Investigating the formation of very-low mass stars/brown dwarfs driven by turbulence with dense core observations

• Project/Area Number: 18K13582
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: Osaka Prefecture University
• Principal Investigator: Tokuda Kazuki 大阪府立大学, 理学(系)研究科(研究院), 客員研究員 (60802139)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2018: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
• Keywords: 電波望遠鏡 / 分子雲 / 分子雲コア / 小質量星形成 / 褐色矮星 / 褐色矮星形成 / ALMA / 星形成

Outline of Final Research Achievements

The formation mechanisms of very low-mass stars and brown dwarfs lag far behind those of stars with masses in the order of one solar mass. This is because we do not understand the formation mechanism of the very dense, low-mass gas clumps forming such tiny objects' seeds. In this study, we performed ALMA (Atacama Large Millimeter/submillimeter Array) observations of high-density cores in nearby star-forming regions. Our research demonstrated that the formation of very-low-mass stars and brown dwarfs might be caused by turbulence in high-density cores and/or the fragmentation from a cylindrical shape molecular cloud itself.

Academic Significance and Societal Importance of the Research Achievements

宇宙には様々な質量の恒星が存在する。しかしながら、どのようにして質量を獲得し、多様な質量の星が生まれるか、それがどのようなメカニズムで頻度分布が決定されるかは理解が進んでいない。特に太陽の8倍以上を持つ大質量星と太陽の0.1倍以下の質量の星の形成については理解されていない。本研究は質量の小さい側の星の形成機構について観測的に調べたものである。本研究では小さい質量の星に至る密度の高い塊(星の卵)が必ずしも一つの要因ではなく、太陽程度と同様なメカニズムで生まれることや複雑な超音速乱流の環境下で生まれるなど、多様であることを見出した。

Research Products

• [Int'l Joint Research] IRFU/Service dAstrophysique(フランス)
• [Int'l Joint Research] IRFU/Service dAstrophysique(フランス)
• [Int'l Joint Research] IRFU/Service dAstrophysique(フランス)
• [Journal Article] ALMA view of the Galactic super star cluster RCW?38 at 270?au resolution (2021)
  • Author(s): Torii Kazufumi、Tokuda Kazuki、Tachihara Kengo、Onishi Toshikazu、Fukui Yasuo
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 73 Issue: 1 Pages: 205-219
  • DOI: 10.1093/pasj/psaa115
  • Peer Reviewed
• [Journal Article] The formation of the young massive cluster B1 in the Antennae Galaxies (NGC?4038/NGC?4039) triggered by cloud?cloud collision (2021)
  • Author(s): Tsuge Kisetsu、Tachihara Kengo、Fukui Yasuo、Sano Hidetoshi、Tokuda Kazuki、Ueda Junko、Iono Daisuke
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 73 Issue: 2 Pages: 417-430
  • DOI: 10.1093/pasj/psab008
  • Peer Reviewed
• [Journal Article] FRagmentation and Evolution of Dense Cores Judged by ALMA (FREJA). I. Overview: Inner ?1000 au Structures of Prestellar/Protostellar Cores in Taurus (2020)
  • Author(s): Tokuda Kazuki、Fujishiro Kakeru、Tachihara Kengo、Takashima Tatsuyuki、Fukui Yasuo、Zahorecz Sarolta、Saigo Kazuya、Matsumoto Tomoaki、Tomida Kengo、Machida Masahiro N.、Inutsuka Shu-ichiro、Andr? Philippe、Kawamura Akiko、Onishi Toshikazu
  • Journal Title: The Astrophysical Journal Volume: 899 Issue: 1 Pages: 10-10
  • DOI: 10.3847/1538-4357/ab9ca7
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A Low-velocity Bipolar Outflow from a Deeply Embedded Object in Taurus Revealed by the Atacama Compact Array (2020)
