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We present an overview of K2 short cadence observations for 34 M dwarfs observed in Campaigns 1 - 9 which have spectral types between M0 - L1. All of the stars in our sample showed flares with the most energetic reaching $3\times10^{34}$…

Solar and Stellar Astrophysics · Physics 2019-03-06 Lauren Doyle , Gavin Ramsay , John G. Doyle

We study the decay phase of solar flares in several spectral bands using a method based on that successfully applied to white light flares observed on an M4 dwarf. We selected and processed 102 events detected in the Sun-as-a-star flux…

Solar and Stellar Astrophysics · Physics 2021-02-10 Larisa K. Kashapova , Anne-Marie Broomhall , Alena I. Larionova , Elena G. Kupriyanova , Ilya D. Motyk

Filaments are very common physical phenomena on the Sun and are often taken as important proxies of solar magnetic activities. The study of filaments has become a hot topic in the space weather research. For a more comprehensive…

A large sample of over 38,000 chromospherically active candidate solar-like stars and cooler dwarfs from the RAVE survey is addressed in this paper. An improved activity identification with respect to the previous study was introduced to…

Using the observations from the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO), we investigate six X-class and twenty-nine M-class flares occurring in solar active…

Solar and Stellar Astrophysics · Physics 2015-08-06 Huadong Chen , Jun Zhang , Suli Ma , Shuhong Yang , Leping Li , Xin Huang , Junmin Xiao

We have compiled a catalog of optically-selected quasars with simultaneous observations in UV/optical and X-ray bands by the Swift Gamma Ray Burst Explorer. Objects in this catalog are identified by matching the Swift pointings with the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Jian Wu , Daniel Vanden Berk , Dirk Grupe , Scott Koch , Jonathan Gelbord , Donald P. Schneider , Caryl Gronwall , Sarah Wesolowski , Blair L. Porterfield

The light curves of solar-type stars present both periodic fluctuation and flare spikes. The gradual periodic fluctuation is interpreted as the rotational modulation of magnetic features on the stellar surface and is used to deduce magnetic…

Solar and Stellar Astrophysics · Physics 2018-05-15 Han He , Huaning Wang , Mei Zhang , Ahmad Mehrabi , Yan Yan , Duo Yun

Coronal mass ejection (CME) often produces a soft X-ray (SXR) flare associated with the low-coronal reconnection and a type-II radio burst associated with an interplanetary (IP) CME-shock. SXR flares and type-II bursts outshine the…

Solar and Stellar Astrophysics · Physics 2024-10-02 Atul Mohan , Nat Gopalswamy , Hemapriya Raju , Sachiko Akiyama

In previous works we have developed a method to convert solar X-ray data, collected with the Yohkoh/SXT, into templates of stellar coronal observations. Here we apply the method to several solar flares, for comparison with stellar X-ray…

Astrophysics · Physics 2009-11-06 F. Reale , G. Peres , S. Orlando

Since the launch of NASA's Solar Dynamics Observatory on 2010 February 11, the Extreme ultraviolet Variability Experiment (EVE) has observed numerous flares. One interesting feature observed by EVE is that a subset of flares exhibit an…

Solar and Stellar Astrophysics · Physics 2012-02-23 R. A. Hock , T. N. Woods , J. A. Klimchuk , F. G. Eparvier , A. R. Jones

We investigate the X-ray and UV emission detected by RHESSI and TRACE in the context of a solar flare on the 16th November 2002 with the goal of better understanding the evolution of the flare. We analysed the characteristics of the X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-11 Hamish A. S. Reid , Nicole Vilmer , Guillaume Aulanier , Etienne Pariat

The radio, optical, and $\gamma$-ray light curves of the blazar S5 1803+784, from the beginning of the {\it Fermi} Large Area Telescope (LAT) mission in August 2008 until December 2018, are presented. The aim of this work is to look for…

High Energy Astrophysical Phenomena · Physics 2021-03-03 R. Nesci , S. Cutini , C. Stanghellini , F. Martinelli , A. Maselli , V. M. Lipunov , V. Kornilov , R. R. Lopez , A. Siviero , M. Giroletti , M. Orienti

There is a wide range of eruptions in the solar atmosphere which contribute to space weather, including the major explosions of radiation known as flares. To examine pre-event behavior in delta-spot regions, we use here a method based on…

Solar and Stellar Astrophysics · Physics 2019-01-21 Marianna B. Korsos , Shuhong Yang , Robert Erdelyi

The spot evolution on the Sun and solar-type stars is important for understanding the nature of consequential flaring activity. This study statistically investigates the variance of flare occurrence rate through the time evolution of spots…

Solar and Stellar Astrophysics · Physics 2025-05-23 Takato Tokuno , Kosuke Namekata , Hiroyuki Maehara , Shin Toriumi

Solar flares are known to leave imprints on the magnetic field at the photosphere, often manifested as an abrupt and permanent change in the downward-directed Lorentz force in localized areas inside the active region. Our study aims to…

Solar and Stellar Astrophysics · Physics 2026-04-16 Samriddhi Sankar Maity , Ranadeep Sarkar , Piyali Chatterjee , Nandita Srivastava

Sequences of line-of-sight (LOS) magnetograms recorded by the Michelson-Doppler Imager are used to quantitatively characterize photospheric magnetic structure and evolution in three active regions that rotated across the Sun's disk during…

Solar and Stellar Astrophysics · Physics 2015-05-27 B. T. Welsch , S. Christe , J. M. McTiernan

Previous studies have shown that the energy release mechanism of some solar flares follow the Standard magnetic-reconnection model, but the detailed properties of high-energy electrons produced in the flare are still not well understood. We…

Solar and Stellar Astrophysics · Physics 2015-07-15 Natsuha Kuroda , Haimin Wang , Dale E. Gary

We study five sequential solar flares (SOL2015-08-07) occurring in Active Region 12396 observed with the Goode Solar Telescope (GST) at the BBSO, complemented by IRIS and SDO observations. The main flaring region is an arch filament system…

Solar and Stellar Astrophysics · Physics 2018-03-19 Yingna Su , Rui Liu , Shangwei Li , Wenda Cao , Kwangsu Ahn , Haisheng Ji

Kanzelh\"ohe Observatory (KSO) regularly performs high-cadence full-disk imaging of the solar chromosphere in the H$\alpha$ and CaIIK spectrallines as well as the solar photosphere in white-light. In the frame of ESA's Space Situational…

The High Altitude Water Cherenkov (HAWC) Observatory recently began full-scale operations, surveying 2/3 of the entire sky at very high energy (VHE; E > 100 GeV). This new view of the sky offers the opportunity to detect flares from…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Thomas Weisgarber