105 citations · 210 across the 18 of their papers we have counts for
20 papers
MIDSSAR: MId Dispersion Spectrograph for Stellar Activity Research
Fumihde Iwamuro, Daisaku Nogami, Hiroyuki Maehara +8
We have developed and commissioned MIDSSAR (MId Dispersion Spectrograph for Stellar Activity Research), a novel fiber-fed, dual-band spectrograph optimized for high-cadence monitor…
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…
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…
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…
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…
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…
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…
Sun-like stars produce superflares roughly once per century
Valeriy Vasilyev, Timo Reinhold, Alexander I. Shapiro +7
Stellar superflares are energetic outbursts of electromagnetic radiation, similar to solar flares but releasing more energy, up to erg on main sequence stars. It is unkno…
Evolution of Accretion Disk Structure of the Black Hole X-ray Binary MAXI J1820070 during the Rebrightening Phase
Tomohiro Yoshitake, Megumi Shidatsu, Yoshihiro Ueda +18
To understand the evolution of global accretion disk structure in the ``rebrightening'' phase of MAXI J1820070, we perform a comprehensive analysis of its near infrared/optical/…
Multiwavelength Observations of the Black Hole X-ray Binary MAXI J1820070 in the Rebrightening Phase
Tomohiro Yoshitake, Megumi Shidatsu, Yoshihiro Ueda +14
We report the results of quasi-simultaneous multiwavelength (near-infrared, optical, UV, and X-ray) observations of the Galactic X-ray black hole binary MAXI J1820+070 performed in…
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…
A long-duration superflare on the K giant HD 251108
Hans Moritz Günther, Dheeraj Pasham, Alexander Binks +10
Many giant stars are magnetically active, which causes rotational variability, chromospheric emission lines, and X-ray emission. Large outbursts in these emission features can set…
Multiwavelength observation of an active M-dwarf star EV Lac and its stellar flare accompanied by a delayed prominence eruption
Shun Inoue, Teruaki Enoto, Kosuke Namekata +9
We conducted 4-night multiwavelength observations of an active M-dwarf star EV Lac on 2022 October 2427 with simultaneous coverage of soft X-rays (NICER; 0.212 …
Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. I. Discovery of Prominence Eruptions Associated with Superflares
Kosuke Namekata, Vladimir S. Airapetian, Pascal Petit +14
Young solar-type stars frequently produce superflares, serving as a unique window into the young Sun-Earth environments. Large solar flares are closely linked to coronal mass eject…
APO & SMARTS flare star campaign observations I. Blue wing asymmetries in chromospheric lines during mid M dwarf flares from simultaneous spectroscopic and photometric observation data
Yuta Notsu, Adam F. Kowalski, Hiroyuki Maehara +12
We conducted the time-resolved simultaneous optical spectroscopic and photometric observations of mid M dwarf flare stars YZ CMi, EV Lac, and AD Leo. Spectroscopic observations wer…
Superflare occurrence and energies on G-, K- and M-type dwarfs
Simon Candelaresi, Andrew Hillier, Hiroyuki Maehara +2
Kepler data from G-, K- and M-type stars are used to study conditions that lead to superflares with energies above . From the 117,661 stars included, 380 show su…