Riouhei Nakatani (Ryohei Nakatani)

Ph.D. student at Department of Physics, School of Science, The University of Tokyo
Research interest: Star-planet system formation, Hydrodynamics simulation

email: r.nakatani_at_utap.phys.s.u-tokyo.ac.jp
office: Room 923, Faculty of Science Bldg.1, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo




I'm a Ph.D. student at the University of Tokyo, studying Astrophysics. I'm especially interested in star-planet system formation. It's fascinating that understanding the formation processes could provide information on the origins of our Solar system, which has interested me since I was a child, and even ourselves.


I'm currently working on a study about the dispersal process of protoplanetary disks, performing radiation hydrodynamics simulations of photoevaporation. Specifically, I'm investigating how disk metallicity affects mass loss due to photoevaporation and change the disk lifetime. Since the lifetime sets a time limit for planet formation, to understand lifetimes of protoplanetary disks with various metallicities is necessary to understand planet formation in not only our Solar system but also other different metallicity environments such as inner/outer Galaxy, early universe, etc.



Under construction... (April 2018)


Last Update: September 10, 2018



  • Apr. 2016 - : Ph.D. course at Department of Physics, School of Science, The University of Tokyo
  • Apr. 2014 - Mar. 2016: Master at Department of Physics, School of Science, The University of Tokyo; Thesis Subject: 'Photo-evaporation of a protoplanetary disk'
  • Apr. 2010 - Mar. 2014: Bachelor at Department of Physics, Faculty of Science, Osaka University; Thesis Subject: 'Evaporation Times of High-Dimensional Blackholes'
  • Apr. 2007 - Mar. 2010: Tochiku High School (福岡県立東筑高等学校)


  • Apr. 2016 - Mar. 2019: Research Fellow (DC1) of Japan Society for Promotion of Science (JSPS)
  • Oct. 2017 - Dec. 2017: Program student of JVSRP at NASA Jet Propulsion Laboratory (JPL)
  • Oct. 2014 - Mar. 2019: Program student of Advanced Leading Graduate Course for Photon Science (ALPS)


4) Photoevaporation of Molecular Gas Clumps Illuminated by External Massive Stars: Clump Lifetimes and Metallicity Dependence
Riouhei Nakatani & Naoki Yoshida
arXiv:1811.00297 (Submitted to ApJ)
3) Super-Eddington accretion of dusty gas onto seed black holes: metallicity-dependent efficiency of mass growth
Daisuke Toyouchi, Takashi Hosokawa, Kazuyuki Sugimura, Riouhei Nakatani, & Rolf Kuiper
arXiv:1811.01368 (Accepted for publication in MNRAS)
2)Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks II: Metallicity Dependence of UV and X-Ray Photoevaporation
Riouhei Nakatani, Takashi Hosokawa, Naoki Yoshida, Hideko Nomura, & Rolf Kuiper
The Astrophysical Journal, 865, 75 (2018)
1)Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks by Ultraviolet Radiation: Metalliciity Dependence
Riouhei Nakatani, Takashi Hosokawa, Naoki Yoshida, Hideko Nomura, & Rolf Kuiper
The Astrophysical Journal, 857, 57 (2018)


----- International Conferences -----
5) "Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks: Metallicity Dependence of UV and X-ray Photoevaporation"
Riouhei Nakatani, Takashi Hosokawa, Naoki, Yoshida, Hideko Nomura, & Rolf Kuiper
RESCEU Summer School (@ Yunokawa Kahantei, Hakodate, Hokkaido, Japan; Jul. 27-30, 2018)
4) "Radiation-Hydrodynamical Simulations of Photoevaporating Protoplanetary Disks with Various Metallicities"
Riouhei Nakatani, Takashi Hosokawa, Naoki, Yoshida, Hideko Nomura, & Rolf Kuiper
SFDE17: from Local Clouds to Distant Galaxies (@ ICISE, Quy Nhon, Vietnam; Aug. 7-11, 2017)
3) "Radiation-hydrodynamical simulations of photoevaporating protoplanetary disks with various metallicities"
Riouhei Nakatani, Takashi Hosokawa, Naoki, Yoshida, Hideko Nomura, & Rolf Kuiper
Francessco’s Legacy - Star Formation in Space and Time (@ Istituto degli Innocenti, Firenze, Italy; Jun. 5-9, 2017)
2) "METALLICITY DEPENDENCE OF PHOTOEVAPORATION RATE IN PROTOPLANETARY DISKS"
Ryohei Nakatani, Takashi Hosokawa, & Naoki Yoshida
APCosPA-Planet RESCEU Summer School (@ Hida-Takayama Garyu-no-Sato, Gifu, Japan; Aug. 24-26, 2016)
1) "Metallicity Dependence of Protoplanetary Disk’s Lifetime"
Ryohei Nakatani
Star/Planet Formation Meeting (@ The University of Tokyo, Tokyo, Japan; Apr. 9, 2015)

