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Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close to the coronal Alfv\'{e}n speed. Yet, spectroscopic…

Solar and Stellar Astrophysics · Physics 2014-12-02 Hui Tian , Gang Li , Katharine K. Reeves , John C. Raymond , Fan Guo , Wei Liu , Bin Chen , Nicholas A. Murphy

High resolution spectral observations of transition region spectral lines capture the signatures of energy deposition and redistribution at the boundary between the lower and upper atmosphere, and have significant relevance for…

Solar and Stellar Astrophysics · Physics 2026-05-06 Paola Testa , Bart De Pontieu , Kyuhyoun Cho , Thomas Ayres

Based on observations from the EUV Imaging Spectrometer (EIS) on board Hinode, the existence of a broad distribution of blue and red Dopplershift in active region loops has been revealed; the distribution of Dopplershifts depends on the…

Solar and Stellar Astrophysics · Physics 2017-06-07 S. Regnier , R. W. Walsh

We analyse sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the…

Solar and Stellar Astrophysics · Physics 2015-06-23 Vasyl Yurchyshyn , Valentyna Abramenko , Ali Kilcik

The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, and corona with 0.33-0.4 arcsec spatial resolution, 2 s temporal…

Results from the Solar Maximum Mission showed a close connection between the hard X-ray and transition region emission in solar flares. Analogously, the modern combination of RHESSI and IRIS data can inform the details of heating processes…

Solar and Stellar Astrophysics · Physics 2016-08-31 Jeffrey W. Reep , Harry P. Warren , Nicholas A. Crump , Paulo J. A. Simoes

This study analyzed the Doppler shift in the solar spectrum using the Interface Region Imaging Spectrograph (IRIS). Two types of oscillations were investigated: long period damp and short period damp. The researchers observed periodic…

Solar and Stellar Astrophysics · Physics 2024-12-25 E. Tavabi , R. Sadeghi

Coronal rain corresponds to cool and dense clumps in the corona accreting towards the solar surface, and is often observed above solar active regions. They are generally thought to be produced by thermal instability in the corona and their…

Solar and Stellar Astrophysics · Physics 2020-04-15 Ryohtaroh T. Ishikawa , Yukio Katsukawa , Patrick Antolin , Shin Toriumi

The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H I Lyman-{\alpha} during a suborbital rocket flight on September 3, 2015. The Interface Region Imaging Telescope (IRIS) coordinated with the CLASP observations…

We present the results of a set of three-dimensional numerical simulations of magnetic flux emergence from below the photosphere into the corona that include a uniform and horizontal coronal magnetic field mimicking a pre-existing…

Astrophysics · Physics 2009-11-10 K. Galsgaard , F. Moreno-Insertis , V. Archontis , A. Hood

Magnetic reconnection at the interface between coronal holes and loops, so-called interchange reconnection, can release the hotter, denser plasma from magnetically confined regions into the heliosphere, contributing to the formation of the…

Solar and Stellar Astrophysics · Physics 2015-03-13 A. F. Rappazzo , W. H. Matthaeus , D. Ruffolo , S. Servidio , M. Velli

Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models, as well as their description of…

Solar and Stellar Astrophysics · Physics 2016-01-13 N. B. Orange , D. L. Chesny , H. M. Oluseyi , K. Hesterly , M. Patel , P. R. Champey

The EUI instrument on the Solar Orbiter spacecraft has obtained the most stable, high-resolution images of the solar corona from its orbit with a perihelion near 0.4 AU. A sequence of 360 images obtained at 17.1 nm, between 25-Oct-2022…

Solar and Stellar Astrophysics · Physics 2023-09-12 Philip G. Judge

Over the last two decades the uninterrupted, high-resolution observations of the Sun, from the excellent range of telescopes aboard many spacecraft complemented with observations from sophisticated ground-based telescopes have opened up a…

Solar and Stellar Astrophysics · Physics 2015-06-05 G. Tsiropoula , K. Tziotziou , I. Kontogiannis , M. S. Madjarska , J. G. Doyle , Y. Suematsu

Granular convective motions reach into the lower solar atmosphere, typically causing photospheric spectral lines to exhibit a differential line shift. This Doppler shift to shorter wavelength is commonly known as convective blueshift. We…

Solar and Stellar Astrophysics · Physics 2019-01-30 Franziska Stief , Johannes Löhner-Böttcher , Wolfgang Schmidt , Tilo Steinmetz , Ronald Holzwarth

Solar jets, collimated plasma ejections driven by magnetic reconnection, play a vital role in energy transport and coronal heating. While rotational motions in jets are often attributed to magnetic field untwisting, alternative explanatory…

Solar and Stellar Astrophysics · Physics 2026-02-25 Lei Huang , Yang Guo , Zhen Li , Jinhan Guo , Mingde Ding

Understanding the nature and evolution of the photospheric helicity flux transfer is a key to reveal the role of magnetic helicity in coronal dynamics of solar active regions. Using SDO/HMI photospheric vector magnetograms and the derived…

Solar and Stellar Astrophysics · Physics 2017-01-11 P. Vemareddy , P. Démoulin

Here, we present several examples of unusual evolutionary patterns in solar coronal loops that resemble cross-field drift motions. These loops were simultaneously observed from two vantage points by two different spacecraft: the…

Solar and Stellar Astrophysics · Physics 2025-05-28 Sudip Mandal , Hardi Peter , James A. Klimchuk , Lakshmi Pradeep Chitta

Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations…

Solar and Stellar Astrophysics · Physics 2009-07-22 Harry P. Warren , David H. Brooks

The heating of the solar corona and the puzzle of the slender high reaching magnetic loops seen in observations from the Transition Region And Coronal Explorer(TRACE) has been investigated through 3D numerical simulations, and found to be…

Astrophysics · Physics 2007-05-23 Boris V. Gudiksen , Aake Nordlund