The magnetic field of the pre-main sequence Herbig Ae star HD 190073
The magnetic field of the pre-main sequence Herbig Ae star HD 190073
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前主序带 Herbig Ae 星 HD 190073 的磁场
DOI：
10.1051/0004-6361:20066264
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发表时间：
2006
影响因子：
6.5
通讯作者：
J. Silvester
中科院分区：
文献类型：
--
作者：
C. Català;E. Alecian;J. Donati;G. Wade;J. Landstreet;T. Böhm;J. Bouret;S. Bagnulo;C. Folsom;C. Folsom;J. Silvester;J. Silvester
本文的总体背景是研究主序前中等质量Herbig Ae/Be星的磁场。磁场可能在这些质量的主序前演化中发挥重要作用，特别是在控制恒星角动量的获得和损失方面。本文的主要目的是宣布在Herbig Ae星星HD 190073中探测到结构磁场，并讨论星星的几何形状、环境和磁场的各种解释。我们在2005年和2006年使用CFHT的ESPaDOnS分光偏振仪获得了高分辨率和信噪比的圆偏振光谱，这清楚地证明了该星星光球层中存在磁场。获得了九个圆偏振光谱，每个圆偏振光谱都显示出清晰的塞曼特征。这个特征暗示了一个大尺度的磁场结构。该特征对应于74+- 10 G的纵向磁场，在一年的时间范围内不会发生可检测的变化，表明旋转轴和视线之间的方位角对称场，零倾角，或非常长的旋转周期。HD 190073的光谱显示出大量的发射线。我们讨论了这些发射线的框架中的一个模型，涉及一个动荡的加热区域的基础上的恒星风，可能由磁吸积。这种磁性探测为我们理解中等质量恒星的磁性提供了重要的元素。
The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution and signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74+- 10 G, does not vary detectably on a one-year timeframe, indicating either an azimuthally symmetric field, a zero inclination angle between the rotation axis and the line of sight, or a very long rotation period. The optical spectrum of HD 190073 exhibits a large number of emission lines. We discuss the formation of these emission lines in the framework of a model involving a turbulent heated region at the base of the stellar wind, possibly powered by magnetic accretion. This magnetic detection brings an important element for our understanding of stellar magnetism at intermediate masses.