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We study extreme-ultraviolet emission line spectra derived from three-dimensional magnetohydrodynamic models of structures in the corona. In order to investigate the effects of increased magnetic activity at photospheric levels in a…

Solar and Stellar Astrophysics · Physics 2009-04-16 Pia Zacharias , Sven Bingert , Hardi Peter

The X-ray and EUV emission of stars plays a key role in the loss and evolution of the atmospheres of their planets. The coronae of dwarf stars later than M6 appear to behave differently to those of earlier spectral types and are more X-ray…

Solar and Stellar Astrophysics · Physics 2020-05-06 Jeremy J. Drake , Vinay L. Kashyap , Bradford J. Wargelin , Scott J. Wolk

Total eclipse observations were performed in 2008 and 2009 to study the He I and He II shells near the 1 Mm heights above the solar limb. They suggest that the corona penetrates deep into the chromosphere following magnetic chanels. Thanks…

Solar and Stellar Astrophysics · Physics 2010-08-04 Cyril Bazin , Serge Koutchmy , Ehsan Tavabi

Waves are thought to play a significant role in the heating of the solar atmosphere and the acceleration of the wind. Among the many types of waves observed in the Sun, the so-called p-modes with a 3 mHz frequency peak dominate the lower…

One of the outstanding problems in all of space science is uncovering how the solar corona is heated to temperatures greater than 1 MK. Though studied for decades, one of the major difficulties in solving this problem has been unraveling…

Solar and Stellar Astrophysics · Physics 2015-06-15 Nicholeen M. Viall , James A. Klimchuk

Measuring the global magnetic field of the solar corona remains exceptionally challenging. The fine-scale density structures observed in white light images taken during Total Solar Eclipses (TSEs) are currently the best proxy for inferring…

Solar and Stellar Astrophysics · Physics 2020-06-10 Benjamin Boe , Shadia Habbal , Miloslav Druckmuller

SECIS observations of the June 2001 total solar eclipse were taken using an Fe {\sc xiv} 5303 {\AA} filter. Automated tools based on wavelet analysis was used to detect intensity oscillations on various areas of the images. Statistical…

Astrophysics · Physics 2007-05-23 A. C. Katsiyannis , D. R. Williams , F. Murtagh , R. T. J. McAteer , F. P. Keenan

This paper reports the first full-Sun vacuum ultraviolet (VUV) emission line profile originating from the transition region from the chromosphere to the corona. It is based on a raster scan of the whole solar disk using SUMER/SOHO. The…

Astrophysics · Physics 2007-05-23 Hardi Peter

Why the tenuous solar outer atmosphere, or corona, is much hotter than the underlying layers remains one of the greatest challenge for solar modeling. Detailed diagnostics of the coronal thermal structure come from extreme ultraviolet (EUV)…

Solar and Stellar Astrophysics · Physics 2018-05-02 Gregory Fleishman , Sophie Musset , Véronique Bommier , Lindsay Glesener

The coronal green line (Fe XIV 5303 A) profiles were obtained from Fabry-Perot interferometric observations of the solar corona during the total solar eclipse of 21 June 2001 from Lusaka, Zambia. The instrumental width is about 0.2 A and…

Solar and Stellar Astrophysics · Physics 2015-05-28 K. P. Raju , T. Chandrasekhar , N. M. Ashok

The Extreme-ultraviolet Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) detects the solar EUV spectra with high temporal cadence and spectral resolution. The wavelength shifts of emission lines provide key…

Solar and Stellar Astrophysics · Physics 2021-04-21 Zhixun Cheng , Yuming Wang , Rui Liu

Variable super-strong coronal emission lines were observed in one galaxy, SDSS J095209.56+214313.3, and their origin remains controversy. In this paper, we report the detection of variable broad spectral bumps, reminiscent of supernova (SN)…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Ting-Gui Wang , Hongyan Zhou , Lifan Wang , Honglin Lu , Dawei Xu

A very slight rotation-induced latitudinal temperature variation (presumably on the order of several Kelvin) on the solar surface is theoretically expected. While recent high-precision solar brightness observations reported its detection,…

Solar and Stellar Astrophysics · Physics 2017-08-30 Y. Takeda , S. UeNo

Many competing models for the coronal heating and acceleration mechanisms of the high-speed solar wind depend on the solar magnetic field and plasma structure in the corona within heliocentric distances of $5R_\odot$. We report on sensitive…

Solar and Stellar Astrophysics · Physics 2015-06-16 Jason E. Kooi , Patrick D. Fischer , Jacob J. Buffo , Steven R. Spangler

The SphinX X-ray spectrophotometer on the {\em CORONAS-PHOTON}\/ mission observed the 1~--~15\,keV X-ray spectrum of the spatially integrated solar corona during the deep minimum of 2009, when solar activity was exceptionally low. Its…

Solar and Stellar Astrophysics · Physics 2020-01-08 B. Sylwester , J. Sylwester , M. Siarkowski , K. J. H. Phillips , P. Podgorski , M. Gryciuk

CONTEXT: Thermal emission from extrasolar planets makes it possible to study important physical processes in their atmospheres and derive more precise orbital elements. AIMS: By using new near infrared and optical data, we examine how these…

Earth and Planetary Astrophysics · Physics 2022-08-10 G. Kovacs , I. Dekany , B. Karamiqucham , G. Chen , G. Zhou , M. Rabus , T. Kovacs

The last solar minimum has been unusually quiet compared to the previous minima (since space-based radiometric measurements are available). The Sun's magnetic flux was substantially lower during this minimum. Some studies also show that the…

Solar and Stellar Astrophysics · Physics 2015-09-02 F. Shakeri , L. Teriaca , S. K. Solanki

Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present…

Solar and Stellar Astrophysics · Physics 2016-09-28 Michael Hahn , Daniel Wolf Savin

The ROSAT PSPC pulse height spectrum of the peculiar He-rich hot white dwarf KPD 0005+5106 provided a great surprise when first analysed by Fleming, Werner & Barstow (1993). It defied the best non-LTE modelling attempts in terms of…

Astrophysics · Physics 2009-11-10 Jeremy J. Drake , Klaus Werner

We present results of a global survey of single-pixel intensity power spectra from a 12-hour time period on 26 June 2013 in a 1600x1600 pixel region from four channels of the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly…

Solar and Stellar Astrophysics · Physics 2019-01-29 Karl Battams , Brendan M. Gallagher , Robert S. Weigel