Active Asteroid P/2017 S5 (ATLAS)
Active Asteroid P/2017 S5 (ATLAS)
复制标题
活跃小行星 P/2017 S5 (ATLAS)
DOI：
10.3847/1538-3881/aaf563
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
S. Larson
中科院分区：
文献类型：
--
作者：
D. Jewitt;Yoonyoung Kim;J. Rajagopal;S. Ridgway;R. Kotulla;Wilson M. Liu;M. Mutchler;Jing Li;H. Weaver;S. Larson
对活动小行星P/2017 S5近日点附近的观测显示，大颗粒（102-104 μm）以0.2-2 m s- 1的速度喷射，估计质量损失率为几kg s- 1。质量损失的持续时间（持续超过150天）与升华起源是相容的，这意味着这个物体很可能是一颗含冰的主带彗星。暴露的水冰覆盖的平衡升华只有0.1平方公里可以匹配数据。近日点后一年的观测显示该天体处于非活动状态，由此我们推断出其核有效半径（反照率假定为0.06±0.02）。这种大小的天体的引力逃逸速度仅为~ 0.3 m s - 1，与推断出的尘埃喷射速度相当。时间序列光度法提供了快速旋转（光曲线周期1.4小时）的初步证据，这也可能在质量损失中起作用，如果这是真的，则可能是升华扭矩自旋上升的结果。P/2017 S5与分裂的活动小行星对P/2016 J1-A和J1-B在物理和轨道上都有相似之处，这三个物体都可能是碰撞产生的~ 7亿年前的Theobalda家族的成员。
Observations of active asteroid P/2017 S5 when near perihelion reveal the ejection of large (102–104 μm) particles at 0.2–2 m s−1 speeds, with estimated mass-loss rates of a few kg s−1. The protracted nature of the mass loss (continuous over ∼150 days) is compatible with a sublimation origin, meaning that this object is likely an ice-bearing main-belt comet. Equilibrium sublimation of exposed water ice covering as little as 0.1 km2 can match the data. Observations a year after perihelion show the object in an inactive state from which we deduce a nucleus effective radius (albedo 0.06 ± 0.02 assumed). The gravitational escape speed from a body of this size is just ∼0.3 m s−1, comparable to the inferred ejection speed of the dust. Time-series photometry provides tentative evidence for rapid rotation (lightcurve period 1.4 hr) that may also play a role in the loss of mass and which, if real, is a likely consequence of spin-up by sublimation torques. P/2017 S5 shares both physical and orbital similarities with the split active asteroid pair P/2016 J1-A and J1-B, and all three objects are likely members of the ∼7 Myr old, collisionally produced, Theobalda family.
影响因子：
5.3
作者：
Hsieh, Henry H.;Jewitt, David;Ishiguro, Masateru
通讯作者：
Ishiguro, Masateru
影响因子：
5.3
作者：
Blanton, Michael R.;Bershady, Matthew A.;Zou, Hu
通讯作者：
Zou, Hu