Yuta Notsu (野津 湧太)
Research Scientist II
Laboratory for Atmospheric and Space Physics (LASP) , University of Colorado Boulder (CU Boulder)
Affiliated with National Solar Observatory (NSO)
[Full CV] | [Google Scholar] [NASA/ADS] [ORCID: 0000-0002-0412-0849] [Web of Science: ITV-3585-2023] [Researchmap 🇯🇵: R000039031 ]
Email: Yuta.Notsu_at_colorado.edu (Please replace "_at_" with "@".)
Research overview
I am an observational astrophysicist studying magnetic activity on the Sun and stars, with a particular focus on flares and coronal mass ejections (CMEs) on Sun-like stars and cool K- and M-dwarf stars. Using multi-wavelength observations from space- and ground-based telescopes—including HST, TESS, XMM-Newton, Swift, NICER, the Apache Point Observatory 3.5m telescope, SMARTS 1.5m, and the Seimei 3.8m telescope—I investigate how stellar flares and CMEs are generated, how their emission evolves across the photosphere, chromosphere, and corona, and how these energetic events affect planetary atmospheres and habitability. A major goal of my research is to connect solar, stellar, and planetary observations to build a broader understanding of magnetic activity and space weather across different stars and planetary systems.
Keywords:
Solar and stellar flares and superflares
Stellar coronal mass ejections
Multi-wavelength flare physics from the optical/UV to X-rays
Stellar high-energy emissions and energetic particles, and their effects on (exo)planetary atmospheres and habitability
Solar–stellar-planetary connections across heliophysics/astrophysics/planetary science fields
Current Major Research Projects
Multi-Wavelength Stellar Flare/CME Observations
I lead and contribute to coordinated observing programs combining space- and ground-based facilities to characterize the temporal evolution and atmospheric structure of stellar flares.
Current and recent PI programs include observations with HST, XMM-Newton, TESS, Swift, NICER, APO 3.5m, Las Cumbres Observatory, and other facilities.
Stellar Activity and Planetary Atmospheric Escape
NASA Heliophysics Living With a Star (H-LWS) Focused Science Team
Principal Investigator (PI) & Focused Science Team Lead | 2025–present
Comparison of stellar steady-state and transient phenomena affecting planetary atmospheric escape and habitability
This project brings together solar, stellar, and planetary perspectives to understand how both steady-state and transient stellar activity influence atmospheric escape and planetary habitability.
High-Energy Particle Environments of Stellar Flares
NASA Exoplanets Research Program (XRP)
Principal Investigator (PI) | 2026–present
Constraining high-energy particle environments in M-dwarf flares to understand their impacts on planets
The project aims to constrain the energetic-particle environments associated with M-dwarf flares and evaluate their effects on surrounding planetary atmospheres.
Funded Research Programs
2026 - Current : NASA ROSES 2025, Exoplanets Research Program (XRP), NNH25ZDA001N-XRP (PI, $588.9K, ID: 25-XRP25_2-0146)
"Constraining high-energy particle environments in M-dwarf flares to understand their impacts on planets"
2026 - Current : TESS Cycle 8 Guest Investigator Program (PI, $90K, ID: 8026)
“Solar-Like Periodic Modulations And Flare Emissions From The Nearest Neighbour Proxima Centauri”
2025 - Current: NASA ROSES 2024, Heliophysics Living With a Star Science (H-LWS) Science Program
NNH24ZDA001N-LWS (PI, $986.1K, ID: 24-LWS24_2-0044)
Also selected to be the Focused Science Team Lead (FST Team webpage)
“Comparison of stellar steady state and transient phenomena affecting planetary atmospheric escape and habitability”
2025 - Current: TESS Cycle 7 Guest Investigator Program (PI, $70K, ID:7095)
“High-Time Resolution Multi-Color Properties of Stellar Flares on G-M Dwarfs”
2024 - Current: Swift Cycle 20 Guest Investigator Program (PI, $40K, ID:2023095)
“Simultaneous SWIFT/UVOT NUV Photometry with the HST Treasury Program NUV Spectroscopy and TESS Photometry”
2024 - 2026: NICER Cycle 6 Guest Observer Program (PI, $38.5K, ID:7055)
“Simultaneous X-ray Monitoring of M Dwarf Flares with the HST Treasury Program NUV Spectroscopy and TESS Photometry”
2024 - 2026: TESS Cycle 6 Guest Investigator Program (PI, $70K, G06171)
“High-Time Resolution Multi-Color Properties of Stellar Flares”
[Earlier support]
Selected in 2023 : JSPS (Japan Society for the Promotion of Science; 日本学術振興会) Grant for Young researchers "Stellar superflares invesitigated with collaborative spectroscopic and photometric observations " Program Number 23K13143 (Grant suspended after my transition to a U.S.-based position)
2021.04 - 2023. 03: JSPS (Japan Society for the Promotion of Science) Research Fellow PD (Fellowship + Grant) : "Stellar superflares investigated with spectroscopic observations and their effects on planets" Project/Area Number: 21J00106 (Fellowship ended early in March 2023 following my transition to a U.S.-based position.)
