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The 133.5 nm lines are important observables for the NASA/SMEX mission Interface Region Imaging Spectrograph (IRIS). To make 3D non-LTE radiative transfer computationally feasible it is crucial to have a model atom with as few levels as…

Solar and Stellar Astrophysics · Physics 2015-09-30 Bhavna Rathore , Mats Carlsson

I present a study of high-resolution time series of Ca II H images and Fe I 630.15 nm spectra taken with the Solar Optical Telescope on the Hinode spacecraft. There is excellent correspondence between the Ca II H and Fe I line core…

Solar and Stellar Astrophysics · Physics 2021-02-03 A. G. de Wijn

Short-lived (100s or less), sub-arcsec to a couple of arcsec size features of enhanced brightenings in the narrowband images at the $\mathrm{H_{2V}}$ and $\mathrm{K_{2V}}$ positions of the Ca II H and K lines in the quiet Sun are known as…

Solar and Stellar Astrophysics · Physics 2022-12-21 Harsh Mathur , Jayant Joshi , K. Nagaraju , Luc Rouppe van der Voort , Souvik Bose

The first spectroscopic observations of cool Mg II loops above the solar limb observed by NASA's Interface Region Imaging Spectrograph ({\it IRIS}; \cite{IRIS}) are presented. During the observation period IRIS is pointed off-limb allowing…

Solar and Stellar Astrophysics · Physics 2014-09-02 L. K. Harra , S. A. Matthews , D. M. Long , G. A. Doschek , B. De Pontieu

The Interface Region Imaging Spectrograph (IRIS) reveals small-scale rapid brightenings in the form of bright grains all over coronal holes and the quiet sun. These bright grains are seen with the IRIS 1330 \AA, 1400 \AA\ and 2796 \AA\…

A three-dimensional picture of the solar atmosphere's thermodynamics can be obtained by jointly analyzing multiple spectral lines that span many formation heights. In paper I, we found strong correlations between spectral shapes from a…

Solar and Stellar Astrophysics · Physics 2021-07-21 Brandon Panos , Lucia Kleint

We examine the hypothesis that plasma associated with "Type II" spicules is heated to coronal temperatures, and that the upward moving hot plasma constitutes a significant mass supply to the solar corona. 1D hydrodynamical models including…

Solar and Stellar Astrophysics · Physics 2015-06-03 Philip G. Judge , Bart de Pontieu , Scott McIntosh , Kosovare Olluri

The Mg II h&k lines are the prime chromospheric diagnostics of NASA's Interface Region Imaging Spectrograph (IRIS). In the previous papers of this series we used a realistic three-dimensional radiative magnetohydrodynamics model to…

Solar and Stellar Astrophysics · Physics 2013-11-21 Tiago M. D. Pereira , Jorrit Leenaarts , Bart De Pontieu , Mats Carlsson , Han Uitenbroek

We investigate the statistics of the intensity distributions as function of the wavelength for Ca II H and the CA II IR line at 854.2 nm to estimate the energy content. We derived the intensity variations at different heights of the solar…

Solar and Stellar Astrophysics · Physics 2013-03-14 C. Beck , R. Rezaei , K. G. Puschmann

We recently reported extremely rapid changes in chromospheric fine structure observed using the IBIS instrument in the red wing of H alpha. Here, we examine data obtained during the same observing run (August 7 2010), of a mature active…

Solar and Stellar Astrophysics · Physics 2015-06-18 Isabel Lipartito , Philip Judge , Kevin Reardon , Gianna Cauzzi

We succeeded in observing two large spicules simultaneously with the Atacama Large Millimeter/submillimeter Array (ALMA), the Interface Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly (AIA) onboard the Solar…

The resonance lines of \ion{Si}{4} formed at $\lambda$1394 and 1403 {\AA} are the most critical for the diagnostics of the solar transition region in the observations of the Interface Region Imaging Spectrograph (IRIS). Studying the…

Solar and Stellar Astrophysics · Physics 2020-05-20 Durgesh Tripathi , V. N. Nived , Hiroaki Isobe , J. G. Doyle

Narrowband bursts (spikes) appear on dynamic spectra from microwave to decametric frequencies. They are believed to be manifestations of small-scale energy release through magnetic reconnection. We study the position of the spike-like…

Solar and Stellar Astrophysics · Physics 2022-03-30 S. Armatas , C. Bouratzis , A. Hillaris , C. E. Alissandrakis , P. Preka-Papadema , A. Kontogeorgos , P. Tsitsipis , X. Moussas

The structure and energy balance of the solar chromosphere remain poorly known. We have used the imaging spectrometer IBIS at the Dunn Solar Telescope to obtain fast-cadence, multi-wavelength profile sampling of Halpha and Ca II 854.2 nm…

Solar and Stellar Astrophysics · Physics 2015-05-13 G. Cauzzi , K. P. Reardon , R. J. Rutten , A. Tritschler , H. Uitenbroek

The type II spicule has been speculated to provide enough hot plasma to play an important role in the mass loading and heating of the corona. We analyse the disc counterpart to type II spicules, RBEs, in three high quality datasets from…

Solar and Stellar Astrophysics · Physics 2015-06-12 D. H. Sekse , L. Rouppe van der Voort , B. De Pontieu

The Interface Region Imaging Spectrograph (IRIS) reveals numerous small-scale (sub-arcsecond) brightenings that appear as bright dots sparkling the solar transition region in active regions. Here, we report a statistical study on these…

Solar and Stellar Astrophysics · Physics 2018-03-23 Zhenyong Hou , Zhenghua Huang , Lidong Xia , Bo Li , Maria S. Madjarska , Hui Fu

We present observations of a solar quiet region obtained using Hinode Solar Optical telescope (SOT) in Ca II H line with broadband filter taken on November 2006. We study offlimb and on disk spicules to find a counterpart of limb spicule on…

Solar and Stellar Astrophysics · Physics 2015-06-19 Ehsan Tavabi

The solar atmosphere was traditionally represented with a simple one-dimensional model. Over the past few decades, this paradigm shifted for the chromosphere and corona that constitute the outer atmosphere, which is now considered a dynamic…

Context. In the upper atmosphere of the Sun observations show convincing evidence for crossing and twisted structures, which are interpreted as mutual helicity and self-helicity. Aims. We use observations with the new Interface Region…

Solar and Stellar Astrophysics · Physics 2014-10-29 Leping Li , Hardi Peter , Feng Chen , Jun Zhang

Broad-band images of the solar chromosphere in the Ca II H&K line cores around active regions are covered with fine bright elongated structures called bright fibrils. The mechanisms that form these structures and cause them to appear bright…

Solar and Stellar Astrophysics · Physics 2020-05-06 Sepideh Kianfar , Jorrit Leenaarts , Sanja Danilovic , Jaime de la Cruz Rodríguez , Carlos José Díaz Baso