arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1104.4833astro-ph.SR
收藏

Chandra观测到的高对比度恒星耀斑综述

A Survey of High Contrast Stellar Flares Observed by Chandra

Jacqueline McCleary, Scott Wolk

摘要:

前主序星的X射线光变曲线可以显示出耀斑形式的变化,改变了基线特征活动水平;最大的X射线耀斑的特征是快速上升到特征计数率的10倍以上,然后是较慢的准指数衰减。对这些高对比度X射线耀斑的分析使得能够研究前主序星最内部的磁场。我们已经扫描了ANCHORS数据库的钱德拉观测的恒星形成区,以扩大研究耀斑事件的前主序星在天空覆盖范围和体积。在研究开始时,我们从ANCHORS中可获得的14,000颗不同年龄和质量的恒星中开发了30个高对比度耀斑样本。应用时间分辨光谱分析的方法,我们得到了这些明亮的高能耀斑的温度,限制磁场强度,和环的长度。耀斑分析的结果进行了比较,2 MASS和斯皮策数据可用于我们的样本中的恒星。我们发现,最长的耀斑环长度(几个恒星半径的顺序)只看到恒星的红外数据表明存在磁盘。这表明最长的耀斑可能一直延伸到盘。这种长耀斑往往比所研究的其他大耀斑更脆弱。一个广泛的环长度的观察,表明不同类型的耀斑可能会发生在盘状年轻恒星物体。

英文摘要:

The X-ray light curves of pre-main sequence stars can show variability in the form of flares altering a baseline characteristic activity level; the largest X-ray flares are characterized by a rapid rise to more than 10 times the characteristic count rate, followed by a slower quasi-exponential decay. Analysis of these high-contrast X-ray flares enables the study of the innermost magnetic fields of pre-main sequence stars. We have scanned the ANCHORS database of Chandra observations of star-forming regions to extend the study of flare events on pre-main sequence stars both in sky coverage and in volume. We developed a sample of 30 high-contrast flares out of the 14,000 stars of various ages and masses available in ANCHORS at the start of our study. Applying methods of time-resolved spectral analysis, we obtain the temperatures, confining magnetic field strengths, and loop lengths of these bright, energetic flares. The results of the flare analysis are compared to the 2MASS and Spitzer data available for the stars in our sample. We find that the longest flare loop lengths (of order several stellar radii) are only seen on stars whose IR data indicates the presence of disks. This suggests that the longest flares may stretch all the way to the disk. Such long flares tend to be more tenuous than the other large flares studied. A wide range of loop lengths are observed, indicating that different types of flares may occur on disked young stellar objects.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