105 citations · 312 across the 12 of their papers we have counts for
14 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…
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…
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…
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…
Calcium bright knots and the formation of chromospheric anemone jets on the Sun
Kunwar Alkendra Pratap Singh, Keisuke Nishida, Kazunari Shibata
Space-based observations show that the solar atmosphere from the solar chromosphere to the solar corona is filled with small-scale jets and is linked with small-scale explosions. T…
Simple Model for Temporal Variations of H Spectrum by an Eruptive Filament from a Superflare on a Solar-type Star
Kai Ikuta, Kazunari Shibata
Flares are intense explosions on the solar and stellar surfaces, and solar flares are sometimes accompanied by filament or prominence eruptions. Recently, a large filament eruption…
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…
Starspot mapping with adaptive parallel tempering. II. Application to TESS data for M-dwarf flare stars, AU Microscopii, YZ Canis Minoris, and EV Lacertae
Kai Ikuta, Kosuke Namekata, Yuta Notsu +5
Starspots and stellar flares are indicators of stellar magnetic activity.The magnetic energy stored around spots is thought to be the origin of flares, but the connection is not co…
A Superflare on YZ Canis Minoris Observed by Seimei Telescope and TESS: Red Asymmetry of H Emission Associated with White-Light Emission
Keiichi Namizaki, Kosuke Namekata, Hiroyuki Maehara +4
Active M-type stars are known to often produce superflares on the surface. Radiation from stellar (super-)flares is important for the exoplanet habitability, but the mechanisms are…
Starspot activity and superflares on solar-type stars
Hiroyuki Maehara, Yuta Notsu, Shota Notsu +5
We analyze the correlation between starspots and superflares on solar-type stars using observations from the Kepler mission. The analysis shows that the observed fraction of stars…
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…