Date & Time: 2024/October/10 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.
Abstract:
The dissipation of protoplanetary disks is a crucial physical process in the evolution of the disks and planetary formation within them. Photoevaporation caused by X-rays and ultraviolet radiation from the central star has attracted attention as a key process driving gas dissipation. While several models of disk dissipation based on photoevaporation have been proposed, their outcomes differ significantly, preventing a definitive conclusion. One factor is the artificial assumptions on the stellar radiation spectrum, particularly the unobservable extreme ultraviolet radiation, used as input parameters in the photoevaporation models. In classical T Tauri stars with circumstellar disks, radiation from the magnetically heated atmosphere (corona) and from accretion shocks are both considered important, and this diversity in radiation origins complicates reliable spectrum estimation. To address this issue, it is necessary to separately understand the radiation properties of accretion shocks and the corona.
In this study, we focus on TW Hya, a classical T Tauri star, to model its XUV (X-ray, extreme ultraviolet) radiation from the corona. To achieve this, we applied a numerical model capable of reproducing the XUV radiation of solar-type stars (Shoda & Takasao 2021, Shoda, Namekata & Takasao 2024) to TW Hya and conducted simulations using the observed magnetic flux and chemical composition as input. The results show that the intensity of X-ray emission lines formed at relatively high temperatures was reproduced within a factor of about 3. On the other hand, the intensity of X-ray emission lines formed at relatively low temperatures is systematically underestimated. This is consistent with observational findings that X-rays formed at lower temperatures originate from accretion shocks. These results suggest the potential for reconstructing the radiation spectrum of classical T Tauri stars using numerical models.
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Participants:38, Affiliations:14
Participants list:
Ibaraki: P Munetake Momose, D3 Ryuta Orihara
JAXA/ISAS: PD Mai Yamashita
Kagoshima: D2 Miyu Kido
Kindai: Masayoshi Kiguchi
Kobe: DA Kenji Kurosaki
Kurume: L Masanobu Kunitomo
Kyoto: A Yuri Fujii
Kyushu: D1 Ayumu Shoshi
Nagoya: P Shu-ichiro Inutsuka, AP Hiroshi Kobayashi, D3 Kanta Kitajima, D2 Tomotaka Nishikawa, D1 Riona Yamada, D1 Izumi Seno, M2 Kenshin Onogawa, M2 Wataru Takahashi, M1 Hayato Shimizu, M1 Kota Kobayashi, M1 Shusuke Utsumi, M1 Yuji Miko, B4 Yuki Tamaki
NAOJ: PD Yuji Matsumoto, PD Yoshiaki Misugi
Osaka: A Shinsuke Takasao
Science Tokyo: PD Ryosuke Tominaga, D3 Yuya Fukuhara, D1 Shintaro Taira, Yuto Kajikiya
Tohoku: PD Daisei Abe, M1 Haruki Nabeta
UTokyo: P Yuri Aikawa, A Munehito Shoda, A Shota Notsu, PD Naoto Harada, D3 Kaho Morii, D3 Yoshihide Yamato, D1 Yuto Komichi
次回：2024/Nov./15 17:00-
連絡世話人：冨永遼佑（東京科学大学） tominaga.r.aa[at]m.titech.ac.jp