2019.04 – 2021.03 : Overseas Research Fellowship of Japan Society for the Promotion of Science “Spectroscopic studies of solar-type superflare stars and their large starspots”
April 2016 - March 2019 : Research Fellow of Japan Society for the Promotion of Science (DC1) (Fellowship + Grant) : "Magnetic Activity of solar-type stars and dynamo theory investigated through the observations of superflare stars" Project/Area Number: 16J00320
July 2017 : Finantial support for attending 2nd LAMOST-Kepler Workshop from the 98th Hayakawa Satio Fund awarded by the Astronomical Society of Japan
November 2015 : Finantial support for attending K2 Science Conference from the 91th Hayakawa Satio Fund awarded by the Astronomical Society of Japan
August 2015 : Finantial support for attending IAU Symposium 320 by the educational program for graduate students organized by Unit of Synergetic Studies for Space, Kyoto University.
Selected Telescope Observations
- Space-Based Telescope Proposal Experience
Hubble Cycle 34 Guest Observer Program (ID: 18382, as PI, 18 HST orbits + 80-ks XMM-Newton joint time)
"All together Now: Improving Constraints of Stellar Flare Impact on Planetary Atmosphere"
TESS Cycle 9 Guest Investigator Progam (ID: G09084, as Co-I, PI: Isaiah Tristan, Link to the selected program list)
"Coordinated TESS And Radio Monitoring Of Flares On UV Ceti And Surrounding Stars"
TESS Cycle 8 Guest Investigator Program (ID: G08026, as PI, Link to the selected program list, with 100-ks Swift observations)
“Solar-Like Periodic Modulations And Flare Emissions From The Nearest Neighbour Proxima Centauri”
VLA - HST - XMM-Newton joint program observations through 2025B NRAO/VLA program
ID: VLA/25B-101, as Co-I, PI: I. Tristan, Listed of the approved programs , 20 hours VLA + 12 HST orbits + 72-ksec XMM-Newton
“Accelerating Our Models of Stellar Flare Particles”
XMM AO24 (as Co-I, PI: Adina Feinstein, ID:096244)
"A Multi-Wavelength Flare Campaign for AU Mic from the X-ray to the Infrared"
TESS Cycle 7 Guest Investigator Program (ID: G07095, as PI, Link to the selected program list)
“High-Time Resolution Multi-Color Properties Of Stellar Flares On G - M DWARFS”
Swift Cycle 20 Guest Investigator Program (ID: 2023095, as PI, List of the approved programs )
“Simultaneous SWIFT/UVOT NUV Photometry with the HST Treasury Program NUV Spectroscopy and TESS Photometry”
NICER Cycle 6 Guest Observer Program (ID: 7055, as PI, List of the approved programs )
“Simultaneous X-ray monitoring of M dwarf flares with the HST Treasury Program NUV spectroscopy and TESS photometry”
Hubble Cycle 31 Guest Observer Program (ID: 17464, as Co-I, PI: A. Kowalski, 88 HST orbits)
“From High-Energy Particle Beam Heating in Stars to Ozone Destruction in Planets: NUV Spectra as the Fulcrum for a Comprehensive Understanding of Flaring M Dwarf Systems”
TESS Cycle 6 Guest Investigator Program (ID: G06171, as PI, Link to the selected program list)
High-Time Resolution Multi-Color Properties of Stellar Flares”
- Ground-Based Telescope Observation/Proposal experiences
ARC 3.5m telescope at Apache Point Observatory, New Mexico (Instrument: ARCES&ARCTIC): > 100 half nights (as PI)
ARCSAT0.5m telescope at Apache Point Observatory, New Mexico (Instrument: flarecam) : > 50 nights (as PI)
Las Cumbres Observatory (1m + 0.4m photometry): >100 hours (as PI)
Subaru 8.2m telescope at Maunakea, Hawaii (Instrument: HDS): 7 nights (as PI)
3.8m Seimei Telescope at Okayama Observatory, Kyoto University, Japan: 2 ToO proposals (as PI) and many Co-I programs
1.88m telescope at Okayama Astrophysical Observatory, Japan (Instrument: HIDES): >40 nights (as PI and Co-I)
Several VLA (radio) programs as Co-I
Academic positions
2023.12 - Current : Research Scientist II (Research Associate)
Laboratory for Atmospheric and Space Physics (LASP) , University of Colorado Boulder (CU Boulder)
