Home > ALMA Jセミナー | 太陽系小天体セミナー > 2021.4.5-2021.4.11

2021.4.5-2021.4.11

4月6日(火)10:00~11:30   太陽系小天体セミナー               zoom
Apr 6 Tue           Solar System Minor Body Seminar 

4月7日(水)15:00~16:00   ALMA-J Seminar                zoom
Apr 7 Wed             

詳細は以下をご覧下さい。

4月6日(火)

キャンパス
三鷹
セミナー名
太陽系小天体セミナー
定例・臨時の別
定例
日時
4月6日(火曜日)10時00分~11時30分
場所
zoom

連絡先
 名前:渡部潤一
備考
テレビ会議またはスカイプによる参加も可

4月7日(水)

Campus
Mitaka
Seminar
ALMA-J seminar
Regularly Scheduled/Sporadic
Every Wednesday
Date and time
2021 Apr. 7 15:00-16:00
Place
Zoom
Speaker
Takahiro Iino (University of Tokyo)
Title
A Belt-like Distribution of Gaseous Hydrogen Cyanide on Neptune’s Equatorial Stratosphere Detected by ALMA
Abstract
We present a spatially resolved map of integrated-intensity and abundance of Neptune’s stratospheric hydrogen cyanide (HCN). The analyzed data were obtained from the archived 2016 observation of the Atacama Large Millimeter/submillimeter Array. A 0″42 × 0″39 synthesized beam, which is equivalent to a latitudinal resolution of ˜20° at the disk center, was fine enough to resolve Neptune’s 2″24 diameter disk. After correcting the effect of different optical path lengths, a spatial distribution of HCN emissions is derived over Neptune’s disk, and it clearly shows a band-like HCN enhancement at the equator. Radiative transfer analysis indicates that the HCN volume mixing ratio measured at the equator was 1.92 ppb above the 10-3 bar pressure level, which is 40% higher than that measured at the southern middle and high latitudes. The spatial distribution of HCN can be interpreted as either the effect of the transportation of N2 from the troposphere by meridional atmospheric circulation, or an external supply such as cometary collisions (or both of these reasons). From the meridional circulation point of view, the observed HCN enhancement on both the equator and the pole can be explained by the production and accumulation of HCN at the downward branches of the previously suggested two-cell meridional circulation models. However, the HCN-depleted latitude of 60° S does not match with the location of the upward branch of the two-cell circulation models. Adding to a result of Neptune above, we will introduce our recent achievements of planetary atmospheric chemistry on Titan.
Facilitator
Hiroshi NAGAI

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