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Coronal rain is the well-known phenomenon in which hot plasma high in the Sun's corona undergoes rapid cooling (from > 10^6 K to < 10^4 K), condenses, and falls to the surface. Coronal rain appears frequently in active region coronal loops…

太阳与恒星天体物理 · 物理学 2019-04-22 E. I. Mason , S. K. Antiochos , N. M. Viall

Previous observations have not been able to exclude the possibility that high temperature active region loops are actually composed of many small scale threads that are in various stages of heating and cooling and only appear to be in…

太阳与恒星天体物理 · 物理学 2014-11-20 Harry P. Warren , Amy R. Winebarger , David H. Brooks

Coronal holes (CH) emit significantly less at coronal temperatures than quiet-Sun regions (QS), but can hardly be distinguished in most chromospheric and lower transition region lines. A key quantity for the understanding of this phenomenon…

天体物理学 · 物理学 2009-06-25 T. Wiegelmann , S. K. Solanki

One of the most important features in the solar atmosphere is magnetic network and its rela- tionship with the transition region (TR), and coronal brightness. It is important to understand how energy is transported into the corona and how…

太阳与恒星天体物理 · 物理学 2018-03-21 Ehsan Tavabi

We perform multiwavelength time-distance analysis of a fan loop system anchored in an isolated sunspot region AR 12553. The active region was observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We measure…

太阳与恒星天体物理 · 物理学 2020-07-01 Aishawnnya Sharma , Durgesh Tripathi , Robertus Erdelyi , G. R. Gupta , G. A. Ahmed

Context: On 2020 May 30, small and short-lived EUV brightenings were observed in the Quiet Sun (QS) during a four minutes sequence by EUI/HRIEUV on board Solar Orbiter. Their physical origin and possible impact on coronal or Transition…

The coronal magnetic field above a particular photospheric region will vanish at a certain number of points, called null points. These points can be found directly in a potential field extrapolation or their density can be estimated from…

天体物理学 · 物理学 2009-11-13 D. W. Longcope , C. E. Parnell

A challenge in characterizing active region (AR) coronal heating is in separating transient (bursty) loop heating from the diffuse background (steady) heating. We present a method of quantifying coronal heating's bursty and steady…

太阳与恒星天体物理 · 物理学 2023-01-04 Sanjiv K. Tiwari , Lucy A. Wilkerson , Navdeep K. Panesar , Ronald L. Moore , Amy R. Winebarger

We present a comprehensive radiative magnetohydrodynamic simulation of the quiet Sun and large solar active regions. The 197 Mm wide simulation domain spans from 18 (10) Mm beneath the photosphere to 113 Mm in the solar corona. Radiative…

太阳与恒星天体物理 · 物理学 2022-10-12 Feng Chen , Matthias Rempel , Yuhong Fan

A joint campaign of several space-borne and ground-based observatories, such as the GREGOR solar telescope, the Extreme-ultraviolet Imaging Spectrometer (EIS), and the Interface Region Imaging Spectrograph (Hinode Observing Plan 381, 11-22…

Solar flare electron acceleration is an efficient process, but its properties (mechanism, location) are not well constrained. Via hard X-ray (HXR) emission, we routinely observe energetic electrons at the Sun, and sometimes we detect…

太阳与恒星天体物理 · 物理学 2023-10-09 Ross Pallister , Natasha L. S. Jeffrey

Solar observations with the Atacama Large Millimeter/submillimeter Array (ALMA) provide us with direct measurements of the brightness temperature in the solar chromosphere. We study the temperature distributions obtained with ALMA Band 6…

太阳与恒星天体物理 · 物理学 2019-02-13 Shahin Jafarzadeh , Sven Wedemeyer , Mikolaj Szydlarski , Bart De Pontieu , Reza Rezaei , Mats Carlsson

Plasma upflows with a Doppler shift exceeding -10 km/s at active region (AR) boundaries are considered potential sources of the nascent slow solar wind. We investigate the driving mechanisms of a pair of coronal upflow regions on the…

Most observations of the solar corona beyond 2 Rs consist of broadband visible light imagery from coronagraphs. The associated diagnostics mainly consist of kinematics and derivations of the electron number density. While the measurement of…

太阳与恒星天体物理 · 物理学 2023-06-28 Auchère , F. , Berghmans , D. , Dumesnil , C. , Halain , J. -P. , Mercier , R. , Rochus , P. , Delmotte , F. , François , S. , Hermans , A. , Hervier , V. , Kraaikamp , E. , Meltchakov , E. , Morinaud , G. , Philippon , A. , Smith , P. J. , Stegen , K. , Verbeeck , C. , Zhang , X. Y. , Andretta , V. , Abbo , L. , Buchlin , E. , Frassati , F. , Gissot , S. , Gyo , M. , Harra , L. , Jerse , G. , Landini , F. , Mierla , M. , Nicula , B. , Parenti , S. , Renotte , E. , Romoli , M. , Russano , G. , Sasso , C. , Schühle , U. , Schmutz , W. , Soubrié , E. , Susino , R. , Teriaca , L. , West , M. , Zhukov , A. N

How structures, e.g., magnetic loops, in the upper atmosphere, i.e., the transition region and corona, are heated and sustained is one of the major unresolved issues in solar and stellar physics. Various theoretical and observational…

太阳与恒星天体物理 · 物理学 2023-06-07 Leping Li , Hui Tian , Huadong Chen , Hongqiang Song , Zhenyong Hou , Xianyong Bai , Kaifan Ji , Yuanyong Deng

We report on the plasma properties of small-scale transient events identified in the quiet Sun, coronal holes and their boundaries. We use spectroscopic co-observations from SUMER/SoHO and EIS/Hinode combined with high cadence imaging data…

太阳与恒星天体物理 · 物理学 2015-06-05 M. S. Madjarska , Z. Huang , J. G. Doyle , S. Subramanian

Using detrended fluctuation analysis (DFA) and rescaled range (R/S) analysis, we investigate the scaling properties of EUV intensity fluctuations of low-latitude coronal holes (CHs) and neighboring quiet-Sun (QS) regions in signals obtained…

太阳与恒星天体物理 · 物理学 2020-01-08 Ana Cristina Cadavid , Mari Paz Miralles , Kristine Romich

Extreme UV (EUV) and X-ray loops in the solar corona connect regions of enhanced magnetic activity, but they are not usually rooted in the dark umbrae of sunspots because the strong magnetic field found there suppresses convection. This…

太阳与恒星天体物理 · 物理学 2016-02-17 L. P. Chitta , H. Peter , P. R. Young

We present an initial study of one of the first ALMA Band 3 observations of the Sun with the aim to characterise the diagnostic potential of brightness temperatures measured with ALMA on the Sun. The observation covers 48min at a cadence of…

Magnetic flux rope is believed to be an important structural component of coronal mass ejections (CMEs). While there exist much observational evidence of the flux rope after the eruption, e.g., as seen in remote-sensing coronagraph images…

太阳与恒星天体物理 · 物理学 2015-05-27 X. Cheng , J. Zhang , Y. Liu , M. D. Ding