160 citations · 1.3k across the 51 of their papers we have counts for
57 papers
Coronal Mass Ejections from Young Suns: An Observational View through the Solar-Stellar Connection
Kosuke Namekata
Kepler and TESS have revealed that magnetically active stars frequently produce flares and superflares, raising the possibility that frequent, fast, and massive coronal mass ejecti…
Frequent X-class Far UV Flares from a Young Solar Analog DS Tucanae A
Tristen Sextro, Kevin France, Vladimir Airapetian +4
The young solar analog DS Tuc A (~45 million years old, spectral type G6V) serves as an excellent proxy to the Sun during early stages of the Earth's evolution. The young Sun's enh…
Systematic and Statistical Properties of Prominence Eruptions on the M-dwarf YZ CMi
Yuto Kajikiya, Kosuke Namekata, Yuta Notsu +4
M-dwarfs produce frequent flares, and their associated mass ejections are expected to significantly affect the habitability of close-in exoplanets. Recent spectroscopic observation…
Magnetic Heating Across the Sun and Solar-like Stars: Universal Scaling Laws from Chromospheres to Coronae
Shin Toriumi, Kosuke Namekata, Yuta Notsu +2
Magnetic activity in cool stars governs the thermal structure and high-energy radiative output of their outer atmospheres, thereby influencing stellar evolution, stellar winds, and…
Time-Resolved Connection between Starspots and Flares in Nearby Young Solar-type Stars Observed by TESS
Daijiro Hitotsuyanagi, Hiroto Yamada, Daisuke Yamashiki +3
Superflares are energetic explosions on stellar surface with energies of 10^33-10^36 erg, significantly exceeding those of typical solar flares. While previous studies have suggest…
Magnetic activity in cool stars: manifestations and relevance to exoplanets
E. Işık, A. Valio, A. Strugarek +10
Understanding stellar magnetic activity is central to exoplanet science in two ways: it sets the dynamic astrospheric boundary condition governing planetary space environments, and…
Stellar Forcing of (exo)Planetary Environments
Julián D. Alvarado-Gómez, Erika Palmerio, Manuel Güdel +13
The environments of exoplanets are fundamentally shaped by the magnetic activity of their host stars through radiative, plasma, and particle-driven processes. This article presents…
X-ray and Hα superflare on an RS CVn-type star, UX Arietis: Constraint on the flare location from radial velocity change during the flare
Sota Urabe, Yohko Tsuboi, Kosuke Namekata +5
We report on a giant stellar flare from the RS CVn-type binary UX Arietis, detected with the Monitor of All-sky X-ray Image (MAXI) and followed by a 12-day optical spectroscopic ca…
Spectral and photometric variability of SS 433 observed with XRISM and simultaneous optical and near-infrared telescopes
Yusuke Sakai, Shinya Yamada, Yuta Okada +36
We present results from coordinated multiwavelength observations of the SS 433, obtained with XRISM, optical telescopes, and near-infrared camera during 2024 April and 2025 March.…
Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. III. Comparison between Starspot Mapping, Zeeman Doppler Imaging, and Multiwavelength Variability
Kai Ikuta, Kosuke Namekata, Pascal Petit +12
Recent simultaneous multiwavelength observations of a nearby young solar-type star EK Dra in the optical, H spectrum, and X-ray, have provided evidence for stellar prominence er…
Doppler imaging combined with high-cadence photometry. I. Revisiting the surface of a pre-main-sequence flare star
Sanghee Lee, Engin Bahar, Hakan Volkan Şenavcı +11
Latitude distribution of stellar magnetic activity is not well constrained by observations, despite its importance for a better understanding of stellar dynamos. We aim to obtain a…
The Preliminary Mauve Science Programme: Science themes identified for the first year of operations
Mauve Science Collaboration, Marcel Agueros, Don Dixon +22
Mauve is a low-cost small satellite developed and operated by Blue Skies Space Ltd. The payload features a 13 cm telescope connected with a fibre that feeds into a UV-Vis spectrome…
