彗星科学。彗星 67P/楚留莫夫-格拉希门克的地下特性和早期活动。
Cometary science. Subsurface properties and early activity of comet 67P/Churyumov-Gerasimenko.
机构信息
Jet Propulsion Laboratory/California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.
LERMA, Observatoire de Paris, PSL Research University, UPMC Université Paris 06, CNRS, UMR8112, F-75014 Paris, France.
出版信息
Science. 2015 Jan 23;347(6220):aaa0709. doi: 10.1126/science.aaa0709.
Heat transport and ice sublimation in comets are interrelated processes reflecting properties acquired at the time of formation and during subsequent evolution. The Microwave Instrument on the Rosetta Orbiter (MIRO) acquired maps of the subsurface temperature of comet 67P/Churyumov-Gerasimenko, at 1.6 mm and 0.5 mm wavelengths, and spectra of water vapor. The total H2O production rate varied from 0.3 kg s(-1) in early June 2014 to 1.2 kg s(-1) in late August and showed periodic variations related to nucleus rotation and shape. Water outgassing was localized to the "neck" region of the comet. Subsurface temperatures showed seasonal and diurnal variations, which indicated that the submillimeter radiation originated at depths comparable to the diurnal thermal skin depth. A low thermal inertia (~10 to 50 J K(-1) m(-2) s(-0.5)), consistent with a thermally insulating powdered surface, is inferred.
彗星中的热输运和冰升华是相互关联的过程，反映了在形成时和随后的演化过程中获得的性质。罗塞塔轨道飞行器上的微波仪器（MIRO）在 1.6 毫米和 0.5 毫米波长处获取了彗星 67P/楚留莫夫-格拉希门克的地下温度图，并获取了水蒸气的光谱。总 H2O 生成速率在 2014 年 6 月初从 0.3 kg s(-1)变化到 8 月底的 1.2 kg s(-1)，并表现出与核旋转和形状有关的周期性变化。水汽逸出被局限在彗星的“颈部”区域。地下温度显示出季节性和昼夜变化，这表明亚毫米辐射源自与昼夜热皮肤深度相当的深度。推断出低热惯性（~10 至 50 J K(-1) m(-2) s(-0.5)），这与热绝缘的粉末状表面一致。
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