Also affiliated with National Solar Observatory (NSO, located in LASP)
2023.04 - 2023.11 : Research Scientist I (Research Associate)
Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder (CU Boulder)
Also affiliated with National Solar Observatory (NSO, located in LASP)
2021.04 - 2023.03 : Research Scientist I (Research Associate) at [1]
& JSPS Research Fellow PD (日本学術振興会特別研究員PD) at [2]
[1] Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder (CU Boulder)
Also affiliated with National Solar Observatory (NSO, located in LASP)
[2] Department of Earth and Planetary Sciences, School of Science, Tokyo Institute of Technology (Tokyo Tech)
(Long-term staying at LASP/CU, Early termination on 2023.03 because I moved completely to the US institution)
2019.04 - 2021.03 : JSPS Overseas Research Fellow (日本学術振興会海外特別研究員)
Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder (CU Boulder)
Also affiliated with National Solar Observatory (NSO, located in LASP)
2016.04 - 2019.03 : JSPS Research Fellow DC1 (日本学術振興会特別研究員DC1)
Department of Astronomy, Graduate School of Science, Kyoto University
2014.04 - 2016.03 : Teaching Assistant, Kyoto University
Education
2016.04 - 2019.03 : Ph.D. (astronomy)
Department of Astronomy, Graduate School of Science, Kyoto University
Ph. D. thesis "Observational studies on solar-type superflare stars" doi:10.14989/doctor.k21575)
2014.04 - 2016.03 : Master Degree of Science
Department of Astronomy, Graduate School of Science, Kyoto University
Master Thesis: "High dispersion spectroscopy of solar-type superflare stars"
2010.04 - 2014.03 : Bachelor of Science
Department of Astronomy, Faculty of Science, Kyoto University
2007.04 - 2010.03 : Graduated from Kyoto Prefectural Rakuhoku High School (Kyoto, Japan)
Honors & Awards
2024, Jan : PASJ excellent paper award (FY2023) on the co-author paper (Namekata et al. 2020, PASJ, 72, 68)
2016, May : Repayment Exemption for Students with Excellent Grades in FY2015, Japan Student Services Organization (JASSO) Type I (interest-free) scholarship
2014, July : Oral Award in Young Japanese Astronomers' Meeting 2014 link
Professional Service & Collaborations
Professional Service
Organizing Monthly Atmospherice Escape Seminar (Recording available)
Referee for articles in ApJ, ApJS, ApJL, A&A, MNRAS, Nature, Nature Astronomy, Nature Communications
Reviewer for some observatory & funding proposals
Served/Serving in Echelle Advisory Group & Future of ARCSAT Working Group (FAWG) of Apache Point Observatory
Comittee member of the astronomy white paper of Japan ( Astronomical Society of Japan, 2026 - )
Mission and International Teams
A Co-I member of the ESCAPE mission proposal submitted for the NASA Astrophysics SMEX call
A Co-I member of the JAXA's M-class mission candidate LAPYUTA
MAVEN EUVM team
A member of the ISSI workshop "Stellar Magnetism and its Impact on (Exo)Planets"
A young scientist member of ISSI team "Solar Extreme Events: Setting Up a Paradigm" led by Miyake F. (JP) & Usoskin I. (FI)
A young scientist member of ISSI team "The Role Of Solar And Stellar Energetic Particles On (Exo)Planetary Habitability (ETERNAL)" led by K. Herbst (DE) & J.L. Grenfell (DE)
A young scientist member of ISSI team "Quasi-periodic Pulsations in Stellar Flares: a Tool for Studying the Solar-Stellar Connection" led by Anne-Marie Broomhall (UK)
Conference & Workshop Organization
Local Organizing Committee of Cool Stars 23
Superflare Workshop 2016 at Kyoto University: "Superflares on Solar-type Stars and Solar Flares, and Their Impacts on Exoplanets and the Earth" (March 1st-4th, at Kyoto University) [LOC]
And many local meetings
Professional Memberships
2023- : American Geophysical Union (AGU)
2019 - : American Astronomical Society (AAS)
2019 - : AAS Solar Physics Division (SPD)
2014 - : Japan Solar Physics Community (JSPC)
2012 - : Astronomical Society of Japan (ASJ)