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Recent observations suggest that magnetic flux cancellation may play a crucial role in heating the Sun's upper atmosphere (chromosphere, transition region, corona). Here, we intended to validate an analytic model for magnetic reconnection…

Solar and Stellar Astrophysics · Physics 2020-07-08 Sung-Hong Park

SDO/AIA images the full solar disk in several EUV bands that are each sensitive to coronal plasma emissions of one or more specific temperatures. We observe that when isolated active regions (ARs) are on the disk, full-disk images in some…

Solar and Stellar Astrophysics · Physics 2021-03-10 Talwinder Singh , Alphonse C. Sterling , Ronald L. Moore

Certain solar flares exhibit a distinctive candle-flame or cusp-shaped feature above the bright flare arcade visible in extreme ultraviolet (EUV) and X-ray channels sensitive to high-temperature plasma. The presence of a cusp-like structure…

Solar and Stellar Astrophysics · Physics 2026-05-19 Ivan Oparin , Sabastian Fernandes , Bin Chen , Chengcai Shen , Xiaocan Li , Fan Guo , Sijie Yu

We analyze coordinated Hinode XRT and EIS observations of a non-flaring active region to investigate the thermal properties of coronal plasma taking advantage of the complementary diagnostics provided by the two instruments. In particular…

Solar and Stellar Astrophysics · Physics 2015-05-20 Paola Testa , Fabio Reale , Enrico Landi , Ed DeLuca , Vinay Kashyap

In this study, we investigate motions in the hot plasma above the flare loops during the 2017 September 10 X8.2 flare event. We examine the region to the south of the main flare arcade, where there is data from the Interface Region Imaging…

Solar and Stellar Astrophysics · Physics 2021-01-06 Katharine K. Reeves , Vanessa Polito , Bin Chen , Giselle Galan , Sijie Yu , Wei Liu , Gang Li

We follow the eruption of two related intermediate filaments observed in H$\alpha$ (from GONG) and in EUV (from SDO/AIA) and the resulting large-amplitude longitudinal oscillations of the plasma in the filament channels. The events occurred…

Solar and Stellar Astrophysics · Physics 2017-12-13 M. Luna , Y. Su , B. Schmieder , R. Chandra , T. A. Kucera

Surges have regularly been observed mostly in H$_{\alpha}$ 6563~{\AA} and Ca~{\sc ii} 8542~{\AA}. However, surge$'$s response to other prominent lines of the interface-region (Mg~{\sc ii} k 2796.35~{\AA} $\&$ h 2803.52~{\AA}, O~{\sc iv}…

Solar and Stellar Astrophysics · Physics 2021-07-07 Pradeep Kayshap , Rajdeep Singh Payal , Sharad C. Tripathi , Harihara Padhy

We present the results of combined NH3(1,1) and (2,2) line emission observed with the Very Large Array and the Effelsberg 100m telescope of the Infrared Dark Cloud G14.225-0.506. The NH3 emission reveals a network of filaments constituting…

With the observations of SDO/AIA 304 {\AA} and NVST H{\alpha} bands, we present the formation process of an active-region filament in active region NOAA 11903 during the period from 02:00 UT to 10:00 UT on November 25, 2013. A series of…

Solar and Stellar Astrophysics · Physics 2019-08-14 Jincheng Wang , Xiaoli Yan , 2Qiaoling Guo , 3Defang Kong , Zhike Xue , Liheng Yang , Qiaoling Li

Quasi-periodic intensity disturbances propagating upward along the coronal structure have been extensively studied using EUV imaging observations from SOHO/EIT and TRACE. They were interpreted as either slow mode magnetoacoustic waves or…

Solar and Stellar Astrophysics · Physics 2012-01-26 Tongjiang Wang , Leon Ofman , Joseph M. Davila

Observational measurements of active region emission measures contain clues to the time-dependence of the underlying heating mechanism. A strongly non-linear scaling of the emission measure with temperature indicates a large amount of hot…

Solar and Stellar Astrophysics · Physics 2015-06-11 Stephen J. Bradshaw , James A. Klimchuk , Jeffrey W. Reep

We observed a C-class flare at the outer boundary of the super-penumbra of a sunspot. The flare was triggered by an emerging magnetic bipolar region that was obliquely oriented with respect to the super-penumbral fibrils. The flare started…

Solar and Stellar Astrophysics · Physics 2018-10-17 S. Liu , H. Q. Zhang , D. P. Choudhary , A. K. Srivastava , B. N. Dwivedi

We explore the general properties of near-surface flows around solar active regions. Helioseismic holography is applied to HMI Dopplergrams yielding nearly 5000 flow measurements of 336 unique active regions observed by the Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2019-03-20 D. C. Braun

In this paper we introduce a new diagnostic technique that uses prominence EUV and UV absorption to determine the prominence plasma electron temperature and column emission measure, as well as He/H relative abundance; if a realistic…

Solar and Stellar Astrophysics · Physics 2015-06-11 E. Landi , F. Reale

Extreme-ultraviolet (EUV) waves are one of the large-scale phenomena on the Sun. They are defined as large propagating fronts in the low corona with speeds ranging from a few tens km/s to a multiple of 1000 km/s. They are often associated…

Solar and Stellar Astrophysics · Physics 2023-10-20 Ramesh Chandra , Pooja Devi , P. F. Chen , Brigitte Schmieder , Reetika Joshi , Bhuwan Joshi , Arun Kumar Awasthi

In this paper, we present the imaging and spectroscopic observations of the simultaneous horizontal and vertical large-amplitude oscillation of a quiescent filament triggered by an EUV wave on 2022 October 02. Particularly, the filament…

Solar and Stellar Astrophysics · Physics 2023-10-31 Jun Dai , Qingmin Zhang , Ye Qiu , Chuan Li , Zhentong Li , Shuting Li , Yingna Su , Haisheng Ji

With the SDO/AIA instrument, continuous and intermittent plasma outflows are observed on the boundaries of an active region along two distinct open coronal loops. %with the speed of 30$\sim$200 km s$^{-1}$. By investigating the temporal…

Solar and Stellar Astrophysics · Physics 2014-05-16 S. Liu , J. T. Su

Plasma processes occurring in the corona and solar wind can be probed by studying the thermodynamic properties of different ion species. However, most in-situ observations of positive ions in the solar wind are taken at 1 AU, where…

Space Physics · Physics 2019-03-06 D. Stansby , D. Perrone , L. Matteini , T. S. Horbury , C. S. Salem

The identification of large numbers of localised transient EUV brightenings, with small spatial scales, in the quiet-Sun corona has been one of the key early results from Solar Orbiter. However, much is still unknown about these events.…

Diffuse far-ultraviolet (FUV) emissions from the Lupus Loop region (SNR 330.0+15.0) have been observed with Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR), also known as Far-ultraviolet IMaging Spectrograph (FIMS). We…