Related papers: Universal Scaling Laws for Solar and Stellar Atmos…
The formation of extremely hot outer atmospheres is one of the most prominent manifestations of magnetic activity common to the late-type dwarf stars, including the Sun. It is widely believed that these atmospheric layers, the corona,…
Determining the heating mechanism (or mechanisms) that causes the outer atmosphere of the Sun, and many other stars, to reach temperatures orders of magnitude higher than their surface temperatures has long been a key problem. For decades…
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…
Observations show that the coronal X-ray emission of the Sun and other stars depends on the surface magnetic field. Using power-law scaling relations between different physical parameters, we build an analytical model to connect the…
What physical mechanisms heat the outer solar or stellar atmosphere to million-Kelvin temperatures is a fundamental but long-standing open question. In particular, the solar corona in active region cores contains an even hotter component…
It remains unclear which physical processes are responsible for the dramatic increase with height of the temperature in stellar atmospheres, known as the chromospheric ($\sim$10,000 K) and coronal (several million K) heating problems.…
The solar atmosphere is dominated by loops of magnetic flux which connect the multi-million-degree corona to the much cooler chromosphere. The temperature and density structure of quasi-static loops is determined by the continuous flow of…
Stellar coronae are believed to be the main birthplace of various stellar magnetic activities. However, the structures and properties of stellar coronae remain poorly understood. Using the Space Weather Modelling Framework with the…
The X-ray and extreme-ultraviolet (EUV) emissions from the low-mass stars significantly affect the evolution of the planetary atmosphere. However, it is, observationally difficult to constrain the stellar high-energy emission because of the…
The corona is a structure possessed by stars, including the sun. The abnormal heating of the solar corona and chromosphere is one of the greatest mysteries in modern astronomy. While state-of-the-art observations have identified some…
The emission of the upper atmosphere of the Sun is closely related to magnetic field concentrations at the solar surface. It is well established that this relation between chromospheric emission and magnetic field is nonlinear. Here we…
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…
The Sun's corona is millions of degrees hotter than its 5,000 K photosphere. This heating enigma is typically addressed by invoking the deposition at coronal heights of non-thermal energy generated by the interplay between convection and…
Observations of the coronae of the Sun and of solar-like stars provide complementary information to advance our understanding of stellar magnetic activity, and of the processes leading to the heating of their outer atmospheres. While solar…
Extreme-ultraviolet and X-ray emissions from stellar coronae drive mass loss from exoplanet atmospheres, and ultraviolet emission from stellar chromospheres drives photo-chemistry in exoplanet atmospheres. Comparisons of the spectral energy…
We model a coronal loop as a three-dimensional magnetic cylinder in a realistic solar atmosphere that extends from the chromosphere to the corona. Kink oscillations, believed ubiquitous in the solar corona, are launched in the loop. Heating…
The question why the solar corona is much hotter than the visible solar surface still puzzles solar researchers. Most theories of the coronal heating involve a tight coupling between the coronal magnetic field and the associated thermal…
The coronal heating problem remains one of the most challenging questions in solar physics. The energy driving coronal heating is widely understood to be associated with convective motions below the photosphere. Recent high-resolution…
The outer solar atmosphere, the corona, contains plasma at temperatures of more than a million K, more than 100 times hotter that solar surface. How this gas is heated is a fundamental question tightly interwoven with the structure of the…
All but the most massive main-sequence stars are expected to have a rarefied and hot (million-Kelvin) corona like the Sun. How such a hot corona is formed and supported has not been completely understood yet, even in the case of the Sun.…