Spots, Flares, Accretion, and Obscuration in the Pre-main-sequence Binary DQ Tau
Spots, Flares, Accretion, and Obscuration in the Pre-main-sequence Binary DQ Tau
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前主序二元 DQ Tau 中的斑点、耀斑、吸积和遮蔽
DOI：
10.3847/1538-4357/aacafa
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
A. P'al
中科院分区：
文献类型：
--
作者：
Á. Kóspál;P. 'Abrah'am;G. Zsidi;K. Vida;R. Szab'o;A. Mo'or;A. P'al
DQ Tau是一个年轻的低质谱双星，由两颗质量几乎相等的恒星组成，周期为15.8天，周围环绕着一个环双星盘。在这里，我们分析了由开普勒K2、斯皮策太空望远镜和地面设施获得的DQ Tau的光曲线。我们观察到变异性现象，包括恒星黑子的旋转调制，恒星耀斑引起的短暂增亮事件，由于吸积增加引起的长时间增亮事件，以及由于短暂的星周遮挡引起的短下降。旋转调制呈正弦变化，周期为3.017天。在我们的模型中，这是由于延伸的恒星黑子比恒星有效温度低400 K造成的。在我们长达80天的监测中，我们检测到40个能量高达1.2 × 1035 erg的恒星耀斑，持续时间为几个小时。耀斑的轮廓与较老的晚型恒星非常相似，它们的出现与旋转周期或轨道周期都无关。我们观察到每颗星周围的吸积速率高达5 × 10−8 M⊙yr−1。我们的斯皮策数据表明，增加的吸积光度暂时使环双星盘的内部温度升高了约100k。我们发现内盘半径为0.13 au，明显小于环双星盘动力学建模的预期。有趣的是，圆盘的内缘与双星的轨道重合。DQ Tau在其光曲线上也显示出小于0.1等的短倾角，这让人想起了在许多低质量年轻恒星中观察到的著名的“北斗七星现象”。
DQ Tau is a young low-mass spectroscopic binary, consisting of two almost equal-mass stars on a 15.8 day period surrounded by a circumbinary disk. Here, we analyze DQ Tau’s light curves obtained by Kepler K2, the Spitzer Space Telescope, and ground-based facilities. We observed variability phenomena, including rotational modulation by stellar spots, brief brightening events due to stellar flares, long brightening events around periastron due to increased accretion, and short dips due to brief circumstellar obscuration. The rotational modulation appears as a sinusoidal variation with a period of 3.017 days. In our model, this is caused by extended stellar spots 400 K colder than the stellar effective temperature. During our 80 day long monitoring, we detected 40 stellar flares with energies up to 1.2 × 1035 erg and duration of a few hours. The flare profiles closely resemble those in older late-type stars, and their occurrence does not correlate with either the rotational or the orbital period. We observe elevated accretion rates of up to 5 × 10−8 M⊙ yr−1 around each periastron. Our Spitzer data suggest that the increased accretion luminosity temporarily heats up the inner part of the circumbinary disk by about 100 K. We found an inner disk radius of 0.13 au, significantly smaller than expected from dynamical modeling of circumbinary disks. Interestingly, the inner edge of the disk corotates with the binary’s orbit. DQ Tau also shows short dips of <0.1 mag in its light curve, reminiscent of the well-known “dipper phenomenon” observed in many low-mass young stars.
适合 VLTI 观测的前主序谱双星，
影响因子：
6.5
作者：
Guenther;Esposito;Covino;Alcalá;Cusano;Stecklum
通讯作者：
Stecklum