The Exospace Weather Frontier
R. O. Parke Loyd, Evgenya L. Shkolnik, Joseph Lazio +26
Space weather is among the most powerful and least understood forces shaping planetary atmospheres. In our Solar System, we observe its effects directly: atmospheric escape, chemic…
Do Young Suns Produce Frequent, Massive CMEs? Results from Five-year Dedicated Optical Observations of EK Draconis and V889 Hercules
Kosuke Namekata, Hiroyuki Maehara, Yuta Notsu +4
We report results from a five-year (132-night) dedicated observational campaign targeting two nearby young solar-type stars, EK Draconis (50-125 Myr age) and V889 Hercules ($…
Discovery of multi-temperature coronal mass ejection signatures from a young solar analogue
Kosuke Namekata, Kevin France, Jongchul Chae +14
Coronal mass ejections (CMEs) on the early Sun may have profoundly influenced the planetary atmospheres of early Solar System planets. Flaring young solar analogues serve as excell…
Coronal Mass Ejections from Young Suns: Insights from Solar and Stellar Observations and Models
Kosuke Namekata
Recent discoveries have revealed exoplanets orbiting young Sun-like stars, offering a window into the early solar system. These young stars frequently produce extreme magnetic expl…
A Semi-Empirical Estimate of Solar EUV Evolution from 10 Myr to 10 Gyr
Kevin France, Girish Duvvuri, Cynthia Froning +9
The extreme-ultraviolet (EUV; 100 -- 911 Å) spectra of F, G, K, and M stars provide diagnostics of the stellar chromosphere through the corona, with line and continuum formation te…
Time evolution of white-light flare accompanied by probable postflare loops on M-type dwarf EV Lacertae
Shinnosuke Ichihara, Daisaku Nogami, Kosuke Namekata +6
White-light flares are explosive phenomena accompanied by brightening of continuum from near-ultraviolet to optical, which occur on the Sun and stars. In order to investigate the m…
Systematic NICER study of the low-ionized Fe K line on RS Canum Venaticorum type stars
Shun Inoue, Teruaki Enoto, Yuta Notsu +4
The Fe K fluorescence line ( keV) has been observed during solar and stellar flares. Two emission mechanisms of the Fe K line, photoionization and collisional ioniz…
Temporal Variation of Flare Occurrence Rates via the Spot Evolution on the Sun and Solar-type Stars
Takato Tokuno, Kosuke Namekata, Hiroyuki Maehara +1
The spot evolution on the Sun and solar-type stars is important for understanding the nature of consequential flaring activity. This study statistically investigates the variance o…
High-Time-Cadence Spectroscopy and Photometry of Stellar Flares on M-dwarf YZ Canis Minoris with Seimei Telescope and TESS. II. Statistical Properties of Blue/Red Asymmetries in the H Line
Yuto Kajikiya, Kosuke Namekata, Yuta Notsu +4
M-dwarfs frequently produce flares, and their associated coronal mass ejections (CMEs) may threaten the habitability of close-in exoplanets. M-dwarf flares sometimes show prominenc…
High-Time-Cadence Spectroscopy and Photometry of Stellar Flares on M-dwarf YZ Canis Minoris with Seimei Telescope and TESS. I. Discovery of Rapid and Short-Duration Prominence Eruptions
Yuto Kajikiya, Kosuke Namekata, Yuta Notsu +3
M-dwarfs show frequent flares and associated coronal mass ejections (CMEs) may significantly impact close-in habitable planets. M-dwarf flares sometimes show red/blue asymmetries i…
Rising Near-Ultraviolet Spectra in Stellar Megaflares
Adam F. Kowalski, Rachel A. Osten, Yuta Notsu +5
Flares from M-dwarf stars can attain energies up to times larger than solar flares but are generally thought to result from similar processes of magnetic energy release and…
Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. II. Understanding Prominence Eruption through Data-Driven Modeling and Observed Magnetic Environment
Kosuke Namekata, Kai Ikuta, Pascal Petit +15
EK Draconis, a nearby young solar-type star (G1.5V, 50-120 Myr), is known as one of the best proxies for inferring the environmental conditions of the young Sun. The star frequentl…