  • Author(s): Fujishiro Kakeru、Tokuda Kazuki、Tachihara Kengo、Takashima Tatsuyuki、Fukui Yasuo、Zahorecz Sarolta、Saigo Kazuya、Matsumoto Tomoaki、Tomida Kengo、Machida Masahiro N.、Inutsuka Shu-ichiro、Andr? Philippe、Kawamura Akiko、Onishi Toshikazu
  • Journal Title: The Astrophysical Journal Volume: 899 Issue: 1 Pages: L10-L10
  • DOI: 10.3847/2041-8213/ab9ca8
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] ALMA Observations of Giant Molecular Clouds in M33. II. Triggered High-mass Star Formation by Multiple Gas Colliding Events at the NGC 604 Complex (2020)
  • Author(s): Muraoka Kazuyuki、Kondo Hiroshi、Tokuda Kazuki、Nishimura Atsushi、Miura Rie E.、Onodera Sachiko、Kuno Nario、Zahorecz Sarolta、Tsuge Kisetsu、Sano Hidetoshi、Fujita Shinji、Onishi Toshikazu、Saigo Kazuya、Tachihara Kengo、Fukui Yasuo、Kawamura Akiko
  • Journal Title: The Astrophysical Journal Volume: 903 Issue: 2 Pages: 94-94
  • DOI: 10.3847/1538-4357/abb822
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] The formation of young massive clusters triggered by cloud?cloud collisions in the Antennae galaxies NGC?4038/NGC?4039 (2020)
  • Author(s): Tsuge Kisetsu、Fukui Yasuo、Tachihara Kengo、Sano Hidetoshi、Tokuda Kazuki、Ueda Junko、Iono Daisuke、Finn Molly K
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 73 Issue: Supplement_1 Pages: S35-S61
  • DOI: 10.1093/pasj/psaa033
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] An ALMA View of Molecular Filaments in the Large Magellanic Cloud. I. The Formation of High-mass Stars and Pillars in the N159E-Papillon Nebula Triggered by a Cloud?Cloud Collision (2019)
  • Author(s): Fukui Yasuo、Tokuda Kazuki、Saigo Kazuya、Harada Ryohei、Tachihara Kengo、Tsuge Kisetsu、Inoue Tsuyoshi、Torii Kazufumi、Nishimura Atsushi、Zahorecz Sarolta、Nayak Omnarayani、Meixner Margaret、Minamidani Tetsuhiro、Kawamura Akiko、Mizuno Norikazu、Indebetouw Remy、Sewi?o Marta、Madden Suzanne、Galametz Maud、et al.
  • Journal Title: The Astrophysical Journal Volume: 886 Issue: 1 Pages: 14-14
  • DOI: 10.3847/1538-4357/ab4900
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] An ALMA View of Molecular Filaments in the Large Magellanic Cloud. II. An Early Stage of High-mass Star Formation Embedded at Colliding Clouds in N159W-South (2019)
  • Author(s): Tokuda Kazuki、Fukui Yasuo、Harada Ryohei、Saigo Kazuya、Tachihara Kengo、Tsuge Kisetsu、Inoue Tsuyoshi、Torii Kazufumi、Nishimura Atsushi、Zahorecz Sarolta、Nayak Omnarayani、Meixner Margaret、Minamidani Tetsuhiro、Kawamura Akiko、Mizuno Norikazu、Indebetouw Remy、Sewi?o Marta、Madden Suzanne、Galametz Maud、et al.
  • Journal Title: The Astrophysical Journal Volume: 886 Issue: 1 Pages: 15-15
  • DOI: 10.3847/1538-4357/ab48ff
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Nobeyama 45 m Cygnus-X CO Survey. II. Physical Properties of C18O Clumps (2019)
  • Author(s): Takekoshi Tatsuya、Fujita Shinji、Nishimura Atsushi、Taniguchi Kotomi、Yamagishi Mitsuyoshi、Matsuo Mitsuhiro、Ohashi Satoshi、Tokuda Kazuki、Minamidani Tetsuhiro
  • Journal Title: The Astrophysical Journal Volume: 883 Issue: 2 Pages: 156-156
  • DOI: 10.3847/1538-4357/ab3a55
  • Peer Reviewed / Open Access
