Date & Time: 2024/April/11 (Thu.) 17:10-18:10, 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 first stars, the first generation of metal-free stars in the Universe, emerged around z~10-30. Recent hydrodynamics simulations have shown that circumstellar disks rapidly undergo gravitational instability, leading to disk fragmentation. Consequently, they tend to form as binaries or highly multiple systems containing both massive and low-mass stars. However, most simulations have not considered the influence of magnetic fields. In present-day star-forming clouds, coherent magnetic fields can remove angular momentum through magnetic torques (magnetic braking) or magnetohydrodynamic (MHD) outflows, resulting in reduced disk sizes and fragmentation. In the case of first star-forming clouds, turbulent dynamos can rapidly amplify weak fields to significant strengths with highly disturbed configuration. However the impact of such turbulent magnetic fields on first star formation remains unclear.
In this study, we perform 3D MHD simulations from the gravitational collapse of a turbulent cloud core to the accretion phase. Our results show that if magnetic fields are amplified to the equipartition level with turbulent energy during the collapse phase, turbulent magnetic fields can suppress disk fragmentation through the effects of magnetic torque and pressure. Although we also observe protostellar jets driven by magnetic pressure, their influence on star formation seems minimal. Our findings suggest that magnetic fields can suppress the formation of low-mass first stars, resulting in a top-heavy initial mass function.
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:34, Affiliations:13
Participants list:
Hosei: P Tomoaki Matsumoto
Ibaraki: P Munetake Momose, P Toru Turibe
JAMSTEC: PD Sota Arakawa
Kagoshima: PD Daisuke Takaishi, D2 Yudai Kobayashi
Konan U.: PD Kenji Eric Sadanari
Kyushu: D1 Ayumu Shoshi
Nagoya: P Shu-ichiro Inutsuka, AP Hiroshi Kobayashi, D3 Kanta Kitajima, D2 Ryushi Miyayama, D2 Tomotaka Nishikawa, D1 Izumi Seno, D1 Riona Yamada, M2 Kenshin Onogawa, M2 Wataru Takahashi, M1 Hayato Shimizu, M1 Kota Kobayashi, M1 Shusuke Utsumi, M1 Yuji Miko
NAOJ: PD Yuji Matsumoto
NIT: Fukushima A Yuki Tanaka
Osaka: A Shinsuke Takasao
Shiga medical: AP Motoyama
Tokyo Tech: PD Ryosuke Tominaga, D1 Ryota Yamamuro, D1 Taira Shintaro, M1 Issei Kojima
UTokyo: PD Naoto Harada, D3 Yoshihide Yamato, D2 Lily Ishizaki, D1 Yuto Komichi, M1 Kazuma Fukutomi
次回：2024/July/4 17:00-
連絡世話人：冨永遼佑（東工大） tominaga.r.aa[at]m.titech.ac.jp