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Emerging flux regions (EFRs) are known to exhibit various sporadic local heating events in the lower atmosphere. To investigate the characteristics of these events, especially to link the photospheric magnetic fields and atmospheric…

Solar and Stellar Astrophysics · Physics 2017-02-15 Shin Toriumi , Yukio Katsukawa , Mark C. M. Cheung

The interaction between emerging active regions and the pre-existing coronal magnetic field is important to understand better the mechanisms of storage and release of magnetic energy from the convection zone to the high corona. We are…

Solar and Stellar Astrophysics · Physics 2015-06-05 S. Regnier

Ubiquitous small-scale vortices have recently been found in the lower atmosphere of the quiet Sun in state-of-the-art solar observations and in numerical simulations. We investigate the characteristics and temporal evolution of a…

Solar and Stellar Astrophysics · Physics 2016-01-27 S. -H. Park , G. Tsiropoula , I. Kontogiannis , K. Tziotziou , E. Scullion , J. G. Doyle

Using multiwavelength imaging observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) on 03 May 2012, we present a novel physical scenario for the formation of a temporary X-point in the solar…

Solar and Stellar Astrophysics · Physics 2020-01-08 A. K. Srivastava , Sudheer K. Mishra , P. Jelínek , Tanmoy Samanta , Hui Tian , Vaibhav Pant , P. Kayshap , D. Banerjee , J. G. Doyle , B. N. Dwivedi

Active regions (ARs) appear in the solar atmosphere as a consequence of the emergence of magnetic flux-ropes (FR). In this study, we use Bayesian methods to analyze line-of-sight magnetograms of emerging ARs. We employ a FR model consisting…

Solar and Stellar Astrophysics · Physics 2024-05-21 Mariano Poisson , Marcelo López Fuentes , Cristina H. Mandrini , Pascal Démoulin , Francisco Grings

Since the discovery of quasi-periodic propagating oscillations with periods of order three to ten minutes in coronal loops with TRACE and EIT (later with EUVI and EIS), they have been almost universally interpreted as evidence for…

Solar and Stellar Astrophysics · Physics 2015-05-19 Bart De Pontieu , Scott W. McIntosh

Solar flares are rapid energy release phenomena that appear as bright ribbons in the chromosphere and high-temperature loops in the corona, respectively. Supra-arcade Downflows (SADs) are plasma voids that first come out above the flare…

Solar and Stellar Astrophysics · Physics 2021-07-21 Z. F. Li , X. Cheng , M. D. Ding , Katharine K. Reeves , DeOndre Kittrell , Mark Weber , David E. McKenzie

Persistent outflows have recently been detected at boundaries of some active regions. Although these outflows are suggested to be possible sources of the slow solar wind, the nature of these outflows is poorly understood. Through an…

Solar and Stellar Astrophysics · Physics 2015-05-19 L. -J. Guo , H. Tian , J. -S. He

Stellar flares are characterized by sudden enhancement of electromagnetic radiation from the atmospheres of stars. Compared to their solar counterparts, our knowledge on the coronal plasma dynamics of stellar flares and their connection to…

Solar and Stellar Astrophysics · Physics 2022-07-20 Hechao Chen , Hui Tian , Hao Li , Jianguo Wang , Hongpeng Lu , Yu Xu , Zhenyong Hou , Yuchuan Wu

Aims. We aim to infer information about the magnetic field in the low solar corona from coronal rain clumps using high-resolution spectropolarimetric observations in the Ca ii 8542 A line obtained with the Swedish 1-m Solar Telescope.…

Solar and Stellar Astrophysics · Physics 2021-06-09 M. Kriginsky , R. Oliver , P. Antolin , D. Kuridze , N. Freij

We investigated how the magnetic field in solar active regions (ARs) controls flare activity, i.e., whether a confined or eruptive flare occurs. We analyzed 44 flares of GOES class M5.0 and larger that occurred during 2011--2015. We used 3D…

Solar and Stellar Astrophysics · Physics 2018-02-14 Christian Baumgartner , Julia K. Thalmann , Astrid M. Veronig

We investigate the plasma and magnetic environment of active region NOAA 11261 on 2 August 2011 around a GOES M1.4 flare/CME (SOL2011-08-02T06:19). We compare coronal emission at (extreme) ultraviolet and X-ray wavelengths, using SDO AIA…

Solar and Stellar Astrophysics · Physics 2016-08-03 Julia K. Thalmann , Astrid M. Veronig , Yang Su

Studying Doppler shifts provides deeper insights into the flow of mass and energy in the solar atmosphere. We perform a comprehensive measurement of Doppler shifts in the transition region and its center-to-limb variation (CLV) in the…

Solar and Stellar Astrophysics · Physics 2023-03-01 Abhishek Rajhans , Durgesh Tripathi , Vinay L. Kashyap , James A. Klimchuk , Avyarthana Ghosh

We use images of high spatial, spectral and temporal resolution, obtained using both ground- and space-based instrumentation, to investigate the coupling between wave phenomena observed at numerous heights in the solar atmosphere. Intensity…

Solar and Stellar Astrophysics · Physics 2015-06-11 D. B. Jess , I. De Moortel , M. Mathioudakis , D. J. Christian , K. P. Reardon , P. H. Keys , F. P. Keenan

We study a series of X-ray-bright, rapidly-evolving active-region coronal jets outside the leading sunspot of AR 12259, using Hinode/XRT, SDO/AIA and HMI, and IRIS data. The detailed evolution of such rapidly evolving "violent" jets…

Solar and Stellar Astrophysics · Physics 2017-07-26 Alphonse C. Sterling , Ronald L. Moore , David A. Falconer , Navdeep K. Panesar , Francisco Martinez

We investigate the evolution of coronal loop emission in the context of the coronal magnetic field topology. New modeling techniques allow us to investigate the magnetic field structure and energy release in active regions. Using these…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. -Y. Lee , Graham Barnes , K. D. Leka , Katharine K. Reeves , K. E. Korreck , L. Golub , E. E. DeLuca

Solar active regions (ARs) are thought to be formed by magnetic fields from the convection zone. Our flux emergence simulations revealed that a strong horizontal divergent flow (HDF) of unmagnetized plasma appears at the photosphere before…

Solar and Stellar Astrophysics · Physics 2015-06-22 Shin Toriumi , Keiji Hayashi , Takaaki Yokoyama

We studied the formation of a pore in AR NOAA 11462. We analysed data obtained with the IBIS at the DST on April 17, 2012, consisting of full Stokes measurements of the Fe I 617.3 nm lines. Furthermore, we analysed SDO/HMI observations in…

Solar and Stellar Astrophysics · Physics 2017-01-24 I. Ermolli , A. Cristaldi , F. Giorgi , F. Giannattasio , M. Stangalini , P. Romano , A. Tritschler , F. Zuccarello

We analyze data from the Solar and Heliospheric Observatory to produce global maps of coronal outflow velocities and densities in the regions where the solar wind is undergoing acceleration. The maps use UV and white light coronal data…

Solar and Stellar Astrophysics · Physics 2015-06-03 Leonard Strachan , Alexander V. Panasyuk , John L. Kohl , Philippe Lamy

We report the discovery and characterization of high-speed (>100 km/s) horizontal flows in solar active regions, making use of the Sun-as-a-star spectroscopy in the range 5-105 nm provided by the EVE (Extreme Ultraviolet Variability…