Yuta Notsu Adam F. Kowalski Hiroyuki Maehara Kosuke Namekata Kenji Hamaguchi Teruaki Enoto Isaiah I. Tristan Suzanne L. Hawley James R. A. Davenport Satoshi Honda Kai Ikuta Shun Inoue Keiichi Namizaki Daisaku Nogami Kazunari Shibata
The Astrophysical Journal 961(2) 189-189 2024年1月
Abstract
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 were obtained using Apache Point Observatory 3.5 m and Smal...
Kai Ikuta Kosuke Namekata Yuta Notsu Hiroyuki Maehara Soshi Okamoto Satoshi Honda Daisaku Nogami Kazunari Shibata
The Astrophysical Journal 948(1) 64-64 2023年5月 [査読有り]
Abstract
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 completely understood. To investigate the relation betwee...
The Astrophysical Journal 948(1) 9-9 2023年4月 [査読有り]
Abstract
Stellar coronal mass ejections (CMEs) have recently received much attention for their impacts on exoplanets and stellar evolution. Detecting prominence eruptions, the initial phase of CMEs, as the blueshifted excess component of Balmer ...
The Astrophysical Journal 945(1) 61-61 2023年3月 [査読有り]
<jats:title>Abstract</jats:title>
<jats:p>Active M-type stars are known to often produce superflares on the surface. Radiation from stellar (super)flares is important for exoplanet habitability, but the mechanisms are not well understood. In this...
Haining Li Wako Aoki Tadafumi Matsuno Qianfan Xing Takuma Suda Nozomu Tominaga Yuqin Chen Satoshi Honda Miho N. Ishigaki Jianrong Shi Jingkun Zhao Gang Zhao
The Astrophysical Journal 931(2) 147-147 2022年6月 [査読有り]
Abstract
We present homogeneous abundance analysis of over 20 elements for 385 very metal-poor (VMP) stars based on the LAMOST survey and follow-up observations with the Subaru Telescope. It is the largest high-resolution VMP sample (including 3...
Kai Ikuta Hiroyuki Maehara Yuta Notsu Kosuke Namekata Taichi Kato Shota Notsu Soshi Okamoto Satoshi Honda Daisaku Nogami Kazunari Shibata
The Astrophysical Journal 902(1) 73-73 2020年8月
Starspots are thought to be regions of locally strong magnetic fields,
similar to sunspots, and they can generate photometric brightness modulations.
To deduce stellar and spot properties, such as spot emergence and decay rates,
we implement compu...
Kosuke Namekata Hiroyuki Maehara Ryo Sasaki Hiroki Kawai Yuta Notsu Adam F. Kowalski Joel C. Allred Wataru Iwakiri Yohko Tsuboi Katsuhiro L. Murata Masafumi Niwano Kazuki Shiraishi Ryo Adachi Kota Iida Motoki Oeda Satoshi Honda Miyako Tozuka Noriyuki Katoh Hiroki Onozato Soshi Okamoto Keisuke Isogai Mariko Kimura Naoto Kojiguchi Yasuyuki Wakamatsu Yusuke Tampo Daisaku Nogami Kazunari Shibata
Publications of the Astronomical Society of Japan 72(4) 2020年5月
We report multi-wavelength monitoring observations of an M-dwarf flare star
AD Leonis with Seimei Telescope (6150--7930 {\AA}), SCAT (Spectroscopic
Chuo-university Astronomical Telescope; 3700--7500 {\AA}), NICER (Neutron Star
Interior Composition...
It has been occasionally suggested that Fe abundances of K dwarfs derived
from Fe I and Fe II lines show considerable discrepancies and oxygen abundances
determined from high-excitation O I 7771-5 triplet lines are appreciably
overestimated (the p...
Kosuke Namekata James R. A. Davenport Brett M. Morris Suzanne L. Hawley Hiroyuki Maehara Yuta Notsu Shin Toriumi Kai Ikuta Shota Notsu Satoshi Honda Daisaku Nogami Kazunari Shibata
ASTROPHYSICAL JOURNAL 891(2) 2020年2月
Star spot evolution is visible evidence of the emergence/decay of the
magnetic field on stellar surface, and it is therefore important for the
understanding of the underlying stellar dynamo and consequential stellar
flares. In this paper, we repor...
An extensive spectroscopic study on \xi Boo A (chromospherically active
solar-type star) was conducted based on the spectra obtained in 2008 December
though 2010 May, with an aim to detect any spectrum variability and to
understand its physical or...
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