论文标题
来自潮汐同步二进制的非常缓慢的旋转器
Very Slow Rotators from Tidally Synchronized Binaries
论文作者
论文摘要
最近对K2 Lightcurves的检查表明，约有15％的木星木马的旋转速度非常缓慢（旋转周期ps> 100 h）。在这里，我们考虑了这些物体在〜20-30 au的大磁盘中形成相等大小的二进制文件的可能性。在将其植入为木星木马之前，紧密的二进制文件潮汐朝向具有PS〜Pb的同步状态，其中Pb是二元轨道时期。随后，它们可能被撞击和行星相遇所解散，至少一个二元组件保留了缓慢的旋转。在潮流轨道上存活的二进制室将继续通过潮汐和4.5 Gyr的自旋变化影响而发展。为了解释观察到的缓慢旋转器的比例，我们发现至少约15-20％的外部磁盘具有直径15 <d <50 km的外部磁盘体，必须以12 <ab/r <30的相等大小的二进制形式形成，其中ab是二进制半轴轴和r = d/2。这里提出的机制还可以解释其他小体小种群中发现的非常缓慢的旋转器。
A recent examination of K2 lightcurves indicates that ~15% of Jupiter Trojans have very slow rotation (spin periods Ps>100 h). Here we consider the possibility that these bodies formed as equal-size binaries in the massive outer disk at ~20-30 au. Prior to their implantation as Jupiter Trojans, tight binaries tidally evolved toward a synchronous state with Ps~Pb, where Pb is the binary orbit period. They may have been subsequently dissociated by impacts and planetary encounters with at least one binary component retaining its slow rotation. Surviving binaries on Trojan orbits would continue to evolve by tides and spin-changing impacts over 4.5 Gyr. To explain the observed fraction of slow rotators, we find that at least ~15-20% of outer disk bodies with diameters 15<D<50 km would have to form as equal-size binaries with 12<ab/R<30, where ab is the binary semimajor axis and R=D/2. The mechanism proposed here could also explain very slow rotators found in other small body populations.
