Spatial and diurnal variation of water outgassing on comet 67P/Churyumov-Gerasimenko observed from Rosetta/MIRO in August 2014
Spatial and diurnal variation of water outgassing on comet 67P/Churyumov-Gerasimenko observed from Rosetta/MIRO in August 2014
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DOI：
10.1051/0004-6361/201526155
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发表时间：
2015-11
影响因子：
6.5
通讯作者：
Seungwon Lee;P. V. Allmen;M. Allen;G. Beaudin;N. Biver;D. Bockelée-Morvan;M. Choukroun;J. Crovisier;P. Encrenaz;M. Frerking;S. Gulkis;P. Hartogh;M. Hofstadter;W. Ip;M. Janssen;C. Jarchow;S. Keihm;E. Lellouch;C. Leyrat;L. Rezac;F. Schloerb;T. Spilker;B. Gaskell;L. Jorda;H. Keller;H. Sierks
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文献类型：
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作者：
Seungwon Lee;P. V. Allmen;M. Allen;G. Beaudin;N. Biver;D. Bockelée-Morvan;M. Choukroun;J. Crovisier;P. Encrenaz;M. Frerking;S. Gulkis;P. Hartogh;M. Hofstadter;W. Ip;M. Janssen;C. Jarchow;S. Keihm;E. Lellouch;C. Leyrat;L. Rezac;F. Schloerb;T. Spilker;B. Gaskell;L. Jorda;H. Keller;H. Sierks
目标。我们提出了在彗星67 P/Churyumov-Gerasimenko使用（H2O）-O-16旋转过渡线在556.936 GHz的空间和日变化的水出气从Rosetta/MIRO在2014年8月。方法.水线分析与非LTE辐射传输模型和最佳估计方法来检索（H2O）-O-16放气强度，膨胀速度，和气体动力学温度。在2014年8月7日至9日和8月18日至19日，MIRO对围绕自旋轴旋转的原子核进行了长期稳定的天底指向观测。在观测期间，MIRO光束的地面轨迹主要位于67 P彗星的北方半球，覆盖了它的三个不同部分：所谓的头部，身体和颈部区域。结果MIRO光谱观测数据表明，水的放气强度在0.1 × 10 ~（25）molecules s ~（-1）sr ~（-1）sr）之间变化30倍，气体终端膨胀速度在0.61 ~ 0.78 km s ~（-1）之间变化0.17 km s ~（-1），终端气体温度在47 ~ 74 K之间变化27 K。检索到的彗差参数与当地的环境变量，如地下温度，测量的MIRO连续带，当地的太阳时，照明条件，和束在核上的位置共同注册。释气活动的空间变化非常明显，2014年8月最大的释气活动发生在核颈部附近。颈区的放气活动也与当地的太阳时有关，而当地的太阳时又与当地的光照条件有关。
Aims. We present the spatial and diurnal variation of water outgassing on comet 67P/Churyumov-Gerasimenko using the (H2O)-O-16 rotational transition line at 556.936 GHz observed from Rosetta/MIRO in August 2014. Methods. The water line was analyzed with a non-LTE radiative transfer model and an optimal estimation method to retrieve the (H2O)-O-16 outgassing intensity, expansion velocity, and gas kinetic temperature. On August 7-9, 2014 and August 18-19, 2014, MIRO performed long steady nadir-pointing observations of the nucleus while it was rotating around its spin axis. The ground track of the MIRO beam during the observation was mostly on the northern hemisphere of comet 67P, covering its three distinct parts: the so-called head, body, and neck areas. Results. The MIRO spectral observation data show that the water-outgassing intensity varies by a factor of 30, from 0.1 x 1025 molecules s(-1) sr l to 3.0 x 10(25) molecules s(-1) sr, the terminal gas expansion velocity varies by 0.17 km s(-1) from 0.61 km s(-1) to 0.78 km s(-1), and the terminal gas temperature varies by 27 K from 47 K to 74 K. The retrieved coma parameters are co-registered with local environment variables such as the subsurface temperatures, measured in the MIRO continuum bands, the local solar time, illumination condition, and beam location on nucleus. The spatial variation of the outgassing activity is very noticeable, and the largest outgassing activity in August 2014 occurs near the neck region of the nucleus. The outgassing activity in the neck region is also found to be correlated with the local solar hour, which is related to the local illumination condition.