the subdwarf's wind collides with the disk of the Be star.
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