Results 51 to 60 of about 2,393 (171)

A Superflare on YZ Canis Minoris Observed by the Seimei Telescope and TESS: Red Asymmetry of Hα Emission Associated with White-light Emission

The Astrophysical Journal, 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.
Keiichi Namizaki, Kosuke Namekata, Hiroyuki Maehara, Yuta Notsu, Satoshi Honda, Daisaku Nogami, Kazunari Shibata   +6 more
doaj   +1 more source

Optical and EUV observations of solar flare kernels [PDF]

Astronomy & Astrophysics, 2005
We present high-resolution spectral observations, covering the entire optical region (3800−9000 A), of a solar flare observed during a multiwavelength campaign. The flare, recorded on 2002 January 11, was a medium solar flare event (GOES class C7.5).
García-Alvarez, D., Johns-Krull, C., Doyle, J., Ugarte-Urra, I., Madjarska, M., Butler, C.   +5 more
openaire   +2 more sources

ABOUT THE FLASHES’ ACTIVITY OF AO535+26 IN OPTICAL BAND

Odessa Astronomical Publications, 2017
After the great multipulse outburst of Oct. 1995 (JD 2450019) was recorded we followed the optical activity of Be/neutron star binary system A0535+26. The  information on optical flares during 25 years of photoelectric observations was replenished by the
N. I. Dorokhov, T. N. Dorokhova, Yu. V. Beletskiy   +2 more
doaj   +1 more source

Shock Cooling and Breakout Emission for Optical Flares Associated with Gravitational-wave Events

The Astrophysical Journal
The astrophysical origin of stellar-mass black hole (BH) mergers discovered through gravitational waves (GWs) is widely debated. Mergers in the disks of active galactic nuclei (AGNs) represent promising environments for at least a fraction of these ...
Hiromichi Tagawa, Shigeo S Kimura, Zoltán Haiman, Rosalba Perna, Imre Bartos   +4 more
doaj   +1 more source

Magnetic Field Amplification and Blazar Flares

EPJ Web of Conferences, 2013
Recent multiwavelength observations of PKS 0208-512 by SMARTS, Fermi, and Swift revealed that γ-ray and optical light curves of this flat spectrum radio quasars are highly correlated, but with an exception of one large optical flare having no ...
Chen Xuhui, Chatterjee Ritaban, Fossati Giovanni, Pohl Martin   +3 more
doaj   +1 more source

AT 2019aalc: A Bowen Fluorescence Flare with a Precursor Flare in an Active Galactic Nucleus

The Astrophysical Journal
AT 2019aalc is a peculiar sequence of highly variable emission events observed towards the nucleus of the broad-line active galactic nucleus (AGN) SDSS J152416.66+045119.0.
Marzena Śniegowska, Benny Trakhtenbrot, Lydia Makrygianni, Iair Arcavi, Claudio Ricci, Sara Faris, Biswaraj Palit, D. Andrew Howell, Megan Newsome, Joseph Farah, Curtis McCully, Estefania Padilla-Gonzalez, Giacomo Terreran   +12 more
doaj   +1 more source

A circular white-light flare with impulsive and gradual white-light kernels

Nature Communications, 2017
White-light flares are rare solar events entailing emission in the optical continuum. Here, the authors report a nearly circular white-light flare observed on March 10th 2015 that contains simultaneously both impulsive and gradual white-light kernels.
Q. Hao, K. Yang, X. Cheng, Y. Guo, C. Fang, M. D. Ding, P. F. Chen, Z. Li   +7 more
doaj   +1 more source

Optical variability of the blazar 3C 454.3 during 2007-2010

EPJ Web of Conferences, 2013
The optical variability of the blazar 3C 454.3 during 2007-2010 has been studied using the results of multicolor (BVRIJHK) observations. The existence of two variable synchrotron sources was found.
Hagen-Thorn V.A., Larionov V.M., Arkharov A.A., Hagen-Thorn E.I., Blinov D.A.   +4 more
doaj   +1 more source

Polarization and Spectral Energy Distribution in OJ 287 during the 2016/17 Outbursts

Galaxies, 2017
We report optical photometric and polarimetric observations of the blazar OJ 287 gathered during 2016/17. The high level of activity, noticed after the General Relativity Centenary flare, is argued to be part of the follow-up flares that exhibited high ...
Mauri Valtonen, Stanislaw Zola, Helen Jermak, Stefano Ciprini, Rene Hudec, Lankeswar Dey, Achamveedu Gopakumar, Daniel L. Reichart, Daniel B. Caton, Kosmas Gazeas, Katsura Matsumoto, Waldemar Ogloza, Marek Drozdz, Fahri Alicavus, Oleksandr Baransky, Andrei Berdyugin, Panos Boumis, Yurii Bufan, Bartlomiej Debski, Huseyin Er, Ahmet Erdem, Vira Godunova, Shirin Haque, Vivian L. Hoette, Jan Janik, Mark Kidger, Tomasz Kundera, Sebastian Kurowski, Alexis Liakos, Isa Mohammed, Kari Nilsson, Urszula Pajdosz, Vilppu Piirola, Tapio Pursimo, Brandon Rajkumar, Andrii O. Simon, Michal Siwak, Eda Sonbas, Ian A. Steele, Volodymir V. Vasylenko, Michal Zejmo, Pawel Zielinski   +41 more
doaj   +1 more source

FUMES. IV. Optical and Far-ultraviolet Spectra of a Flare on the M Dwarf GJ 4334

The Astronomical Journal
On 2017 September 20, we observed GJ 4334, an M5V dwarf rotating with a period of 23.5 days, simultaneously with both the Space Telescope Imaging Spectrograph aboard Hubble (1160–1710 Å) and the Dual Imaging Spectrograph mounted on the 3.5 m telescope at
Girish M. Duvvuri, J. Sebastian Pineda, Aylin García Soto, Zachory K. Berta-Thompson, Allison Youngblood, Kevin France, Elisabeth R. Newton, Keivan G. Stassun   +7 more
doaj   +1 more source