165 citations · 363 across the 10 of their papers we have counts for
11 papers
Discovery of a compact hierarchical triple main-sequence star system while searching for binary stars with compact objects
Ataru Tanikawa, Akito Tajitsu, Satoshi Honda +5
We have discovered a compact hierarchical triple main-sequence star system, which is cataloged as Gaia DR3 1010268155897156864 or TIC 21502513. Hereafter, we call it ``G1010''. G10…
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…
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…
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…
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 …
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 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…
Optical and Near-Infrared Polarimetry of Highly Reddened Type Ia Supernova 2014J: Peculiar Properties of Dust in M82
K. S. Kawabata, H. Akitaya, M. Yamanaka +46
We presented optical and near-infrared multi-band linear polarimetry of the highly reddened Type Ia SN~2014J appeared in M82. SN~2014J exhibits large polarization at shorter wavele…
High-dispersion spectroscopic monitoring of the Be/X-ray binary A0535+26/V725 Tau I: The long-term profile variability
Y. Moritani, D. Nogami, A. T. Okazaki +7
We report on optical high-dispersion spectroscopic monitoring observations of the Be/X-ray binary A0535+26/V725 Tau, carried out from November 2005 to March 2009. The main aim of t…
Early phase observations of extremely luminous Type Ia Supernova 2009dc
M. Yamanaka, K. S. Kawabata, K. Kinugasa +31
We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of the light curve is $Δm…