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Related papers: The RHESSI Microflare Height Distribution

200 papers

Wide-field high-precision photometric observations such as \textit{Transiting Exoplanet Survey Satellite (TESS)} allowed the investigation of the stellar magnetic activity of cool stars. M-dwarf's starspots and stellar flares are the main…

Solar and Stellar Astrophysics · Physics 2025-02-10 Rajib Kumbhakar , Soumen Mondal , Samrat Ghosh , Diya Ram

In June 2015, the Flat Spectrum Radio Quasar 3C 279 underwent an extremely bright gamma-ray flare, with an increase of the flux above 100 MeV by a factor 10 in less than 1 day, revealing an intrinsic variability timescale of 2 minutes as…

High Energy Astrophysical Phenomena · Physics 2019-08-14 C. Romoli , M. Zacharias , M. Meyer , F. Ait Benkhali , A. Jacholkowska , A. Wierzcholska , F. Jankowsky , J. P. Lenain

The Fermi Large Area Telescope (LAT) has been surveying the sky in gamma rays from 30 MeV to more than 300 GeV since August 2008. Fermi is the only mission able to detect high energy > few hundreds MeV emission from the Sun during the new…

High Energy Astrophysical Phenomena · Physics 2019-08-15 G. Iafrate , F. Longo

Recent measurements of vertical extents and positions of the chromospheric hard X-ray (HXR) flare sources based on Ramaty High-Energy Spectroscopic Imager (RHESSI) observations show a significant inconsistency with the theoretical…

Solar and Stellar Astrophysics · Physics 2016-12-07 Z. Moravec , M. Varady , J. Kasparova , D. Kramolis

We present a statistical analysis of properties of Soft X-Ray (SXR) emission, plasma temperature (T), and emission measure (EM), derived from GOES observations of flares in 2002-2017. The temperature and emission measures are obtained using…

Solar and Stellar Astrophysics · Physics 2019-03-27 Viacheslav M Sadykov , Alexander G Kosovichev , Irina N Kitiashvili , Alexander Frolov

Active region 11029 was a small, highly flare-productive solar active region observed at a time of extremely low solar activity. The region produced only small flares: the largest of the $>70$ Geostationary Observational Environmental…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. S. Wheatland

Nonthermal sources located above bright flare arcades, referred to as the "above-the-loop-top" sources, have been often suggested as the primary electron acceleration site in major solar flares. The X8.2 limb flare on 2017 September 10…

Solar and Stellar Astrophysics · Physics 2021-03-03 Bin Chen , Marina Battaglia , Säm Krucker , Katharine K. Reeves , Lindsay Glesener

We explore a technique for identifying the highest redshift (z>4) sources in Herschel/SPIRE and BLAST submillimeter surveys by localizing the position of the far-infrared dust peak. Just as Spitzer/IRAC was used to identify stellar `bump'…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Alexandra Pope , Ranga-Ram Chary

Fast Radio Bursts (FRBs) are energetic radio bursts that typically last for milliseconds. They are mostly of extragalactic origin, but the progenitors, trigger mechanisms and radiation processes are still largely unknown. Here we present a…

High Energy Astrophysical Phenomena · Physics 2025-12-03 Nurimangul Nurmamat , Yong-Feng Huang , Xiao-Fei Dong , Chen-Ran Hu , Orkash Amat , Ze-Cheng Zou , Abdusattar Kurban , Jin-Jun Geng , Chen Deng

This work reports the first discovery of (negative) spectral lags in the X-ray emission below 10 keV from the gamma ray binary $LSI +61^{o} $ 303 during large flaring episodes using the Rossi X-ray Timing Explorer (RXTE) observations. It is…

High Energy Astrophysical Phenomena · Physics 2016-07-13 Tamal Sarkar , Samir K Sarkar , Arunava Bhadra

Solar hard X-rays (HXRs) appear in the form of either footpoint sources or coronal sources, and each individual source provides its own critical information on acceleration of nonthermal electrons and plasma heating. Earlier studies found…

Solar and Stellar Astrophysics · Physics 2019-06-11 Hao Ning , Yao Chen , Jeongwoo Lee , Zhao Wu , Yang Su , Xiang-Liang Kong

The analysis of narrowband drifting of type III-like structures in radio bursts dynamic spectra allows to obtain unique information about primary energy release mechanisms in solar flares. The SSRT spatially resolved images and a high…

Solar and Stellar Astrophysics · Physics 2015-06-05 N. S. Meshalkina , A. T. Altyntsev , D. A. Zhdanov , S. V. Lesovoi , A. A. Kochanov , Yan Yihua , Tan Chengming

In this paper we analyze soft and hard X-ray emission of the 2002 September 20 M1.8 GOES class solar flare observed by RHESSI and GOES satellites. In this flare event, soft X-ray emission precedes the onset of the main bulk hard X-ray…

Solar and Stellar Astrophysics · Physics 2014-11-20 M. Siarkowski , R. Falewicz , P. Rudawy

Understanding the physical processes that trigger solar flares is paramount to help with forecasting space weather and mitigating the effects on our technological infrastructure. A previously unknown phenomenon was recently identified in…

Recent discoveries of highly dispersed millisecond radio bursts by Thornton et al. in a survey with the Parkes radio telescope at 1.4 GHz point towards an emerging population of sources at cosmological distances whose origin is currently…

High Energy Astrophysical Phenomena · Physics 2015-06-16 D. R. Lorimer , A. Karastergiou , M. A. McLaughlin , S. Johnston

We report the first detection of >100 MeV gamma rays associated with a behind-the-limb solar flare, which presents a unique opportunity to probe the underlying physics of high-energy flare emission and particle acceleration. On 2013 October…

Solar and Stellar Astrophysics · Physics 2015-06-03 Melissa Pesce-Rollins , Nicola Omodei , Vahe' Petrosian , Wei Liu , Fatima Rubio da Costa , Alice Allafort , Qingrong Chen

One of the key processes associated with the "standard" flare model is chromospheric evaporation, a process where plasma heated to high temperatures by energy deposition at the flare footpoints is driven upwards into the corona. Despite…

After almost 4 years of operation, the two instruments onboard the Fermi Gamma-ray Space Telescope have shown that the number of gamma-ray bursts with high energy photon emission above 100 MeV cannot exceed roughly 9% of the total number of…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Carl W. Akerlof , WeiKang Zheng

We present direct evidence for the detection of the main energy release site in a non-eruptive solar flare, SOL2013-11-09T06:38UT. This GOES C2.7 event was characterised by two flaring ribbons and a compact, bright coronal source located…

Solar and Stellar Astrophysics · Physics 2015-05-06 Paulo J. A. Simões , David R. Graham , Lyndsay Fletcher

This Research Note is in response to the recent paper by S. M. Perriyil et al. (2026). They provide measurements of the time delay (delta t) between the hard X-ray and soft X-ray peak times for 96 flares observed with RHESSI and GOES. These…

Solar and Stellar Astrophysics · Physics 2026-04-07 Brian R. Dennis , Hugh Hudson , Joel Allred