• [Journal Article] A centrally concentrated sub-solar-mass starless core in the Taurus L1495 filamentary complex (2019)
  • Author(s): Tokuda Kazuki、Tachihara Kengo、Saigo Kazuya、Andre Phillipe、Miyamoto Yosuke、Zahorecz Sarolta、Inutsuka Shu-ichiro、Matsumoto Tomoaki、Takashima Tatsuyuki、Machida Masahiro N、Tomida Kengo、Taniguchi Kotomi、Fukui Yasuo、Kawamura Akiko、Tatematsu Ken’ichi、Kandori Ryo、Onishi Toshikazu
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 71 Issue: 4 Pages: 73-73
  • DOI: 10.1093/pasj/psz051
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Formation of high-mass stars in an isolated environment in the Large Magellanic Cloud (2019)
  • Author(s): Harada Ryohei、Onishi Toshikazu、Tokuda Kazuki、Zahorecz Sarolta、Hughes Annie、Meixner Margaret、Sewi?o Marta、Indebetouw Remy、Nayak Omnarayani、Fukui Yasuo、Tachihara Kengo、Tsuge Kisetstu、Kawamura Akiko、Saigo Kazuya、Wong Tony、Bernard Jean-Philippe、Stephens Ian W
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 71 Issue: 2 Pages: 44-44
  • DOI: 10.1093/pasj/psz011
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] FOREST Unbiased Galactic Plane Imaging Survey with the Nobeyama 45-m Telescope (FUGIN) V: Dense gas mass fraction of molecular gas in the Galactic plane (2019)
  • Author(s): Torii, Kazufumi; Fujita, Shinji; Nishimura, Atsushi; Tokuda, Kazuki; Kohno, Mikito; Tachihara, Kengo; Inutsuka, Shu-ichiro; Matsuo, Mitsuhiro; Kuriki, Mika; Tsuda, Yuya; Minamidani, Tetsuhiro; Umemoto, Tomofumi; Kuno, Nario; Miyamoto, Yusuke
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 印刷中
  • Peer Reviewed
• [Journal Article] Warm CO Gas Generated by Possible Turbulent Shocks in a Low-mass Star-forming Dense Core in Taurus (2018)
  • Author(s): Tokuda, Kazuki; Onishi, Toshikazu; Saigo, Kazuya; Matsumoto, Tomoaki; Inoue, Tsuyoshi; Inutsuka, Shu-ichiro; Fukui, Yasuo; Machida, Masahiro N.; Tomida, Kengo; Hosokawa, Takashi; Kawamura, Akiko; Tachihara, Kengo
  • Journal Title: The Astrophysical Journal Volume: 862 Issue: 1 Pages: 8-22
  • DOI: 10.3847/1538-4357/aac898
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] ALMA 高分解能データで探る星団形成領域 Corona Australis IRS7 における分子雲コアの分裂 (2022)
  • Author(s): 深谷直史, 立原研悟, 西岡丈翔, 徳田一起, 山崎康正, 原田直人, 山崎駿, 町田正博, 深川美里
  • Organizer: 日本天文学会2022年春季年会
• [Presentation] ALMA ACA サーベイで探る Corona Australis 領域の星形成 (4) (2022)
  • Author(s): 西岡丈翔, 立原研悟, 山崎康正, 徳田一起, 深谷直史, 大西利和, 金井昂大, 大朝由美子, 松下祐子, 西合一矢, 深川美里, 原田直人, 佐伯優, 柳玉華, 山崎駿, 町田正博, 深谷紗希
  • Organizer: 日本天文学会2022年春季年会
• [Presentation] ALMA ACA サーベイで探る Corona Australis 領域の星形成 (3) (2021)
  • Author(s): 西岡丈翔, 立原研悟, 山崎康正, 徳田一起, 大西利和, 金井昂大, 大朝由美子, 松下祐子, 西合一矢, 深川美里, 原田直人, 佐伯優, 柳玉華, 山崎駿, 町田正博, 深谷紗希子
  • Organizer: 日本天文学会2021年秋季年会
• [Presentation] ALMA ACA による小マゼラン雲超広域 CO 探査 (1): CO 分子雲の大局的分布 (2021)
  • Author(s): 徳田一起, Zahorecz Sarolta (大阪府大/国立天文台), 大野峻宏, 柘植紀節, 立原研悟, 福井康雄 (名古 屋大), 佐野栄俊, 河村晶子 (国立天文台), 近藤滉, 小西亜侑, 村岡和幸, 大西利和 (大阪府大), 福島肇 (筑波大), 竹腰達哉 (北見工業大)
  • Organizer: 日本天文学会2021年春季年会
• [Presentation] 小質量星形成極初期段階分子雲コアH3+重水素化合物の観測 (2021)
  • Author(s): 徳田一起
  • Organizer: ALMA高周波バンドを用いた星形成研究を考える
• [Presentation] 単一鏡と干渉計で明らかにする局所銀河群巨大分子雲の全貌 (2021)