----- Domestic Conferences -----
13) "原始惑星系円盤の光蒸発"
仲谷崚平
ALMAワークショップ:円盤から太陽系へ (@ WTC Conference Center Tokyo; 2018年11月21-22日; Invited)
12) "原始惑星系円盤光蒸発の輻射流体シミュレーション:紫外・X線光蒸発の金属量依存性"
仲谷崚平
新学術「星惑星形成」第一回研究会 (@ 名古屋大学; 2018年9月13-14日)
11) "原始惑星系円盤における紫外線/X線光蒸発の金属量依存性"
仲谷崚平, 細川隆史, 吉田直紀, 野村英子, Rolf Kuiper
日本天文学会2018年春季年会 (@ 千葉大学; 2018年3月14-17日)
10) "原始惑星系円盤における紫外線/X 線光蒸発の輻射流体シミュレーション:金属量依存性"
仲谷崚平, 細川隆史, 吉田直紀, 野村英子, Rolf Kuiper
理論懇シンポジウム「星の物理の新地平」 (@ 東京大学; 2017年12月25-27日)
9) "原始惑星系円盤における光蒸発の金属量依存性"
仲谷崚平, 細川隆史, 吉田直紀, 野村英子, Rolf Kuiper
「天体形成論〜過去・現在・未来〜」 (@ 筑波大学; 2017年9月19-21日)
8) "円盤光蒸発の再考・議論"
仲谷崚平
原始星と原始惑星系円盤の形成進化過程についてのワークショップ (@ 九州大学; 2017年8月17-18日)
7) "原始惑星系円盤における光蒸発の金属量依存性"
仲谷崚平, 細川隆史, 吉田直紀, 野村英子, Rolf Kuiper
基研研究会「原始惑星系円盤」 (@ 京都大学; 2017年7月10-12日)
6) "原始惑星系円盤光蒸発の金属量 依存性"
仲谷崚平, 細川隆史、吉田直紀、野村英子、Rolf Kuiper
日本天文学会 2017 年春季年会 (@ 九州大学; 2017年3月15-18日)
5) "原始惑星系円盤における光蒸発の金属量依存性"
仲谷崚平, 細川隆史、吉田直紀、野村英子、Rolf Kuiper
原始星と原始惑星系円盤の形成進化過程についてのワークショップ (@ JR 博多シティアミュプラザ; 2016年12月27-28日)
4) "原始惑星系円盤の光蒸発"
仲谷崚平, 細川隆史, 吉田直紀
日本天文学会 2016 年秋季年会 (@ 愛媛大学; 2016年9月13-16日)
3) "原始惑星系円盤の光蒸発 I: 輻射流体コードの開発"
仲谷崚平
日本天文学会 2015 年秋季年会 (@ 甲南大学; 2015年9月9-11日)
2) "原始惑星系円盤寿命の金属量依存性"
仲谷崚平
星形成議論発表会 (@ 名古屋大学; 2015年3月17日)
1) "ケプラー宇宙望遠鏡を用いたトランジット惑星の質量推定"
仲谷崚平
天文若手夏の学校 (@ 長野; 2014年7月28-31日)

----- Seminars -----
8) "Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks: Metallicity Dependence of UV and X-Ray Photoevaporation"
R. Nakatani
DTA Colloquium (@ NAOJ, Tokyo, Japan; Jul. 10, 2018; Invited)
7) "Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks: Metallicity Dependence"
R. Nakatani, T. Hosokawa, N. Yoshida, H. Nomura, R. Kuiper
Astrophyics Seminar (@ The University of Tokyo, Tokyo, Japan; Jun. 7, 2018; Invited)
6) "Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks: Metallicity Dependence"
R. Nakatani, T. Hosokawa, N. Yoshida, H. Nomura, R. Kuiper
OUTAP Colloquium (@ Osaka University, Osaka, Japan; Jan. 24, 2018; Invited)
5) "Radiation Hydrodynamics Simulations of Photoevaporation of Protoplanetary Disks by Ultraviolet Radiation: Metallicity Dependence"
R. Nakatani, T. Hosokawa, N. Yoshida, H. Nomura, R. Kuiper
Astrophysical Journal Seminar (@ Jet Propulsion Laboratory, CA, USA; Dec. 11, 2017)
4) "The metallicity dependence of photoevaporation out of a protoplanetary disk"
R. Nakatani, T. Hosokawa, N. Yoshida, H. Nomura, R. Kuiper
Kolloquium SS17 (@ Universität Tübingen, Tübingen, Germany; Jun. 12, 2017; Invited)
3) "Radiation-Hydrodynamical Simulations of Photoevaporating Protoplanetary Disks with Various Metallicities"
R. Nakatani, T. Hosokawa, N. Yoshida, H. Nomura, R. Kuiper
Ta-Lab Colloquium (@ Nagoya University, Nagoya, Japan; May 16, 2017)
2) "Metallicity Dependence of Photoevaporation Out of a Protoplanetary Disk"
R. Nakatani
Astrophysics Colloquium (@ Konan University, Hyogo, Japan; Nov. 29, 2016)
1) "Photo-Evaporation of a Protoplanetary Disk"
R. Nakatani
Astrophysical Journal Seminar (@ Jet Propulsion Laboratory, CA, USA; Apr. 14, 2016)