Date & Time: 2023/Oct./26  17:00-18:00, Venue: Zoom TV Conference System. This is an informal seminar on the formation of stars and planets. We welcome anyone interested in the subject.

Title:  Structure of Density-Bounded H II Regions

Speaker: Jeong-Gyu Kim (NAOJ)

Abstract: 

Both observations of massive star-forming regions and numerical simulations of GMCs with UV radiation feedback show that H II regions develop large holes through which UV radiation and ionized gas can escape. The presence of ionized gas outflows makes the photoevaporative mass loss efficient, while escaping ionizing photons are believed to be the primary source of the diffuse ionized gas and cosmic reionization. Despite their importance, however, theoretical models for "leaky" H II regions are still limited. We develop a model for the structure of ionized gas outflows in leaky HII regions that can be applied to a wide-range of star-forming environments. We quantify how the outflow rate and escape fraction of UV radiation vary with H II region's luminosity, size, dust optical depth, and gravity of neutral gas and stars. We find that the density profile is more centrally concentrated when there is relatively more supply of fresh ionized gas by photoevaporation in the inner region. Strong gravity can trap ionized gas and reduce the photoevaporation rate. Radiation pressure can enhance the outflow velocity and mass loss rate in compact and luminous H II regions. We also discuss implications of our results, including the dynamical ejection of neutral gas and faint ionized gas emission detected around H II regions.

他、会議報告、速報など、飛び入りも歓迎します。今回もしくは次回以降、話題提供できる方は世話人までメールしていただけましたら幸いです。 

Participants: 38,  Affiliations: 15

Participants list:

Tohoku: PD Ryunosuke MAEDA

Ibaraki U.: P. Munetake MOMOSE

UTokyo-Komaba: P Takeru Suzuki

UTokyo: P Yuri Aikawa, PD Anton Feeney-Johansson, PD Shota Notsu, D3 Yuki Yoshida, D2 Yoshihide Yamato, M2 Yuto Komichi, Intern Gabriel GUIMARÃES

JAMSTEC: PD Sota Arakawa

RIKEN: PD Ryosuke Tominaga

NAOJ: A Kazunari Iwasaki, PD Jeong-Gyu Kim, PD Yoshiaki Misugi

Nagoya U.: P Shu-ichiro Inutsuka, AP Hiroshi Kobayashi, A Valeska Valdivia, PD Daisei Abe, D2 Kanta Kitajima, D1 MiyayamaRyushi, D1 Tomotaka Nishikawa, M2 Kita Fumina, M2 Izumi SENO, M1 Wataru Takahashi, M1 Onogawa Kenshin

Kyoto: A Yuri Fujii 

Kindai: Retired/emeritus Kiguchi 

Shiga medical U.: AP Kazutaka Motoyama

Kobe: 特命A Kenji Kurosaki

Kyushu: D3 Asako Sato, D3 Naoto Harada, M2 Yuki Akaike, M1 Mitsuki Omura

Kagoshima: PD Sanemichi Takahashi, D1 Yudai Kobayashi

Cologne: PD Masato KOBAYASHI

次回：11/20-22, workshop @ Okinawa.  The next online seminar will be held on 2024 Jan.(TBD).

連絡世話人：冨永遼佑（理化学研究所） ryosuke.tominaga[at]riken.jp