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Extreme ultraviolet imaging spectroscopic observations often show an increase in line width around the loop-top or above-loop-top (ALT) region of solar flares, suggestive of turbulence. In addition, recent spectroscopic observations found…

太阳与恒星天体物理 · 物理学 2023-02-08 Kengo Shibata , Shinsuke Takasao , Katharine K. Reeves

We have measured line widths in active region coronal loops in order to determine whether the non-thermal broadening is anisotropic with respect to the magnetic field direction. These non-thermal velocities are caused by unresolved fluid…

太阳与恒星天体物理 · 物理学 2023-08-09 Michael Hahn , Mahboubeh Asgari-Targhi , Daniel Wolf Savin

Recent imaging observations with the Interface Region Imaging Spectrograp (IRIS) have revealed prevalent intermittent jets with apparent speeds of 80--250 km~s$^{-1}$ from the network lanes in the solar transition region (TR). On the other…

太阳与恒星天体物理 · 物理学 2019-03-13 Yajie Chen , Hui Tian , Zhenghua Huang , Hardi Peter , Tanmoy Samanta

Due to their characteristic temperature and density, loop structures in active regions (ARs) can be seen bright in extreme ultraviolet (EUV) and soft X-ray images. The semiempirical determination of the three-dimensional (3D) distribution…

太阳与恒星天体物理 · 物理学 2020-12-16 F. A. Nuevo , C. Mac Cormack , M. López Fuentes , A. M. Vásquez , C. H. Mandrini

Fully relativistic calculations of radiative rates and electron impact excitation cross sections for Fe X are used to derive theoretical emission-line ratios involving transitions in the 174-366 A wavelength range. A comparison of these…

天体物理学 · 物理学 2009-11-13 F P Keenan , D B Jess , K M Aggarwal , R J Thomas , J W Brosius , J M Davila

The advent of x-ray free-electron lasers (XFELs) has enabled a range of new experimental investigations into the properties of matter driven to extreme conditions via intense x-ray-matter interactions. The femtosecond timescales of these…

Context: One of the most prominent processes suggested to heat the corona to well above 10^6 K builds on nanoflares, short bursts of energy dissipation. Aims: We compare observations to model predictions to test the validity of the…

太阳与恒星天体物理 · 物理学 2015-11-04 Leping Li , Hardi Peter , Feng Chen , Jun Zhang

Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models, as well as their description of…

太阳与恒星天体物理 · 物理学 2016-01-13 N. B. Orange , D. L. Chesny , H. M. Oluseyi , K. Hesterly , M. Patel , P. R. Champey

Supernova 1987A offers a unique opportunity to study an evolving supernova in unprecedented detail over several decades. The X-ray emission is dominated by interactions between the ejecta and the circumstellar medium, primarily the…

高能天体物理现象 · 物理学 2021-08-11 Dennis Alp , Josefin Larsson , Claes Fransson

Using one-arcsecond-slit scan observations from the Hinode/EUV Imaging Spectrometer (EIS) on 05 February 2007, we find the plasma outflows in the open and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler velocity…

太阳与恒星天体物理 · 物理学 2015-06-22 A. K. Srivastava , P. Konkol , K. Murawski , B. N. Dwivedi , A. Mohan

Recent fully relativistic calculations of radiative rates and electron impact excitation cross sections for Fe {\sc xiii} are used to generate emission-line ratios involving 3s$^{2}$3p$^{2}$--3s3p$^{3}$ and 3s$^{2}$3p$^{2}$--3s$^{2}$3p3d…

天体物理学 · 物理学 2008-11-26 F P Keenan , D B Jess , K M Aggarwal , R J Thomas , J W Brosius , J M Davila

Coronal active regions are studied using Hinode/EIS observations in the EUV line Fe XII {\lambda}195.12 by analyzing their line profiles from 2006 December to 2019 December. The period covers the last 2 yr of solar cycle 23 and solar cycle…

太阳与恒星天体物理 · 物理学 2022-05-24 Maya Prabhakar , K. P Raju

Flare loops form an integral part of eruptive events, being detected in the range of temperatures from X-rays down to cool chromospheric-like plasmas. While the hot loops are routinely observed by the Solar Dynamics Observatory's…

太阳与恒星天体物理 · 物理学 2020-01-08 Július Koza , David Kuridze , Petr Heinzel , Sonja Jejčič , Huw Morgan , Maciej Zapiór

Two types of active region feature prominent at transition region temperatures are identified in Hinode/EIS data of AR 10938 taken on 2007 January 20. The footpoints of 1 MK TRACE loops are shown to emit strongly in emission lines formed at…

天体物理学 · 物理学 2015-05-13 P. R. Young , G. Del Zanna , H. E. Mason , G. A. Doschek , J. L. Culhane , H. Hara

We report on the structure and evolution of a current sheet that formed in the wake of an eruptive X8.3 flare observed at the west limb of the Sun on September 10, 2017. Using observations from the EUV Imaging Spectrometer (EIS) on Hinode…

太阳与恒星天体物理 · 物理学 2018-02-28 Harry P. Warren , David H. Brooks , Ignacio Ugarte-Urra , Jeffrey W. Reep , Nicholas A. Crump , George A. Doschek

We investigate intensity variations and energy deposition in five coronal loops in active region cores. These were selected for their strong variability in the AIA/SDO 94 {\AA} intensity channel. We isolate the hot Fe XVIII and Fe XXI…

太阳与恒星天体物理 · 物理学 2015-06-19 A. C. Cadavid , J. K. Lawrence , D. J. Christian , D. B. Jess , G. Nigro

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…

太阳与恒星天体物理 · 物理学 2012-07-20 Luca Teriaca , Harry Warren , Werner Curdt

Magnetic reconnection is the key mechanism for energy release in solar eruptions, where the high-temperature emission is the primary diagnostic for investigating the plasma properties during the reconnection process. Non-thermal broadening…

太阳与恒星天体物理 · 物理学 2022-11-15 Chengcai Shen , Vanessa Polito , Katharine K. Reeves , Bin Chen , Sijie Yu , Xiaoyan Xie

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…

太阳与恒星天体物理 · 物理学 2015-05-18 John T. Mariska , K. Muglach

Theoretical emission-line ratios involving Fe XI transitions in the 257-407 A wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross sections. These are subsequently…

太阳与恒星天体物理 · 物理学 2015-05-18 F. P. Keenan , R. O. Milligan , D. B. Jess , K. M. Aggarwal , M. Mathioudakis , R. J. Thomas , J. W. Brosius , J. M. Davila