Simultaneous Chandra and Very Large Array Observations of Young Stars and Protostars in ρ Ophiuchus Cloud Core A
Simultaneous Chandra and Very Large Array Observations of Young Stars and Protostars in ρ Ophiuchus Cloud Core A
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对 ρ 蛇夫座云核心 A 中年轻恒星和原恒星的钱德拉和甚大阵列同时观测
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发表时间：
2004
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通讯作者：
Kathryne J. Daniel
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作者：
M. Gagne;S. Skinner;Kathryne J. Daniel
钱德拉对蛇夫座ρ云核A的96 k x射线观测发现了87个源，其中60个与其他波长的对应源相对应。x射线探测包括14颗已知经典金牛座T星（CTTSs）中的12颗，17颗已知弱线T星（WTTSs）中的15颗，以及15颗褐矮星候选星中的4颗。x射线探测的特点是硬的、重吸收的发射。大多数x射线检测在AV≈10-20等范围内有视觉消光，但也检测到一些视觉吸收高达AV≈40-56等的源。一个典型源的平均光子能量⟨E⟩≈3 keV，并且超过一半的探测是可变的。在异常的近距离双星系统Oph S1、x射线明亮的WTTS DoAr 21和褐矮星候选星系GY 31 （M5.5）中发现了突出的x射线耀斑。DoAr 21耀斑的时间分辨光谱分析清楚地揭示了在衰变阶段可能重新加热等离子体的一系列次级耀斑。我们发现CTTSs和WTTSs的x射线光度分布和光谱硬度相似。我们还得出结论，探测到的褐矮星候选者的x射线发射比TTSs更弱，但光谱相似。同时多频甚大阵列（VLA）观测到31个6厘米的射电源，其中10个也被钱德拉探测到。我们报道了光学不可见的红外源WLY 2-11和微弱的Hα发射线星Elias 24 （II类）的新无线电探测。我们证实了Oph S1的圆偏振，并报道了DoAr 21中圆偏振的新检测。在钱德拉和VLA同时探测到的小样本tss中，我们没有发现x射线和射电亮度相关的证据。我们描述了一种新的非参数方法，用于估计从未分组光子事件表的x射线光谱性质，这是适用于微弱和明亮的x射线源。该方法用于生成fX、log T和LX光曲线。此外，我们还提供了一个公开可用的电子数据库，其中包含了a核心区域345个已知x射线、红外和射电源的多波长数据。
A 96 ks Chandra X-ray observation of ρ Ophiuchus cloud core A detected 87 sources, of which 60 were identified with counterparts at other wavelengths. The X-ray detections include 12 of 14 known classical T Tauri stars (CTTSs) in the field, 15 of 17 known weak-lined TTSs (WTTSs), and 4 of 15 brown dwarf candidates. The X-ray detections are characterized by hard, heavily absorbed emission. Most X-ray detections have visual extinctions in the range AV ≈ 10-20 mag, but several sources with visual absorptions as high as AV ≈ 40-56 mag were detected. The mean photon energy of a typical source is ⟨E⟩ ≈ 3 keV, and more than half of the detections are variable. Prominent X-ray flares were detected in the unusual close binary system Oph S1, the X-ray-bright WTTS DoAr 21, and the brown dwarf candidate GY 31 (M5.5). Time-resolved spectroscopic analysis of the DoAr 21 flare clearly reveals a sequence of secondary flares during the decay phase that may have reheated the plasma. We find that the X-ray luminosity distributions and spectral hardnesses of CTTSs and WTTSs are similar. We also conclude that the X-ray emission of detected brown dwarf candidates is less luminous than TTSs, but spectroscopically similar. Simultaneous multifrequency Very Large Array (VLA) observations detected 31 radio sources at 6 cm, of which 10 were also detected by Chandra. We report new radio detections of the optically invisible IR source WLY 2-11 and the faint Hα emission line star Elias 24 (class II). We confirm circular polarization in Oph S1 and report a new detection of circular polarization in DoAr 21. We find no evidence that X-ray and radio luminosities are correlated in the small sample of TTSs detected simultaneously with Chandra and the VLA. We describe a new nonparametric method for estimating X-ray spectral properties from unbinned photon event lists that is applicable to both faint and bright X-ray sources. The method is used to generate fX, log T, and LX light curves. In addition, we provide a publicly available electronic database containing multiwavelength data for 345 known X-ray, IR, and radio sources in the core A region.