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Coronal Holes (CHs) have subdued intensity and net blueshifts when compared to Quiet Sun (QS) at coronal temperatures. At transition region temperatures, such differences are obtained for regions with identical photospheric absolute…

Solar and Stellar Astrophysics · Physics 2021-11-30 Vishal Upendran , Durgesh Tripathi

We present three-dimensional astrochemical simulations and synthetic observations of magnetised, turbulent, self-gravitating molecular clouds. We explore various galactic interstellar medium environments, including cosmic-ray ionization…

Astrophysics of Galaxies · Physics 2021-01-20 Thomas G. Bisbas , Jonathan C. Tan , Kei E. I. Tanaka

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 analyze observations from the Interface Region Imaging Spectrograph of the Mg II k line, the Mg II UV subordinate lines, and the O I 135.6 nm line to better understand the solar plage chromosphere. We also make comparisons with…

Solar and Stellar Astrophysics · Physics 2015-08-21 Mats Carlsson , Jorrit Leenaarts , Bart De Pontieu

During a solar flare, it is believed that reconnection takes place in the corona followed by fast energy transport to the chromosphere. The resulting intense heating strongly disturbs the chromospheric structure, and induces complex…

Solar and Stellar Astrophysics · Physics 2019-04-30 Christopher M. J. Osborne , John A. Armstrong , Lyndsay Fletcher

Context. The contribution of quiet-Sun regions to the solar irradiance variability is currently unclear. Some solar-cycle variations of the quiet-Sun physical structure, such as the temperature gradient, might affect the irradiance. The…

Solar and Stellar Astrophysics · Physics 2018-09-05 M. Faurobert , M. Carbillet , L. Marquis , A. Chiavassa , G. Ricort

The Mg II h&k lines are powerful diagnostics for studying the solar chromosphere. They have become particularly popular with the launch of the IRIS satellite, and a number of studies that include these lines have lead to great progress in…

Solar and Stellar Astrophysics · Physics 2016-10-21 Jaime de la Cruz Rodríguez , Jorrit Leenaarts , Andrés Asensio Ramos

Surges are cool and dense ejections typically observed in chromospheric lines and closely related to other solar phenomena like UV bursts or coronal jets. Our aim is to address the current lack of inverted models and diagnostics of surges…

Solar and Stellar Astrophysics · Physics 2021-11-10 D. Nóbrega Siverio , S. L. Guglielmino , A. Sainz Dalda

Aims: We present observations from the Interface Region Imaging Spectrograph (IRIS) of absorption features from a multitude of cool atomic and molecular lines within the profiles of Si IV transition region lines. Many of these spectral…

Solar and Stellar Astrophysics · Physics 2015-06-22 Donald Schmit , Davina Innes , Thomas Ayres , Hardi Peter , Werner Curdt , Sarah Jaeggli

(Abridged) Aims: We characterize the dynamics of the quiet inter-network chromosphere by studying the occurrence of acoustic shocks and their relation with the concomitant photospheric structure and dynamics. Methods: We analyze a…

Astrophysics · Physics 2009-11-13 A. Vecchio , G. Cauzzi , K. P. Reardon

This paper shows the first synthetic tomography of the quiet solar chromosphere formed by spatial maps of scattering polarization. It has been calculated for the CaII 8498, 8542 and 3934 A lines by solving the NLTE (non-local…

Solar and Stellar Astrophysics · Physics 2015-06-23 E. S. Carlin , A Asensio Ramos

The evolution of the photospheric magnetic field plays a key role in the energy transport into the chromosphere and the corona. In active regions, newly emerging magnetic flux interacts with the pre-existent magnetic field, which can lead…

Solar and Stellar Astrophysics · Physics 2021-04-07 C. J. Díaz Baso , J. de la Cruz Rodríguez , J. Leenaarts

The solar chromosphere is a vigorously dynamic region of the sun, where waves and magnetic fields play an important role. To improve chromospheric diagnostics, we present new observations in Ca II 8542 carried out with the SST/CRISP on La…

Solar and Stellar Astrophysics · Physics 2015-03-14 Jaime de la Cruz Rodríguez , Hector Socas-Navarro , Michiel van Noort , Luc Rouppe van der Voort

We investigate the linear correlation coefficient between the intensities at different wavelengths in photospheric and chromospheric spectral lines. Waves that propagate vertically through the stratified solar atmosphere affect different…

Solar and Stellar Astrophysics · Physics 2015-05-14 C. Beck , W. Rammacher

The Mg II h&k emission lines (2803, 2796 A) are a useful tool for understanding stellar chromospheres and transition regions due to their intrinsic brightness, relatively low interstellar medium (ISM) absorption interference, and abundance…

Solar and Stellar Astrophysics · Physics 2024-03-21 Anna Taylor , Audrey Dunn , Sarah Peacock , Allison Youngblood , Seth Redfield

Context: Flux emergence in the solar atmosphere is a complex process that causes a release of magnetic energy as heat and acceleration of solar plasma at a variety of spatial scales. Methods: We analysed imaging spectropolarimetric data…

The Mg II h&k lines are amongst the best diagnostic tools of the upper solar chromosphere. This region of the atmosphere is of particular interest as it is the lowest region of the Sun's atmosphere where the magnetic field is dominant in…

Solar and Stellar Astrophysics · Physics 2023-03-01 Viggo Hansteen , Juan Martinez Sykora , Mats Carlsson , Bart De Pontieu , Milan Gosic , Souvik Bose

The heating and structure of the solar chromosphere depends on the underlying magnetic field, among other parameters. The lowest magnetic flux of the solar atmosphere is found in the quiet Sun internetwork and is thought to be provided by…

Solar and Stellar Astrophysics · Physics 2025-11-19 D. Przybylski , R. Cameron , S. K. Solanki , M. Rempel , S. Danilovic , J. Leenaarts

The O I 135.6 nm spectral line is formed in the chromosphere at the same heights as the Mg II h&k line cores are formed. As the O I line is optically thin, it represents a possibility for measuring the non-thermal velocities in this region…

Solar and Stellar Astrophysics · Physics 2026-05-05 Viggo Hansteen , Mats Carlsson , Bart De Pontieu , Daniel Nóbrega-Siverio

The convectively driven, weakly magnetized regions of the solar photosphere dominate the Sun's surface at any given time, but the temporal variations of these quiet regions of the photosphere throughout the solar cycle are still not well…

Solar and Stellar Astrophysics · Physics 2025-05-05 James Crowley , Ivan Milic , Gianna Cauzzi , Kevin Reardon