Date & Time: 2024/Apr./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.

Title:  Effects of turbulent magnetic fields on disk fragmentation in first star

Speaker:  定成 健児エリック (甲南大学)

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/May/16 

連絡世話人：冨永遼佑（東工大） tominaga.r.aa[at]m.titech.ac.jp