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In coronal loop modeling, it is commonly assumed that the loops are semi-circular with a uniform cross-sectional area. However, observed loops are rarely semi-circular, and extrapolations of the magnetic field show that the field strength…
Coronal loops in active regions are the subjects of intensive investigation, but the important diffuse 'unresolved' emission in which they are embedded has received relatively little attention. Here we measure the densities and emission…
The perplexing mystery of what maintains the solar coronal temperature at about a million K, while the visible disc of the Sun is only at 5800 K, has been a long standing problem in solar physics. A recent study by Mondal(2020) has provided…
Decaying active region 10942 is investigated from 4:00-16:00 UT on February 24, 2007 using a suite of EUV observing instruments. Results from Hinode/EIS, STEREO and TRACE show that although the active region has decayed and no sunspot is…
The heating of coronal loops is investigated to understand the observational consequences in terms of the thermodynamics and radiative losses from the Sun as well as the magnetized coronae of stars with an outer convective envelope. The…
Post-flare arcades are well-known components of solar flare evolution, which have been observed for several decades. Coronal rain, cascades of catastrophically-cooled plasma, outline the loops and provide eye-catching evidence of the recent…
The energy input into the lower solar corona by flare evaporation events has been modeled according to the available observations for quiet regions. The question is addressed whether such heating events can provide the observed average…
Solar corona is much hotter than lower layers of the solar atmosphere-photosphere and chromosphere. The coronal temperature is up to 1MK in quiet sun areas, while up to several MK in active regions, which implies a key role of magnetic…
It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona low-FIP elements, such as Fe, Si,…
On 13 February 2009, a coronal wave -- CME -- dimming event was observed in quadrature by the STEREO spacecraft. We analyze this event using a three-dimensional, global magnetohydrodynamic (MHD) model for the solar corona. The numerical…
How the solar atmosphere is heated from a temperature of about $5,000-6,000$\,K in the lower atmosphere to about $1-2$\,MK in the corona has challenged the astrophysical community for about 80 years. The same puzzle exists for the stellar…
Understanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the…
It was once thought that all coronal loops are in static equilibrium, but observational and modeling developments over the past decade have shown that this is clearly not the case. It is now established that warm (~1 MK) loops observed in…
The effect of the numerical spatial resolution in models of the solar corona and corona / chromosphere interface is examined for impulsive heating over a range of magnitudes using one dimensional hydrodynamic simulations. It is demonstrated…
The solar atmosphere shows anomalous variation in temperature, starting from the 5500 K photosphere to the million-degree Kelvin corona. The corona itself expands into the interstellar medium as the free streaming solar wind, which…
The solar corona consists of a million-degree Kelvin plasma. A complete understanding of this phenomenon demands the study of Quiet Sun (QS) regions. In this work, we study QS regions in the 171 {\AA}, 193 {\AA} and 211 {\AA} passbands of…
We study the evolution of a group of TRACE 195 A coronal loops overlying a reverse S-shaped filament on 2001 June 15. These loops were initially pushed upward with the filament ascending and kinking slowly, but as soon as the filament rose…
We study a coronal mass ejection (CME) associated with an X-class flare, whose initiation is clearly observed in low corona with high-cadence, high-resolution EUV images, providing us a rare opportunity to witness the early evolution of an…
Using a full spectral scan of an active region from the Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained Emission Measure EM$(T)$ distributions in two different moss regions within the same active region. We have compared…
The transition region between the Sun's corona and chromosphere is important to the mass and energy transfer from the lower atmosphere to the corona; consequently, this region has been studied intensely with ultraviolet (UV) and extreme…