Be星的性质和性质：27。昴星团Be星Pleione = BU Tauri的轨道和近期长期变化
Properties and nature of Be stars: 27. Orbital and recent long-term variations of the Pleiades Be star Pleione = BU Tauri
摘要：
在H-α线的陡翼上测量的H-α辐射的径向速度变化，由于长时间的变化而被预白化，以（218.025 +/- 0.022）d的周期性变化，证实了明亮的Be星Pleione的怀疑的双星性质，Pleione是昴星团的成员。轨道似乎有一个高偏心率超过0.7，但我们也简要讨论的可能性，真正的轨道是圆形的，偏心率是虚假的，由于相位相关的影响，拱星物质。光谱轨道的投影角间距足够大，允许用大型光学干涉仪检测双星，前提是主次星等差不是太大。由于我们的数据涵盖了一个新的壳相的开始，发展的金属壳光谱，我们也简要地讨论了最近的长期变化。我们确认形成一个新的信封，与前一个共存，在发病的新壳相。我们发现，H-α分布的半高全宽随着时间的推移而减小。在这方面，我们简要地讨论了平田的进动气体盘的假设和可能的替代方案所观察到的长期变化。
英文摘要：
Radial-velocity variations of the H-alpha emission measured on the steep wings of the H-alpha line, prewhitened for the long-time changes, vary periodically with a period of (218.025 +/- 0.022)d, confirming the suspected binary nature of the bright Be star Pleione, a member of the Pleiades cluster. The orbit seems to have a high eccentricity over 0.7, but we also briefly discuss the possibility that the true orbit is circular and that the eccentricity is spurious owing to the phase-dependent effects of the circumstellar matter. The projected angular separation of the spectroscopic orbit is large enough to allow the detection of the binary with large optical interferometers, provided the magnitude difference primary - secondary is not too large. Since our data cover the onset of a new shell phase up to development of a metallic shell spectrum, we also briefly discuss the recent long-term changes. We confirm the formation of a new envelope, coexisting with the previous one, at the onset of the new shell phase. We find that the full width at half maximum of the H-alpha profile has been decreasing with time for both envelopes. In this connection, we briefly discuss Hirata's hypothesis of precessing gaseous disk and possible alternative scenarios of the observed long-term changes.
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