标题： 天船座新磁场测量的β星和慢脉动B星 显示英文标题

标题： New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars

摘要： 我们展示了使用甚大望远镜（VLT）上的FORS1继续进行的对我们所选样本的磁场测量结果，该样本由被确认或候选的β Cephei星和慢速脉动B型（以下简称SPB）星组成，同时包括少量正常的B型星。 在三颗已确认的β Cephei星以及两颗疑似β Cephei星中检测到了大约几百高斯量级的微弱平均纵向磁场；在五颗SPB星及八颗疑似SPB星中也发现了类似的磁场。 此外，在两颗正常B型星中诊断出超过3σ水平的纵向磁场：富氮早期B型星HD52089和B5 IV型星HD153716。 大约三分之一的β Cephei星拥有检测到的磁场：在迄今为止用FORS1研究的13颗β Cephei星中，有四颗星具有较弱的磁场；而在六颗疑似β Cephei星中，有两颗显示出较弱的磁场。 SPB星及其候选者的磁性比例更高：在34颗SPB星中约有一半被发现具有磁场，而在16颗候选SPB星中，有八颗星拥有磁场。 为了理解为何只有部分脉动星表现出磁场，我们研究了磁场脉动星与非磁场脉动星在赫罗图中的位置。 我们发现它们在赫罗图中的区域大部分重叠，并未清楚地显示出主序星上磁场演化的可能模式。 可能较强磁场更倾向于出现在具有较低脉动频率和较小脉动振幅的恒星中。 如果考虑磁场强度与v sin i值之间的相关性，也会发现类似的趋势，即较强的磁场更可能出现在旋转较慢的恒星中。 显示英文摘要

摘要： We present the results of the continuation of our magnetic survey with FORS1 at the VLT of a sample of B-type stars consisting of confirmed or candidate beta Cephei stars and Slowly Pulsating B (hereafter SPB) stars, along with a small number of normal B-type stars. A weak mean longitudinal magnetic field of the order of a few hundred Gauss was detected in three beta Cephei stars and two stars suspected to be beta Cephei stars, in five SPB stars and eight stars suspected to be SPB stars. Additionally, a longitudinal magnetic field at a level larger than 3sigma has been diagnosed in two normal B-type stars, the nitrogen-rich early B-type star HD52089 and in the B5 IV star HD153716. Roughly one third of beta Cephei stars have detected magnetic fields: Out of 13 beta Cephei stars studied to date with FORS1, four stars possess weak magnetic fields, and out of the sample of six suspected beta Cephei stars two show a weak magnetic field. The fraction of magnetic SPBs and candidate SPBs is found to be higher: roughly half of the 34 SPB stars have been found to be magnetic and among the 16 candidate SPBs eight stars possess magnetic fields. In an attempt to understand why only a fraction of pulsating stars exhibit magnetic fields, we studied the position of magnetic and non-magnetic pulsating stars in the H-R diagram. We find that their domains in the H-R diagram largely overlap, and no clear picture emerges as to the possible evolution of the magnetic field across the main sequence. It is possible that stronger fields tend to be found in stars with lower pulsating frequencies and smaller pulsating amplitudes. A somewhat similar trend is found if we consider a correlation between the field strength and the v sin i-values, i.e. stronger magnetic fields tend to be found in more slowly rotating stars.