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Damped Doppler shift oscillations have been observed in emission lines from ions formed at flare temperatures with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory and with the…

Astrophysics · Physics 2009-11-13 John T. Mariska , Harry P. Warren , David R. Williams , Tetsuya Watanabe

Solar flares, with energies ranging over several orders of magnitude, result from impulsive release of energy due to magnetic reconnection in the corona. Barring a handful, almost all microflares observed in X-rays are associated with the…

The EUV Imaging Spectrometer (EIS) on the Hinode satellite is capable of measuring emission line center positions for Gaussian line profiles to a fraction of a spectral pixel, resulting in relative solar Doppler-shift measurements with an…

Context. The corona of the Sun is the part of the solar atmosphere with temperatures of over one million Kelvin, which needs to be heated internally in order to exist. This heating mechanism remains a mystery; we see large magnetically…

Solar and Stellar Astrophysics · Physics 2023-11-03 I. Kraus , Ph. -A. Bourdin , J. Zender , M. Bergmann , A. Hanslmeier

The temperatures of the heavy ions ($T_i$) in the solar corona provide critical information about the heating mechanism of the million-degree corona. However, the measurement of $T_i$ is usually challenging due to the nonthermal motion,…

Solar and Stellar Astrophysics · Physics 2023-05-17 Yingjie Zhu , Judit Szente , Enrico Landi

Context: One of the most prominent processes suggested to heat the corona to well above 10^6 K builds on nanoflares, short bursts of energy dissipation. Aims: We compare observations to model predictions to test the validity of the…

Solar and Stellar Astrophysics · Physics 2015-11-04 Leping Li , Hardi Peter , Feng Chen , Jun Zhang

The solar atmosphere is filled with clusters of hot small-scale loops commonly known as Coronal Bright Points (CBPs). These ubiquitous structures stand out in the Sun by their strong X-ray and/or extreme-ultraviolet (EUV) emission for hours…

Solar and Stellar Astrophysics · Physics 2024-06-14 D. Nóbrega-Siverio , F. Moreno-Insertis , K Galsgaard , K. Krikova , L. Rouppe van der Voort , R. Joshi , M. S. Madjarska

Coronal holes are the source regions of the fast solar wind, which fills most of the solar system volume near the cycle minimum. Removing stray light from extreme ultraviolet (EUV) images of the Sun's corona is of high astrophysical…

Solar and Stellar Astrophysics · Physics 2013-02-05 Paul Shearer , Richard A. Frazin , Alfred O. Hero , Anna C. Gilbert

We present a Differential Emission Measure (DEM) analysis of the quiet solar corona on disk using data obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on {\it Hinode}. We show that the expected quiet Sun DEM distribution can…

Solar and Stellar Astrophysics · Physics 2009-11-09 David H. Brooks , Harry P. Warren , David R. Williams , Tetsuya Watanabe

A blowout jet occurred within the south coronal hole on 9 February 2011 at 09:00 UT and was observed by the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory, and the EUV…

Solar and Stellar Astrophysics · Physics 2015-06-17 Peter Young , Karin Muglach

We investigate the conditions under which small scale energy release events in the low corona gave rise to strong interplanetary (IP) type III bursts. We analyze observations of three tiny events, detected by the Nan\c cay Radio Heliograph…

Solar and Stellar Astrophysics · Physics 2015-10-07 C. E. Alissandrakis , A. Nindos , S. Patsourakos , A. Kontogeorgos , P. Tsitsipis

The X-ray and EUV emission of stars plays a key role in the loss and evolution of the atmospheres of their planets. The coronae of dwarf stars later than M6 appear to behave differently to those of earlier spectral types and are more X-ray…

Solar and Stellar Astrophysics · Physics 2020-05-06 Jeremy J. Drake , Vinay L. Kashyap , Bradford J. Wargelin , Scott J. Wolk

We present observations of transient active region heating events observed with the Extreme Ultraviolet Imaging Spectrometer (EIS) and X-ray Telescope (XRT) on Hinode. This initial investigation focuses on NOAA active region 10940 as…

Solar activity during 2007--2009 was very low, causing anomalously low thermospheric density. A comparison of solar extreme ultraviolet (EUV) irradiance in the He II spectral band (26 to 34 nm) from the Solar Extreme ultraviolet Monitor…

Solar and Stellar Astrophysics · Physics 2015-06-15 Leonid Didkovsky , Joseph B. Gurman

We present study of a typical explosive event (EE) at sub-arcsecond scale witnessed by strong non-Gaussian profiles with blue- and red-shifted emission of up to 150 km/s seen in the transition-region Si IV 1402.8 \AA, and the chromospheric…

Solar and Stellar Astrophysics · Physics 2015-06-23 Zhenghua Huang , Maria S. Madjarska , Lidong Xia , J. G. Doyle , Klaus Galsgaard , Hui Fu

We report quadrature observations of an extreme-ultraviolet (EUV) wave event on 2011 January 27 obtained by the Extreme Ultraviolet Imager (EUVI) onboard \emph{Solar Terrestrial Relations Observatory} (\emph{STEREO}), and the Atmospheric…

Solar and Stellar Astrophysics · Physics 2015-06-11 Y. Dai , M. D. Ding , P. F. Chen , J. Zhang

Small scale transients occur in the Solar corona at much higher frequencies than flares and play a significant role in coronal dynamics. Here we study three well-identified transients discovered by Hi-C and also detected by the EUV channels…

Solar and Stellar Astrophysics · Physics 2021-10-01 Abhishek Rajhans , Durgesh Tripathi , Vinay L. Kashyap

Small flares frequently occur in the quiet Sun. Previous studies have noted that they share many common characteristics with typical solar flares in active regions. However, their similarities and differences are not fully understood,…

Solar and Stellar Astrophysics · Physics 2023-05-03 Yuji Kotani , Takako T. Ishii , Daiki Yamasaki , Kenichi Otsuji , Kiyoshi Ichimoto , Ayumi Asai , Kazunari Shibata

The brightness temperature of the radio free-free emission at millimeter range is an effective tool for characterizing the vertical structure of the solar chromosphere. In this paper, we report on the first single-dish observation of a…

Solar and Stellar Astrophysics · Physics 2015-06-24 Kazumasa Iwai , Masumi Shimojo

The \textit{Sun Watcher using Active Pixel system detector and Image Processing}(SWAP) on board the \textit{PRoject for OnBoard Autonomy\todash 2} (PROBA\todash 2) spacecraft provides images of the solar corona in EUV channel centered at…

Solar and Stellar Astrophysics · Physics 2012-06-11 K. Chandrashekhar , S. Krishna Prasad , D. Banerjee , B. Ravindra , Daniel B. Seaton