Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco
Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco
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上层斯科快速旋转低质量 WTT 的开普勒同转半径处的物质轨道云
DOI：
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
M. Pinsonneault
中科院分区：
文献类型：
--
作者：
J. Stauffer;A. Cameron;M. Jardine;T. David;L. Rebull;A. Cody;L. Hillenbrand;D. Barrado;S. Wolk;J. Davenport;M. Pinsonneault
使用K2数据，我们确定了ρ Oph和上天蝎座恒星形成区的23个非常低质量的成员，这些成员具有周期性的光度变化，这些变化不容易用星星斑点、食双星或脉动等公认的物理机制来解释。所有这些不寻常的恒星都是M型中晚期矮星，没有活跃吸积的证据，光度周期一般小于1天。通常，不寻常的光变曲线特征表现为狭窄的通量下降;当我们也有来自星星斑点的旋转周期时，两个周期一致，这表明通量下降是由于物质以开普勒共同旋转半径围绕星星旋转。我们有时会在相位光变曲线形态中看到“状态变化”，其中25%的波形在不到一天的时间尺度上改变形状;通常，“状态变化”发生在强烈耀斑之后。对于具有这些突然的光变曲线形态变化的恒星群，我们认为它们的通量下降最有可能是由暖日冕气体云的食引起的，类似于用来解释剑鱼座AB和其他快速旋转的晚型恒星中瞬态Hα吸收特征的弹弓双折射。对于另一组恒星的周期稍长，我们发现短持续时间的流量骤降是高度可变的短期和长期的时间尺度，一般不对称的流量骤降配置文件。我们相信，这些通量下降是由于微粒云可能与一个接近的行星或由最近的碰撞事件造成的。
Using K2 data, we identified 23 very-low-mass members of the ρ Oph and Upper Scorpius star-forming region as having periodic photometric variability not easily explained by well-established physical mechanisms such as star spots, eclipsing binaries, or pulsation. All of these unusual stars are mid-to-late M dwarfs without evidence of active accretion, and with photometric periods generally <1 day. Often the unusual light-curve signature takes the form of narrow flux dips; when we also have rotation periods from star spots, the two periods agree, suggesting that the flux dips are due to material orbiting the star at the Keplerian co-rotation radius. We sometimes see “state-changes” in the phased light-curve morphologies where ∼25% of the waveform changes shape on timescales less than a day; often, the “state-change” takes place immediately after a strong flare. For the group of stars with these sudden light-curve morphology shifts, we attribute their flux dips as most probably arising from eclipses of warm coronal gas clouds, analagous to the slingshot prominences postulated to explain transient Hα absorption features in AB Doradus and other rapidly rotating late-type stars. For another group of stars with somewhat longer periods, we find the short-duration flux dips to be highly variable on both short and long timescales, with generally asymmetric flux-dip profiles. We believe that these flux dips are due to particulate clouds possibly associated with a close-in planet or resulting from a recent collisional event.
斯隆数字巡天第十次数据发布：来自 SDSS-III 阿帕奇点天文台银河演化实验的首个光谱数据
DOI：
10.1088/0067-0049/211/2/17
发表时间：
2014
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
Ahn C
通讯作者：
Ahn C
影响因子：
6.5
作者：
Baraffe, Isabelle;Homeier, Derek;Chabrier, Gilles
通讯作者：
Chabrier, Gilles