Zobrazeno 1 - 10
of 72
pro vyhledávání: '"Kosuke Namekata"'
Publikováno v:
The Astrophysical Journal, Vol 965, Iss 2, p 170 (2024)
Thermal microwave emissions detected from stellar atmospheres contain information on stellar activity. However, even for the Sun, the relationship between multifrequency microwave data and other activity indices remains unclear. We investigated the r
Externí odkaz:
https://doaj.org/article/d2ae2d3d84224a23bef63e2ec4ec2061
Autor:
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
Publikováno v:
The Astrophysical Journal, Vol 961, Iss 2, p 189 (2024)
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 Small and Moderate
Externí odkaz:
https://doaj.org/article/f5c6d27694c84a49bf8bb9ee21fe127c
Autor:
Kosuke Namekata, Vladimir S. Airapetian, Pascal Petit, Hiroyuki Maehara, Kai Ikuta, Shun Inoue, Yuta Notsu, Rishi R. Paudel, Zaven Arzoumanian, Antoaneta A. Avramova-Boncheva, Keith Gendreau, Sandra V. Jeffers, Stephen Marsden, Julien Morin, Coralie Neiner, Aline A. Vidotto, Kazunari Shibata
Publikováno v:
The Astrophysical Journal, Vol 961, Iss 1, p 23 (2024)
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 ejections (CMEs) associated with filament/prominence eruptions, but observa
Externí odkaz:
https://doaj.org/article/30d269fbbff04ea8bedbe27316345f0f
Autor:
Hisashi Hayakawa, Sabrina Bechet, Frédéric Clette, Hugh S. Hudson, Hiroyuki Maehara, Kosuke Namekata, Yuta Notsu
Publikováno v:
The Astrophysical Journal Letters, Vol 954, Iss 1, p L3 (2023)
The Carrington flare in 1859 September is a benchmark, as the earliest reported solar flare and as an event with one of the greatest terrestrial impacts. To date, no rigorous estimate of the energy of this flare has been made on the basis of the only
Externí odkaz:
https://doaj.org/article/e9064065014a4fe0b43198d8ee2d5f0e
Autor:
Kai Ikuta, Kosuke Namekata, Yuta Notsu, Hiroyuki Maehara, Soshi Okamoto, Satoshi Honda, Daisaku Nogami, Kazunari Shibata
Publikováno v:
The Astrophysical Journal, Vol 948, Iss 1, p 64 (2023)
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 between spot locatio
Externí odkaz:
https://doaj.org/article/8353a31bf3e54a8e9d59f517b32f0ac9
Autor:
Shun Inoue, Hiroyuki Maehara, Yuta Notsu, Kosuke Namekata, Satoshi Honda, Keiichi Namizaki, Daisaku Nogami, Kazunari Shibata
Publikováno v:
The Astrophysical Journal, Vol 948, Iss 1, p 9 (2023)
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 lines is a tec
Externí odkaz:
https://doaj.org/article/111d0966a0f84e22a1fedb9084c0c765
Autor:
Keiichi Namizaki, Kosuke Namekata, Hiroyuki Maehara, Yuta Notsu, Satoshi Honda, Daisaku Nogami, Kazunari Shibata
Publikováno v:
The Astrophysical Journal, Vol 945, Iss 1, p 61 (2023)
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 paper, we report simultaneous optical spectro
Externí odkaz:
https://doaj.org/article/02671677cf674e30abb4a573b63d80c1
Autor:
Kosuke Namekata, Shin Toriumi, Vladimir S. Airapetian, Munehito Shoda, Kyoko Watanabe, Yuta Notsu
Publikováno v:
The Astrophysical Journal, Vol 945, Iss 2, p 147 (2023)
The Kepler space telescope and Transiting Exoplanet Survey Satellite unveiled that Sun-like stars frequently host exoplanets. These exoplanets are subject to fluxes of ionizing radiation in the form of X-ray and extreme-ultraviolet (EUV) radiation th
Externí odkaz:
https://doaj.org/article/294c58d6ba604fd6a1332330599340b7
Autor:
Keiichi Namizaki, Kosuke Namekata, Hiroyuki Maehara, Yuta Notsu, Satoshi Honda, Daisaku Nogami, Kazunari Shibata
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 not well understood. In this paper, we report simultaneous optical sp
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::531f158ecb5488bf8aaa86a52d954739
http://arxiv.org/abs/2302.03007
http://arxiv.org/abs/2302.03007
Autor:
Kosuke Namekata, Hiroyuki Maehara, Satoshi Honda, Yuta Notsu, Soshi Okamoto, Jun Takahashi, Masaki Takayama, Tomohito Ohshima, Tomoki Saito, Noriyuki Katoh, Miyako Tozuka, Katsuhiro L. Murata, Futa Ogawa, Masafumi Niwano, Ryo Adachi, Motoki Oeda, Kazuki Shiraishi, Keisuke Isogai, Daikichi Seki, Takako T. Ishii, Kiyoshi Ichimoto, Daisaku Nogami, Kazunari Shibata
Publikováno v:
Nature Astronomy. 6:241-248
Solar flares are often accompanied by filament/prominence eruptions (~10⁴ K and ~10¹⁰⁻¹¹ cm⁻³), sometimes leading to coronal mass ejections that directly affect the Earth’s environment. ‘Superflares’ are found on some active solar-t
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b5f82d400918cd720ce869cb912dc73f
https://doi.org/10.1038/s41550-021-01532-8
https://doi.org/10.1038/s41550-021-01532-8