We calculate the minimum mass of heavy elements required in the envelopes of Jupiter and Saturn to match the observed oversolar abundances of volatiles. Because the clathration efficiency remains unknown in the solar nebula, we have considered a set of sequences of ice formation in which the fraction of water available for clathration is varied between 0 and 100 %. In all the cases considered, we assume that the water abundance remains homogeneous whatever the heliocentric distance in the nebula and directly derives from a gas phase of solar composition. Planetesimals then form in the feeding zones of Jupiter and Saturn from the agglomeration of clathrates and pure condensates in proportions fixed by the clathration efficiency. A fraction of Kr and Xe may have been sequestrated by the H3+ ion in the form of stable XeH3+ and KrH3+ complexes in the solar nebula gas phase, thus implying the formation of at least partly Xe- and Kr-impoverished planetesimals in the feeding zones of Jupiter and Saturn. These planetesimals were subsequently accreted and vaporized into the hydrogen envelopes of Jupiter and Saturn, thus engendering volatiles enrichments in their atmospheres, with respect to hydrogen. Taking into account both refractory and volatile components, and assuming plausible molecular mixing ratios in the gas phase of the outer solar nebula, we show that it is possible to match the observed enrichments in Jupiter and Saturn, whatever the clathration efficiency. Our calculations predict that the O/H enrichment decreases from 6.7 to 5.6 times solar (O/H) in the envelope of Jupiter and from 18.1 to 15.4 times solar (O/H) in the envelope of Saturn with the growing clathration efficiency in the solar nebula.
Near-Infrared Photometry of Irregular Satellites of Jupiter and Saturn
本文介绍了10颗木星和4颗土星不规则卫星的JHK测光，这些卫星是在夏威夷莫纳克亚山的8米双子座北天文台用近红外成像仪（NIRI）拍摄的。观测到的天体具有与C、P和D型小行星一致的近红外颜色，尽管J XII Ananke和S IX Phoebe在H滤波器中显示出微弱的可能水特征。Himalia家族的四个成员具有相似的近红外颜色，高卢家族的两个成员S XX Paaliaq和S XXIX Siarnaq也是如此。根据基于宽带颜色和覆盖0.4至2.2微米的低分辨率归一化反射光谱，不规则卫星被确定为C型（J VII Pasiphae，J VI Himalia和S IX Phoebe），P型（J XII Ananke和J XVIII Themisto）和D型（J IX Carme和J X Sinope），显示出这些物体的起源多样性。
Jupiter, Saturn and the Pioneer anomaly: a planetary-based independent test
在本文中，我们使用对木星和土星近日点的标准牛顿/爱因斯坦长期岁差的修正比率，最近由俄罗斯天文学家E. V. Pitjeva通过将近一个世纪的数据与天文历表拟合来估计，对先锋异常（PA）的假设进行独立的，基于行星的测试，因为它目前已知在5-10 AU区域，是引力的起源考虑到确定的拱线额外率和木星和土星轨道上PA加速度值的误差，答案是否定的。如果对整个先锋10/11的重新分析完成，就可以得出更确切的结论。此外，其他天文学家团队独立估计他们自己对近日点岁差的修正也很重要。
