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Magnetospheric Particle Precipitation at Titan


Nov. 22, 2019, 3:30 p.m. - 5 p.m.
Geology 6704

Presented By:
Emilie Royer
Planetary Science Institute

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The Cassini spacecraft observed Titan’s upper atmosphere and its airglow from 2005 to 2017 and in the past decade, results from the Cassini-Ultraviolet Imaging Spectrograph (UVIS) instrument greatly improved our understanding of airglow production at Titan. However, combining remote-sensing datasets, such as Cassini-UVIS data, with in-situ measurements taken by the Cassini Plasma Spectrometer (CAPS) instrument can provide us with a more rigorous assessment of the airglow contribution. It is now established that the solar XUV radiation is the main source of dayglow, while magnetospheric particle precipitation principally acts on the nightside of the satellite. One of the questions that might stay unanswered after the end of the Cassini mission concerns the role and quantification of the magnetospheric particle precipitation and other minor sources such as micrometeorite precipitation and/or cosmic galactic ray at Titan. In this presentation, I will be reporting on Ultraviolet (UV) observations of Titan airglow enhancements correlated with magnetospheric changing conditions occurring while the spacecraft, and thus Titan, are known to have crossed Saturn’s magnetopause and have been exposed to the magnetosheath environment. In addition, the processing and interpretation of 13+ years of airglow observations at Titan allows now for detail studies of the upper atmosphere as a function of the Saturn Local Time (SLT) and the solar cycle. UVIS observations of Titan around 12PM SLT (near Saturn’s magnetopause) present evidence of Titan’s upper atmosphere response to a fluctuating magnetospheric environment. Correlations between data from simultaneous observations of in-situ Cassini instruments (CAPS, RPWS and MIMI) has been possible on few occasions and events such as electron burst and reconnections can be associated with unusual behaviors of the Titan airglow.