所属 京都産業大学 理学部 宇宙物理・気象学科 職種 教授
|標題||New measurements of D/H on Mars using EXES aboard SOFIA|
|掲載誌名||Astronomy & Astrophysics|
|著者・共著者||Encrenaz, T.,DeWitt, C.,Richter, M. J.,Greathouse, T. K.,Fouchet, T.,Montmessin, F.,Lefèvre, F.,Bézard, B.,Atreya, S. K.,Aoki, S.,Sagawa, H.|
|概要||The global D/H ratio on Mars is an important measurement for understanding the past history of water on Mars
locally, through condensation and sublimation processes, it is a possible tracer of the sources and sinks of water vapor on Mars. Measuring D/H as a function of longitude, latitude and season is necessary for determining the present averaged value of D/H on Mars. Following an earlier measurement in April 2014, we used the Echelon Cross Echelle Spectrograph (EXES) instrument on board the Stratospheric Observatory for Infrared Astronomy (SOFIA) facility to map D/H on Mars on two occasions, on March 24, 2016 (Ls = 127°), and January 24, 2017 (Ls = 304°), by measuring simultaneously the abundances of H2O and HDO in the 1383-1391 cm-1 range (7.2 μm). The D/H disk-integrated values are 4.0 (+0.8, -0.6) × Vienna Standard Mean Ocean Water (VSMOW) and 4.5 (+0.7, -0.6) × VSMOW, respectively, in agreement with our earlier result. The main result of this study is that there is no evidence of strong local variations in the D/H ratio nor for seasonal variations in the global D/H ratio between northern summer and southern summer.