Methane and its isotopologues on Saturn from Cassini/CIRS observations
Methane and its isotopologues on Saturn from Cassini/CIRS observations
复制标题
DOI：
10.1016/j.icarus.2008.09.019
复制
发表时间：
2009-02-01
期刊：
影响因子：
3.2
通讯作者：
Bjoraker, G. L.
中科院分区：
文献类型：
--
作者：
Fletcher, L. N.;Orton, G. S.;Bjoraker, G. L.
卡西尼复合红外光谱仪的高光谱分辨率观测[Flasar，F.M.，和44位同事，2004年。空间科学Rev. 115，169-297]中的CH（4）、CH（3）D和（13）CH（4）的摩尔分数的新估计值。（4.7 +/- 0.2）x 10（-3），（3.0 ± 0.2）× 10 ~（-7）和（5.1 ± 0.2）× 10 ~（-5）。该分析结合了远红外甲烷旋转线和甲烷及其同位素的中红外特征的数据，使用[欧文等人]的相关k反演算法。[欧文，P.，2008年9名同事。J. Quant。光谱分析Radiat. 109，1136-1150]和逐行的方法来评估检索的数量的可靠性。发现C/H比Grevesse等人[Grevesse，N.，Asplund，M.，Sauval，A.，2007.空间科学Rev. 130（1），105-114]，比木星上的浓缩大2.25 +/- 0.55倍，并支持行星形成的核心吸积模型预测的核心质量分数随着与太阳的距离而增加。木星和土星的C/N，C/S和C/P比的比较表明，在一个原始的太阳星云，其组成随距离太阳不同的被困挥发物的不同水库。这得到了我们推导出的甲烷中D/H比（1.6 +/-0.2）× 10（-5）的支持，该比值似乎小于Lellouch等人的木星值[Lellouch，E.，Bezard，B.，Fouchet，T.，Feuchtgruber，H.，Encrenaz，T.，de Graauw，T.，2001.太空人。太空人。370，610-622]。中红外辐射特征提供了（12）C/（13）C = 91.8（7.8）（+8.4）的估计值，这与地球和木星的比率一致，表明碳是从所有行星的共享储存库中积累的。(c)2008年爱思唯尔公司All rights reserved.
High spectral resolution observations from the Cassini Composite Infrared Spectrometer [Flasar, F.M., and 44 colleagues, 2004. Space Sci. Rev. 115, 169-297] are analysed to derive new estimates for the mole fractions of CH(4), CH(3)D and (13)CH(4) of (4.7 +/- 0.2) x 10(-3), (3.0 +/- 0.2) x 10(-7) and (5.1 +/- 0.2) x 10-5 respectively, The mole fractions show no hemispherical asymmetries or latitudinal variability. The analysis combines data from the far-IR methane rotational lines and the mid-IR features of methane and its isotopologues, using both the correlated-k retrieval algorithm of [Irwin et a]. [Irwin, P., and 9 colleagues, 2008. J. Quant. Spectrosc. Radiat. Trans. 109, 1136-1150] and a line-by-line approach to evaluate the reliability of the retrieved quantities. C/H was found to be enhanced by 10.9 +/- 0.5 times the solar composition of Grevesse et al. [Grevesse, N., Asplund, M., Sauval, A., 2007. Space Sci. Rev. 130 (1), 105-114], 2.25 +/- 0.55 times larger than the enrichment on Jupiter, and supporting the increasing fractional core mass with distance from the Sun predicted by the core accretion model of planetary formation. A comparison of the jovian and saturnian C/N, C/S and C/P ratios suggests different reservoirs of the trapped volatiles in a primordial solar nebula whose composition varies with distance from the Sun. This is supported by our derived D/H ratio in methane of (1.6 +/- 0.2) x 10(-5), which appears to be smaller than the jovian value of Lellouch et al. [Lellouch, E., Bezard, B., Fouchet, T., Feuchtgruber, H., Encrenaz, T., de Graauw, T., 2001. Astron. Astrophys. 370, 610-622]. Mid-IR emission features provided an estimate of (12)C/(13)C = 91.8(7.8)(+8.4), which is consistent with both the terrestrial ratio and jovian ratio, suggesting that carbon was accreted from a shared reservoir for all of the planets. (c) 2008 Elsevier Inc. All rights reserved.