Results 61 to 70 of about 2,393 (171)

S5 1803+78 Revisited

Acta Polytechnica, 2012
We report on our optical monitoring of the BL Lac object S5 1803+78 from 1996 to 2011. The source showed no clear periodicity, but a time scale of about 1 300 days between major flares is possibly present. No systematic trend of the color index with flux
R. Nesci, A. Maselli, F. Montagni, S. Sclavi   +3 more
doaj  

Rising Near-ultraviolet Spectra in Stellar Megaflares

The Astrophysical Journal
Flares from M dwarf stars can attain energies up to 10 ^4 times larger than solar flares but are generally thought to result from similar processes of magnetic energy release and particle acceleration.
Adam F. Kowalski, Rachel A. Osten, Yuta Notsu, Isaiah I. Tristan, Antigona Segura, Hiroyuki Maehara, Kosuke Namekata, Shun Inoue   +7 more
doaj   +1 more source

A Statistical Study of Soft X-Ray Flares on Solar-type Stars

The Astrophysical Journal
The statistical characteristics of stellar flares at optical bands have received extensive study, but they remain to be studied at soft X-ray bands, in particular for solar-type stars.
Z. H. Zhao, Z. Q. Hua, X. Cheng, Z. Y. Li, M. D. Ding   +4 more
doaj   +1 more source

Beam electrons as a source of Hα flare ribbons

Nature Communications, 2017
The dynamic of plasma heating in solar flares can be effectively derived from observations of optical hydrogen H-α line emissions. Here the authors report the observation of a C1.5 class flare that produced two H-α ribbons, interpreted combining ...
Malcolm Druett, Eamon Scullion, Valentina Zharkova, Sarah Matthews, Sergei Zharkov, Luc Rouppe Van der Voort   +5 more
doaj   +1 more source

The Unluckiest Star: A Spectroscopically Confirmed Repeated Partial Tidal Disruption Event AT 2022dbl

The Astrophysical Journal Letters
The unluckiest star orbits a supermassive black hole elliptically. Every time it reaches the pericenter, it shallowly enters the tidal radius and gets partially tidally disrupted, producing a series of flares.
Zheyu Lin, Ning Jiang, Tinggui Wang, Xu Kong, Dongyue Li, Han He, Yibo Wang, Jiazheng Zhu, Wentao Li, Ji-an Jiang, Avinash Singh, Rishabh Singh Teja, D. K. Sahu, Chichuan Jin, Keiichi Maeda, Shifeng Huang   +15 more
doaj   +1 more source

Optical flares and flaring oscillations on the M-type eclipsing binary CU Cnc

, 2012
It will be published in ...
-B., Qian S., Zhang, J., Zhu, L. -Y., Liu, L., Liao, W. -P., Zhao, E. -G., He, J. -J., Li, L. -J., Li, K., Dai, Z. -B.   +9 more
openaire   +2 more sources

Scalable, Advanced Machine Learning Based Approaches for Stellar Flare Identification: Application to TESS Short-cadence Data and Analysis of a New Flare Catalog

The Astronomical Journal
We apply multialgorithm machine learning models to TESS 2 minute survey data from Sectors 1–72 to identify stellar flares. Models trained with deep neural network, random forest, and XGBoost algorithms utilize four flare light-curve characteristics as ...
Chia-Lung Lin, Dániel Apai, Mark S. Giampapa, Wing-Huen Ip   +3 more
doaj   +1 more source

Tracing the Light: Identification for the Optical Counterpart Candidates of Binary Black Holes during O3

The Astrophysical Journal
The accretion disks of active galactic nuclei (AGN) are widely considered the ideal environments for binary black hole mergers and the only plausible sites for their electromagnetic counterparts. M. J. Graham et al.
Lei He, Zhengyan Liu, Rui Niu, Bingzhou Gao, Mingshen Zhou, Purun Zou, Runduo Liang, Wen Zhao, Ning Jiang, Zhen-Yi Cai, Zi-Gao Dai, Ye-Fei Yuan   +11 more
doaj   +1 more source

AT2022sxl: A Candidate Repeating Tidal Disruption Event in Possible Association with Two High-energy Neutrino Events

The Astrophysical Journal
We report a candidate repeating tidal disruption event (TDE), AT2022sxl, found from large-field optical survey data. Two flares with a separation time of ∼7.2 yr between the two optical peaks are observed.
Shunhao Ji, Zhongxiang Wang, Litao Zhu, Stefan Geier, Alok C. Gupta   +4 more
doaj   +1 more source

Repeating flares, X-ray outbursts and delayed infrared emission: A comprehensive compilation of optical tidal disruption events

Astronomy & Astrophysics
Tidal disruption events (TDEs) have been proposed as valuable laboratories for studying dormant black holes. However, progress in this field has been hampered by the limited number of observed events.
Langis D. A., Liodakis I., Koljonen K. I. I., Paggi A., Globus N., Wyrzykowski L., Mikołajczyk P. J., Kotysz K., Zieliński P., Ihanec N., Ding J., Morshed D., Torres Z.   +12 more
doaj   +1 more source