A Universal Spin–Mass Relation for Brown Dwarfs and Planets
A Universal Spin–Mass Relation for Brown Dwarfs and Planets
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褐矮星和行星的通用自旋质量关系
DOI：
10.3847/1538-4357/aabfbe
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
B. Stelzer
中科院分区：
文献类型：
--
作者：
A. Scholz;Keavin Moore;R. Jayawardhana;S. Aigrain;D. Peterson;B. Stelzer
虽然褐矮星在其生命的早期表现出与恒星的相似性，但它们的自旋演化更类似于行星。我们利用K2使命的光变曲线测量了金牛座恒星形成区18颗年轻棕矮星的新自转周期。我们的样品跨越质量从0.02到0.08 M Ω，并已在过去广泛的特点。为了搜索周期，我们利用三种不同的方法（自相关，周期图，高斯过程）。有圆盘的棕矮星的中位周期是没有圆盘的棕矮星的两倍（3.1天对1.6天），这是圆盘旋转制动的标志，尽管数字很小。金牛座中的棕矮星的整体平均周期为1.9天，其自转速度比在较老（3-10百万年）的恒星形成区中的棕矮星慢，这与后者由于收缩和角动量守恒而自旋上升相一致，这清楚地表明在这个质量域中，盘制动整体上是低效和/或暂时的。我们确认存在的典型的旋转周期作为质量的函数在亚恒星政权的线性增加。假设角动量守恒，旋转速度向前计算到太阳系的年龄时，符合太阳系行星和太阳系外行星质量物体的已知自旋质量关系。这种自旋质量趋势在质量上超过六个数量级，包括来自几个不同形成路径的物体。我们的结果意味着褐矮星在其演化的最初几个百万年中基本上保持了它们的原始角动量。
While brown dwarfs show similarities to stars early in their lives, their spin evolutions are much more akin to those of planets. We have used light curves from the K2 mission to measure new rotation periods for 18 young brown dwarfs in the Taurus star-forming region. Our sample spans masses from 0.02 to 0.08 M⊙ and has been characterized extensively in the past. To search for periods, we utilize three different methods (autocorrelation, periodogram, Gaussian processes). The median period for brown dwarfs with disks is twice as long as for those without (3.1 versus 1.6 days), a signature of rotational braking by the disk, albeit with small numbers. With an overall median period of 1.9 days, brown dwarfs in Taurus rotate slower than their counterparts in somewhat older (3–10 Myr) star-forming regions, consistent with spin-up of the latter due to contraction and angular momentum conservation, a clear sign that disk braking overall is inefficient and/or temporary in this mass domain. We confirm the presence of a linear increase of the typical rotation period as a function of mass in the substellar regime. The rotational velocities, when calculated forward to the age of the solar system, assuming angular momentum conservation, fit the known spin–mass relation for solar system planets and extra-solar planetary-mass objects. This spin–mass trend holds over six orders of magnitude in mass, including objects from several different formation paths. Our result implies that brown dwarfs by and large retain their primordial angular momentum through the first few Myr of their evolution.
影响因子：
4.8
作者：
H. Giles;A. Cameron;R. Haywood
通讯作者：
H. Giles;A. Cameron;R. Haywood
影响因子：
6.5
作者：
Baraffe, Isabelle;Homeier, Derek;Chabrier, Gilles
通讯作者：
Chabrier, Gilles