  • Author(s): 徳田 一起
  • Organizer: (サブ)ミリ波単一鏡の革新で挑む, 天文学の未解決問題
• [Presentation] ALMA ACA サーベイで探る Taurus 領域分子雲コア進化の統計的研究 (4): N2D+ 輝線と1.3 mm連続波の比較から考察する分子雲コア進化段階 (2020)
  • Author(s): 徳田一起, Zahorecz Sarolta (大阪府大/国立天文台), 立原研悟, 福井康雄, 犬塚修一郎 (名古屋大), 松 下祐子, 西合一矢, 河村晶子 (国立天文台), 松本倫明 (法政大), 町田正博, 佐伯優, 原田直人, 柳玉華, 山崎駿 (九州大), 富田賢吾 (大阪大), 山崎康正, 大西利和 (大阪府大)
  • Organizer: 日本天文学会2020年秋季年会
• [Presentation] 最新電波望遠鏡で星の卵の進化を追う 星誕生の瞬間を求めて (2020)
  • Author(s): 徳田一起
  • Organizer: 2020年度 第50回 天文・天体物理若手夏の学校
  • Invited
• [Presentation] 局所銀河群の分子雲観測 (2020)
  • Author(s): 徳田一起
  • Organizer: 分子雲から原始星誕生までを追う ~新時代の星形成モデル構築に向けて~
• [Presentation] ALMAによるおうし座領域分子雲コアの統計的研究: 星なし分子雲コアからファーストコアまで (2020)
  • Author(s): 徳田一起
  • Organizer: 大研究会2020
• [Presentation] FRagmentation and Evolution of Dense Cores Judged by ALMA (FREJA): Inner ~1000 au Structures of Prestellar Cores in Taurus (2020)
  • Author(s): Kazuki Tokuda
  • Organizer: Cold Cores workshop in December 2020
  • Int'l Joint Research
• [Presentation] ALMA CO Observations toward Local Group of Galaxies (LMC/SMC/M33) (2020)
  • Author(s): Kazuki Tokuda
  • Organizer: ALMA Grant Fellow Symposium 2020
• [Presentation] ALMA ACA サーベイで探る Taurus 領域分子雲コア進化の統計的研究 (2): 1 mm 帯連続波で検出された分子雲コアの内部構造 (2020)
  • Author(s): 徳田一起, Zahorecz Sarolta (大阪府大/国立天文台), 藤城翔, 立原研悟, 福井康雄, 犬塚修一郎 (名古屋大), 西合一矢, 河村晶子 (国立天文台), 松本倫明 (法政大), 町田正博 (九州大), 富田賢吾 (大阪大), 高嶋辰幸, 大西利和 (大阪府大)
  • Organizer: 日本天文学会2029年春季年会
• [Presentation] ALMA による渦巻銀河 M33 の巨大分子雲の高分解能観測 (3): フィラメント状分子雲と原始星アウトフローの検出 (2019)
  • Author(s): 徳田一起 (大阪府大/国立天文台), 近藤滉, 村岡和幸, 西村淳, 大西利和 (大阪府立大学), 濤崎智佳 (上越教育大学), 三浦理絵, 西合一矢, 河村晶子, 鳥居和史 (国立天文台), 小野寺幸子 (明星大学), 久野成夫 (筑波大学), 藤田真司, 立原研悟, 福井康雄 (名古屋大)
  • Organizer: 日本天文学会2019年秋季年会
• [Presentation] Spatially resolved high-mass star-forming filamentary clouds in the Large Magellanic Cloud (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: ALMA/45m/ASTE Users Meeting 2019
• [Presentation] A detailed ALMA study of an early stage of protostar formation in a highly dynamical dense core (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: ALMA Workshop 2019: Early Planet Formation in Embedded Disks
  • Int'l Joint Research
• [Presentation] Spatially resolved filamentary clouds in the Large Magellanic Cloud (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: LINKING THE MILKY WAY AND NEARBY GALAXIES
  • Int'l Joint Research
• [Presentation] A detailed ALMA study of an early stage of protostar formation in a highly dynamical dense core (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: Zoom in on star formation
  • Int'l Joint Research
• [Presentation] ALMA studies of the substructure of protostellar/prestellar cores in Taurus (2019)
  • Author(s): Tokuda, Kazuki
  • Organizer: From Stars to Planets II - Connecting our understanding of star and planet formation
  • Int'l Joint Research
• [Presentation] Revealing the substructures of prestellar/protostellar cores with ALMA and the ngVLA (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: next generation VLA workshop
  • Int'l Joint Research
