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Searches for exoplanets with radial velocity techniques are increasingly sensitive to stellar activity. It is therefore crucial to characterize how this activity influences radial velocity measurements in their study of the detectability of…

Solar and Stellar Astrophysics · Physics 2015-05-19 Nadège Meunier , Anne-Marie Lagrange , Morgan Desort

Analysis of INTEGRAL/IBIS survey observations has revealed that the rare intermediate polar and asynchronous polar cataclysmic variables are consistently found to emit in the 20-100 keV energy band, whereas synchronous polars and the common…

Astrophysics · Physics 2009-11-11 E. J. Barlow , C. Knigge , A. J. Bird , A. J. Dean , D. J. Clark , A. B. Hill , M. Molina , V. Sguera

Waves have long been thought to contribute to the heating of the solar corona and the generation of the solar wind. Recent observations have demonstrated evidence of quasi-periodic longitudinal disturbances and ubiquitous transverse wave…

Solar and Stellar Astrophysics · Physics 2015-06-16 J. Threlfall , I. De Moortel , S. W. McIntosh , C. Bethge

Low-amplitude Doppler-shift oscillations have been observed in coronal emission lines in a number of active regions with the EUV Imaging Spectrometer (EIS) on the Hinode satellite. Both standing and propagating waves have been detected and…

Solar and Stellar Astrophysics · Physics 2015-05-18 John T. Mariska , K. Muglach

Plages are small concentrations of strong, nearly vertical magnetic fields in the solar photosphere that expand with height. A high spatial and spectral resolution that can resolve their fine structure is required to characterize them, and…

Solar and Stellar Astrophysics · Physics 2025-05-13 G. Liu , I. Milić , J. S. Castellanos Duran , J. M. Borrero , M. van Noort , C. Kuckein

For the first time, we present and discuss EUV radiances of the solar transition region (TR) and corona obtained during a solar cycle. The measurements were obtained with the SOHO/coronal diagnostic spectrometer (CDS) during the period from…

Solar and Stellar Astrophysics · Physics 2017-03-30 V. Andretta , G. Del Zanna

The Mg II h&k doublet are two of the primary spectral lines observed by the Sun-pointing Interface Region Imaging Spectrograph (IRIS). These lines are tracers of the magnetic and thermal environment that spans from the photosphere to the…

Solar and Stellar Astrophysics · Physics 2015-10-07 Donald Schmit , Paul Bryans , Bart De Pontieu , Scott McIntosh , Jorrit Leenaarts , Mats Carlsson

Oscillations of coronal loops in the Sun have been reported in both imaging and spectral observations at the onset of flares. Images reveal transverse oscillations, whereas spectra detect line-of-sight velocity or Doppler-shift…

Solar and Stellar Astrophysics · Physics 2015-05-27 Danica Tothova , Davina Innes , Guillermo Stenborg

Oscillations were observed across the whole solar disk using the Doppler shift and line depth of spectral lines from the CO molecule near 4666~nm with the National Solar Observatory's McMath/Pierce solar telescope. Power, coherence, and…

Solar and Stellar Astrophysics · Physics 2015-05-20 Matthew Penn , Tom Schad , Erin Cox

A statistical study has been carried out of the relationship between plasma flow Doppler velocities and magnetic field parameters during the emergence of active regions at the solar photospheric level with data acquired by the Michelson…

Solar and Stellar Astrophysics · Physics 2017-05-01 A. Khlystova

Alfven waves and ion-cyclotron absorption of high-frequency waves are frequently brought into models devoted to coronal heating and fast solar-wind acceleration. Signatures of ion-cyclotron resonance have already been observed in situ in…

Astrophysics · Physics 2009-11-13 L. Dolla , J. Solomon

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph (IRIS). The observations were made of a solar active region on 2015 December 18 as part of the…

Solar and Stellar Astrophysics · Physics 2017-08-30 T. S. Bastian , G. Chintzoglou , B. De Pontieu , M. Shimojo , D. Schmit , J. Leenaarts , M. Loukitcheva

Instabilities described by linear theory characterize an important form of wave-particle interaction in the solar wind. We diagnose unstable behavior of solar wind plasma between 0.3 and 1 au via the Nyquist criterion, applying it to fits…

Solar and Stellar Astrophysics · Physics 2021-12-22 Mihailo M. Martinovic , Kristopher G. Klein , Tereza Durovcova , Benjamin L. Alterman

Near the 10 solar radius perihelion of Parker Solar Probe encounter 24, a confined region containing an enhanced plasma density (25,000 per cubic centimeter) and broadband electrostatic waves was encountered. The solar wind velocity (200…

Space Physics · Physics 2026-02-24 Forrest Mozer , Oleksiy Agapitov , Kyungeun Choi , Andrii Voshchepynets

We report three-minute oscillations in the solar chromosphere driven by a strong downflow event in a sunspot. We used the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope and the Interface Region Imaging Spectrograph (IRIS).…

Solar and Stellar Astrophysics · Physics 2016-04-27 Hannah Kwak , Jongchul Chae , Donguk Song , Yeon-Han Kim , Eun-Kyung Lim , Maria S. Madjarska

The electron density is one of the crucial parameters in plasma plume, which plays a major role in producing the key reactive species required for biological and industrial applications. In this work, experiments are performed to estimate…

Plasma Physics · Physics 2018-10-23 G. Veda Prakash , Kiran Patel , Narayan Behera , Ajai Kumar

Recent in situ observations from Parker Solar Probe (PSP) near perihelia reveal ion beams, temperature anisotropies, and kinetic wave activity. These features are likely linked to solar wind heating and acceleration. During PSP Encounter 17…

We study the radiative emission of various types of solar features, such as quiet Sun, enhanced network, plage, and bright plage regions, identified on filtergrams taken in the Ca II K line. We analysed fulldisk images obtained with the…

Solar and Stellar Astrophysics · Physics 2015-05-19 I. Ermolli , S. Criscuoli , H. Uitenbroek , F. Giorgi , M. P. Rast , S. K. Solanki

We present observations of a solar plage in the millimeter-continuum with the ALMA and in the Ca 8542 and Na 5896 spectral lines with the Interferometric BIdimensional Spectrometer (IBIS). Our goal is to compare the measurement of local gas…

Solar and Stellar Astrophysics · Physics 2022-07-27 Ryan Hofmann , Kevin Reardon , Ivan Milic , Momchil Molnar , Yi Chai , Han Uitenbroek

The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. The unique combination of near and far-ultraviolet spectra and images at subarcsecond…