Rotational Modulation of M/L Dwarfs due to Magnetic Spots
Rotational Modulation of M/L Dwarfs due to Magnetic Spots
复制标题
磁斑引起的 M/L 矮星的旋转调制
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
A. Golden
中科院分区：
文献类型：
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作者：
C. Lane;G. Hallinan;R. Zavala;Raymond F. Butler;R. Boyle;S. Bourke;A. Antonova;J. G. Doyle;F. Vrba;A. Golden
我们发现在M/L矮星边界两侧的两个超低温矮星TVLM 513-46546和2MASS J00361617+1821104中存在周期性的i波段变化。这两个目标都是短周期射电瞬变，探测到的i波段周期与射电波长相匹配（TVLM 513-46546的P = 1.96小时，2MASS J00361617+1821104的P = 3小时）。我们将探测到的i波段周期性归因于矮星的旋转周期，并得到了半径估计和测量的v sin i值的支持。基于探测到的TVLM 513-46546 （M9）在I波段的旋转周期，以及最近射电观测中对强磁场的证实，我们认为磁致斑是这种周期性变化的原因。L3.5矮星2MASS J00361617+1821104的i波段旋转调制幅度随时间变化。我们得出结论，这个天体的i波段变化最可能的原因是磁斑，可能与时间演变的特征（如尘埃云）相结合。
We find periodic I-band variability in two ultracool dwarfs, TVLM 513-46546 and 2MASS J00361617+1821104, on either side of the M/L dwarf boundary. Both of these targets are short-period radio transients, with the detected I-band periods matching those found at radio wavelengths (P = 1.96 hr for TVLM 513-46546 and P = 3 hr for 2MASS J00361617+1821104). We attribute the detected I-band periodicities to the periods of rotation of the dwarfs, supported by radius estimates and measured v sin i values for the objects. Based on the detected period of rotation of TVLM 513-46546 (M9) in the I band, along with confirmation of strong magnetic fields from recent radio observations, we argue for magnetically induced spots as the cause of this periodic variability. The I-band rotational modulation of the L3.5 dwarf 2MASS J00361617+1821104 appeared to vary in amplitude with time. We conclude that the most likely cause of the I-band variability for this object is magnetic spots, possibly coupled with time-evolving features such as dust clouds.