Hα spectropolarimetry of B[e] and Herbig Be stars
Hα spectropolarimetry of B[e] and Herbig Be stars
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B[e] 和 Herbig Be 星的 Hα 分光偏振法
DOI：
10.1046/j.1365-8711.1999.02383.x
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发表时间：
1999
影响因子：
4.8
通讯作者：
J. Drew
中科院分区：
文献类型：
--
作者：
R. Oudmaijer;J. Drew
本文给出了霍夫天体B（e）和Herbig Be天体的中分辨率（60 km/s 1）分光偏振观测结果.在大部分的物体中检测到了His线偏振的变化，其特征从Herbig Be星中的简单去偏振到可能的主序后B（e）星中的更复杂行为。在HD 37806和HD 50138的光谱中，每个都由一个双峰极化线和一个叠加的非极化单发射峰组成，表明两个不同的线形成区域。对HD 45677的多次观测首次将电子和尘埃散射效应分开：两个分量的固有偏振角之间的差异表明尘埃散射区域是cloudspectacular的。两个意想不到的结果是没有检测到的H极化的变化！Ori，其中去极化先前已被检测到，并在MWC 297，其中表现出在无线电波长源伸长。进去！猎户座的时间变化可能是负责，使这颗星星的电子散射盘是在观测时大大削弱。提出了两个可能解释MWC 297结果的假设。一般的发现是，大约有一半观测到的赫比格Be星显示出跨越H ε的偏振变化，这立即意味着它们的电离包络不是球对称的。这种模式，如果通过更大样本的观测得到证实，可能表明未检测率仅仅是随机取向的拱星盘采样的结果，这些盘能够在几个恒星半径内散射星光。被归类为B（e）星的恒星都显示出跨越H的惊人的偏振变化。每种情况下的细节是不同的，但被广泛接受的概念，密集的H β发射赤道盘周围的这些对象是支持的。
We present the results of medium resolution (�v� 60 km s 1 ) spectropolarimetric observations across Hof a sample of B(e) and Herbig Be objects. A change in linear polarization across His detected in a large fraction of the objects, with characteristics ranging from simple depolarization in a couple of Herbig Be stars, to more complex behaviour in the probable post main sequence B(e) stars. Hin the spectra of HD 37806 and HD 50138 each consist of a double-peaked polarized line and a superposed unpolarized single emission peak, suggesting two distinct line-forming regions. Multiple observations of HD 45677 allow for the separation of electron and dust scattering effects for the first time: the difference between derived intrinsic polarization angles of the two components indicate that the dust-scattering region is clumpy. Two unexpected results are the non-detections of Hpolarization changes in ! Ori, where depolarization has previously been detected, and in MWC 297, which exhibits source elongation at radio wavelengths. In ! Ori time variability is probably responsible such that this star's electron-scattering disk was much weakened at the time of observation. Two hypotheses are advanced that might explain the MWC 297 result. The general findings are that roughly half of the observed Herbig Be stars show polarization changes across H�, implying immediately that their ionized envelopes are not spherically symmetric. This pattern, if confirmed by observations of a larger sample, could indicate that the non-detection rate is simply a consequence of sampling randomly-oriented circumstellar disks able to scatter starlight within a few stellar radii. The stars classified as B(e) stars all show startling polarization changes across H�. The details in each case are different, but the widely accepted concept of dense H�-emitting equatorial disks around these objects is supported.