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The heating of the solar corona is one of the big questions in astrophysics. Rapid pulses called nanoflares are among the best candidate mechanisms. The analysis of the time variability of coronal X-ray emission is potentially a very useful…

Solar and Stellar Astrophysics · Physics 2012-01-27 S. Terzo , F. Reale , M. Miceli , R. Kano , S. Tsuneta , J. A. Klimchuk

We perform an analysis of the line-of-sight (LOS) observables of the SDO/HMI for models of the solar atmosphere heated by precipitating high-energy electrons during solar flares. The radiative hydrodynamic (RADYN) flare models are obtained…

Solar and Stellar Astrophysics · Physics 2020-04-15 Viacheslav M Sadykov , Alexander G Kosovichev , Irina N Kitiashvili , Graham S Kerr

High resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of…

Solar and Stellar Astrophysics · Physics 2023-11-01 Paola Testa , Helle Bakke , Luc Rouppe van der Voort , Bart De Pontieu

While the {\it Helioseismic and Magnetic Imager} (HMI) onboard the {\it Solar Dynamics Observatory} (SDO) provides Doppler velocity [$V$], continuum intensity [$I_C$], and line-depth [$Ld$] observations, each of which is sensitive to the…

Solar and Stellar Astrophysics · Physics 2015-09-24 Rachel Howe , Kiran Jain , Richard S. Bogart , Deborah A. Haber , Charles S. Baldner

Context. Emission lines formed in the transition region and corona show dominantly redshifts and blueshifts, respectively. Aims. We investigate the Doppler shifts in a 3D radiation MHD model of the quiet Sun and compare these to observed…

Solar and Stellar Astrophysics · Physics 2022-05-11 Yajie Chen , Hardi Peter , Damien Przybylski , Hui Tian , Jiale Zhang

We study plasma flows along selected coronal loops in NOAA Active Region 10926, observed on 3 December 2006 with Hinode's EUV Imaging Spectrograph (EIS). From the shape of the loops traced on intensity images and the Doppler shifts measured…

Solar and Stellar Astrophysics · Physics 2015-06-05 P. Syntelis , C. Gontikakis , M. K. Georgoulis , C. E. Alissandrakis , K. Tsinganos

A well known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the…

Solar and Stellar Astrophysics · Physics 2015-06-04 Nicholeen M. Viall , James A. Klimchuk , NASA Goddard Space Flight Center

We present ac susceptibility and specific heat measurements taken on samples of LiHo$_x$Y$_{1-x}$F$_4$ in the dilute limit: x = 0.018, 0.045, 0.080 and 0.12. Susceptibility measurements show glassy behavior including wide absorption spectra…

Disordered Systems and Neural Networks · Physics 2015-06-05 J. A. Quilliam , S. Meng , J. B. Kycia

Measuring the temperature and abundance patterns of clouds in the interstellar medium (ISM) provides an observational basis for models of the physical conditions within the clouds, which play an important role in studies of star and planet…

Astrophysics of Galaxies · Physics 2019-06-26 Nicholas Kruczek , Kevin France , Keri Hoadley , Brian Fleming , Nicholas Nell

Various bright structures abound in the chromosphere playing an essential role in the dynamics and evolution therein. Tentatively identifying the wave characteristics in the outer solar atmosphere helps to understand this layer better. One…

Solar and Stellar Astrophysics · Physics 2022-10-26 Rayhane Sadeghi , Ehsan Tavabi

The large uncertainties associated with measuring the amount of high temperature emission in solar active regions represents a significant impediment to making progress on the coronal heating problem. Most current observations at…

Solar and Stellar Astrophysics · Physics 2012-07-20 Luca Teriaca , Harry Warren , Werner Curdt

Effective electron mobilities are obtained by transport measurements on InAs nanowire field-effect transistors at temperatures ranging from 10-200 K. The mobility increases with temperature below ~ 30 - 50 K, and then decreases with…

Mesoscale and Nanoscale Physics · Physics 2013-05-27 Nupur Gupta , Yipu Song , Gregory W. Holloway , Urbasi Sinha , Chris Haapamaki , Ray R. LaPierre , Jonathan Baugh

The radiance and Doppler-shift distributions across the solar network provide observational constraints of two-dimensional modeling of transition-region emission and flows in coronal funnels. Two different methods, dispersion plots and…

Solar and Stellar Astrophysics · Physics 2009-07-17 H. Tian , C. -Y. Tu , L. -D. Xia , J. -S. He

We report on observations of a solar prominence obtained on 26 April 2007 using the Extreme Ultraviolet Imaging Spectrometer on Hinode. Several regions within the prominence are identified for further analysis. Selected profiles for lines…

Solar and Stellar Astrophysics · Physics 2015-03-13 Nicolas Labrosse , Brigitte Schmieder , Petr Heinzel , Tetsuya Watanabe

We use spectropolarimetric observations of the Ca II 8542~\AA\ line, taken from the Swedish 1-m Solar Telescope (SST), in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show…

Solar and Stellar Astrophysics · Physics 2017-08-30 A. Reid , V. Henriques , M. Mathioudakis , J. G. Doyle , T. Ray

By using a new method of forced-field extrapolation, we study the emerging flux region AR 11850 observed by the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamical Observatory (SDO). Our results suggest that the bright points…

Solar and Stellar Astrophysics · Physics 2017-02-15 Jie Zhao , Brigitte Schmieder , Hui Li , Etienne Pariat , Xiaoshuai Zhu , Li Feng , Michalina Grubecka

The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) and the Hinode/ EUV Imaging Spectrometer (EIS) observed AR 11726 on 2013 April 23. We present intensity images in numerous atomic lines constructed from these observations. These…

Solar and Stellar Astrophysics · Physics 2018-07-03 Joel Allred , Adrian Daw , Jeffrey Brosius

This paper investigates a quiescent (non-flaring) active region observed on July 13, 2010 in EUV, SXR, and HXRs to search for a hot component that is speculated to be a key signature of coronal heating. We use a combination of RHESSI…

Solar and Stellar Astrophysics · Physics 2019-05-15 Shin-nosuke Ishikawa , Sam Krucker

Magnetic twist of the active region has been measured over a decade using photospheric vector field data, chromospheric H_alpha data, and coronal loop data. The twist and tilt of the active regions have been measured at the photospheric…

Solar and Stellar Astrophysics · Physics 2017-08-02 B. Ravindra , P. Venkatakrishnan , Sanjiv Kumar Tiwari

Measuring coverage of dark spots on cool stars is important in understanding how stellar magnetic activity scales with the rotation rate and convection zone depth. In this respect, it is crucial to infer surface magnetic patterns on G and K…

Solar and Stellar Astrophysics · Physics 2023-10-24 Engin Bahar , Hakan V. Şenavcı , Emre Işık , Gaitee A. J. Hussain , Oleg Kochukhov , David Montes , Yue Xiang