• [Presentation] Taurus dense core surveys with single-dishes and interferometers in the Heisei and Reiwa era (2019)
  • Author(s): 徳田一起
  • Organizer: Nobeyama Science Workshop -令和元年-
  • Invited
• [Presentation] L1495 領域のフィラメント雲に埋もれた褐色矮星前駆体候補の高密度コア (2019)
  • Author(s): 徳田一起, Zahorecz Sarolta, 立原研悟, 宮本洋輔, 福井康雄, 犬塚修一郎, Andre Phillipe, 西合一矢, 河村晶子, 立松健一, 松本倫明, 町田正博, 富田賢吾, 谷口琴美, 神鳥亮, 高嶋辰幸, 大西利和
  • Organizer: 日本天文学会2019年春季年会
• [Presentation] Revealing substructures of prestellar/protostellar cores in low-mass star-forming regions with ALMA (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: Star formation with ALMA: Evolution from molecular clouds to protostars
• [Presentation] Searching for starless cores as suitable targets for future polarization observations with ALMA Contribution (2019)
  • Author(s): Kazuki Tokuda
  • Organizer: Polarimetry in the ALMA era: a new crossroads of astrophysics
  • Int'l Joint Research
• [Presentation] 星形成初期段階分子雲コアの乱流ショックにより生じた暖かいCOガス (2018)
  • Author(s): 徳田一起 (大阪府大/国立天文台チリ観測所), 大西利和 (大阪府大), 西合一矢, 河村晶子 (国立天文台チリ観測所), 井上剛志, 犬塚修一郎, 福井康雄, 立原研悟 (名古屋大), 松本倫明 (法政大), 町田正博 (九州大), 細川隆史 (京都大), 富田賢吾 (大阪大)
  • Organizer: 日本天文学会2018年秋季年会
• [Presentation] 南極 30m 望遠鏡による近傍星形成領域の乱流起源高温ガス+マゼラン雲の観測 (2018)
  • Author(s): 徳田一起
  • Organizer: 南極 30m 級テラヘルツ望遠鏡によるサイエンス(星惑星系形成)
  • Invited
• [Presentation] Science cases of star formation with NOEMA/IRAM 30m (2018)
  • Author(s): Kazuki Tokuda
  • Organizer: NOEMA/30m Workshop
  • Invited
• [Presentation] Warm CO gas generated by possible turbulent shocks in a low-mass star-forming dense core in Taurus (2018)
  • Author(s): 徳田一起
  • Organizer: Workshop: Star Formation Triggered by Cloud-Cloud Collision
• [Presentation] Warm CO filamentary/clumpy gas generated by possible turbulent shocks in a highly dynamical dense core in Taurus resolved by ALMA (2018)
  • Author(s): Kazuki Tokuda
  • Organizer: East Asian ALMA Development Workshop 2018
  • Int'l Joint Research
• [Presentation] Warm CO filamentary/clumpy gas generated by possible turbulent shocks in a highly dynamical dense core in Taurus resolved by ALMA (2018)
  • Author(s): Kazuki Tokuda
  • Organizer: East Asian ALMA Science Workshop 2018
  • Int'l Joint Research
• [Presentation] Warm CO filamentary/clumpy gas generated by possible turbulent shocks in a highly dynamical dense core in Taurus resolved by ALMA (2018)
  • Author(s): Kazuki Tokuda; Toshikazu Onishi; Kazuya Saigo; Tomoaki Matsumoto; Tsuyoshi Inoue; Shu-ichiro Inutsuka; Yasuo Fukui; Masahiro N. Machida; Kengo Tomida; Takashi Hosokawa; Akiko Kawamura; Kengo Tachihara
  • Organizer: Interstellar filament paradigm: On their formation, evolution, and role in star formation
  • Int'l Joint Research
• [Presentation] A detailed ALMA study of an early stage protostar formation in a highly dense core (2018)
  • Author(s): Kazuki Tokuda
  • Organizer: The Wonders of Star Formation
  • Int'l Joint Research
• [Presentation] 分子雲コア中心部に埋もれた~0.2Mo原始星に付随する~10AU円盤のALMA長基線観測 (2018)
  • Author(s): 徳田一起
  • Organizer: ALMAワークショップ：円盤から太陽系へ
• [Remarks] アルマ望遠鏡が追う星のヒナ誕生までの10万年―星の卵の「国勢調査」―
  • URL: https://www.osakafu-u.ac.jp/press-release/pr20200807/