PPARCセミナー (2025/07/28)
PPARCセミナー (2025/07/28)
(1)
[Name]
Shinnosuke Satoh
[Title]
A report on the research stay in Marseille, France
[Abstract]
I’ll briefly talk about the research experiences at Laboratoire d’Astrophysique de Marseille, including two missions to Toulouse and Liége to discuss science with some colleagues. This three-and-half-month research stay in France has been quite an experience, definitely broadening my perspective and knowledge. Hopefully this talk will encourage some of you to reach out a lot of international colleagues and do a research visit/stay overseas.
(2)
[Name]
Leah Clare
[Title]
The Temporal Variability of Saturn’s UV Dayside Disk Emission: A Comparative Study Using Hisaki & Cassini
[Abstract]
The atmosphere of Saturn is primarily composed of molecular hydrogen (H2), which emits ultraviolet (UV) light when excited by various mechanisms. Understanding the variability and drivers of these emissions is key to probing the dynamics and energy input into Saturn’s upper atmosphere. H2 UV emissions have been observed since the Voyager 1 and 2 missions, with the brightest originating from auroral regions, produced by electron impact excitation of atmospheric constituents (Lamy et al., 2013). In addition to auroral emissions, Saturn’s atmosphere exhibits airglow, with stronger intensities observed on the dayside (dayglow) compared to the nightside (Broadfoot et al., 1981). Studying these dayside disk emissions provides valuable insight into the interaction between the solar flux and Saturn’s atmosphere, as solar activity has been previously shown to correlate with UV emission variability (Clarke et al., 1987; McGrath & Clarke, 1992). H2 dayglow is thought to be primarily driven by electron impact excitation and solar fluorescence, with models and Cassini UVIS limb-scan data estimating an average contribution of 68% from electron impact excitation (Gustin et al., 2010). This study uses Hisaki observations of Saturn over a ~3-week period in May–June 2014 to investigate the temporal variability of H2 dayside disk emissions. These data are compared with simultaneous Cassini UVIS measurements to further assess the reliability of Hisaki for outer planet UV observations. We find that H2 disk brightnesses vary by up to a factor of 2.7 over the observing period. A Pearson correlation coefficient of 0.7 – 0.72 is observed between Hisaki emission power variability and solar activity proxies, supportive of a significant solar control on the dayside disk emission.
