地球物理和天体物理流体力学系列讲座

 

 

报告题目：Latest astrometric results for the Saturnian system

报告人：Valery Lainey 研究员 (巴黎天文台)

报告地点: 三楼大会议室

报告时间：2024年 6 月 11 日2024-06-11（周二） 上午9:30

腾讯会议: 677-120-308

报告摘要：

 During the thirteen years spent in orbit around Saturn before its final plunge, the Cassini probe provided more than ten thousand astrometric observations of moons. Such a large amount of precise data has allowed us to search for extremely small signals in the orbital motion of the Saturnian satellites. These signals can be linked to key physical mechanisms at play in the system, opening the doors to a new vision of the Saturn system. Using more than a century of ground-based astrometric observations, and benefiting from Cassini imaging data, we have studied the orbital motion of all of Saturn's inner and main moons, including those recently discovered by the Cassini probe. We show how astrometry has allowed us to characterize the strong tidal effects acting among the Saturnian system, while assessing the interior characteristics of several moons and their primary, including the discovery of Mimas' ocean. Updated results are presented.

 

报告人简介：

Dr. Lainey is an astronomer at the Paris observatory and an expert in orbital dynamics of Solar system objects.  His first research topic was the Galilean satellites, for which he showed that Io was close to thermal equilibrium.  Then he lead the team that discovered the significance of tidal dissipation within Saturn and more recently the existence of the Mimas’ ocean.  During the years 2017-2019 he participated to the end of the Cassini mission at JPL (NASA).

 

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报告题目：Dynamic of the system Pluto-Charon : determination of commensurabilities

报告人：Alain Vienne 教授 (巴黎天文台，里尔大学)

报告地点: 三楼大会议室

报告时间：2024年6 月 11 日（周二）上午 10:30

腾讯会议: 535-402-506

报告摘要：

The Pluto-Charon system is a binary system, characterised by its high mass ratio and its tidally locked synchronous orbit. Surrounding the central binary, four satellites - Styx, Nix, Kerberos and Hydra - follow near-circular and near equatorial orbits. Several studies have pointed out some commensurabilities, sometimes using the fast Fourier transform technique. We intend to precisely identify the commensurabilities between the Pluto-Charon satellites, using the tool of fine frequency analysis. We successfully identified all fundamental frequencies of the system. We highlight commensurabilities previously reported and introduce novel ones.

报告人简介：

Alain Vienne is a full professor at Paris observatory and Lille University. His fields of research are : orbital dynamics of natural satellites, dynamical planetology, astrometry, ephemerides. He was advisor of 11 PhD thesis. He is well-known for their analytical representations of the motion of the majors satellites of Jupiter and Saturn. These analytical representations allow him to lead theoretical studies on some specific resonances or commensurabilities : inclination type resonance of Mimas-Tethys, the De Haerdtl inequality between Ganymede and Calisto, the long-term evolution of the Jovian irregular satellites, the Titan 5:1 MMR with Iapetus, ... He also participates to the reduction of astrometric observations of the corresponding objects.

 

 

 

 

http://www.ucar.shao.cas.cn/ppm/report/202405/t20240531_787100.html

 

 

http://www.ucar.shao.cas.cn/ppm/report/202406/t20240601_787113.html