PPARC セミナー (2024/12/11)
PPARC セミナー (2024/12/11)
(1) Masamichi Waga
[Title]
GMRT解析パイプラインspamを用いた木星放射線帯の空間構
[Abstract]
木星シンクロトロン放射(JSR)は、
(2) Masato Kagitani
[Title]
Daytime monitoring of Mercury’s sodium exosphere with Haleakala T60 adaptive optics
[Abstract]
Mercury has tenuous surface-bounded exosphere containing H, He, O, Na, Ca, and K. The resonant scattering emission of the Na D-lines (589.0 nm and 589.6 nm) is bright enough to be observable from Earth. The typical time scales for variability expected from the interaction with the solar wind are on the order of a few minutes.Previous ground-based observations have shown that the north-south ratio of brightness in the Na exosphere changes on a time scale of several tens of minutes, which is consistent with the brightness response due to magnetospheric particle sputtering. There are also some global brightness patterns in Na exosphere. However, previous observations using the slit scanning technique took about an hour to get Mercury’s global Na brightness distribution. Using a high-resolution spectrograph (R=50,000) equipped with an integral field unit (IFU) installed on the T60, our objective is to obtain 2-dimensional spectroscopic observation with a cadence of 5 minutes. Mercury’s maximum elongation from the Sun is only about 24+/-4 degrees. Pointing a telescope close to the Sun is usually hazardous except for solar telescope. Therefore, with normal telescopes, observations are limited to about an hour after sunset or before sunrise. To monitor the Mercury’s exospheric Na brightness through the coordinated observation with the BepiColombo mission, it is necessary to carry out continuous observations not only during short periods after sunset or before sunrise, but also during the daytime when the atmospheric seeing condition is poor (2 to 5” typically). Our visible AO system installed on T60 (T60-AO) aims to stably observe Mercury with a spatial resolution of 1.5 arc-seconds, or bettern than one fifth of disk diameter even during daytime with poor seeing conditions. I will present the latest results of Mercury observations using T60 and introduce the upgrade plans scheduled for late December.
