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Polarizability tensor of a strongly magnetized plasma and the polarization vectors and opacities of normal electromagnetic waves are studied for the conditions typical of neutron star atmospheres, taking account of partial ionization…

Astrophysics · Physics 2009-11-10 A. Y. Potekhin , Dong Lai , G. Chabrier , W. C. G. Ho

The X-ray spectra of late type stars can generally be well fitted by a two temperature component model of the corona. We fnd that the temperature of both components are strong functions of stellar age, although the temperature of the hotter…

Astrophysics · Physics 2017-01-18 Hwankyung Sung , M. S. Bessell , Hugues Sana

Solar images taken simultaneously at different wavelengths in the EUV are widely used for understanding structures such as flares, coronal holes, loops, etc. The line-of-sight integration and the finite spectral resolution of EUV…

Astrophysics · Physics 2009-11-13 T. Dudok de Wit , F. Auchere

Comets are pristine remnants of the Solar system, composed of dust and ice. They remain inactive and undetectable for most of their orbit due to low temperatures. However, as they approach the Sun, volatile materials sublimate, expelling…

Earth and Planetary Astrophysics · Physics 2023-11-20 K. Aravind , Shashikiran Ganesh

Several laboratory facilities were used to benchmark theoretical spectral models those extensively used by astronomical communities. However there are still many differences between astrophysical environments and laboratory miniatures that…

Solar and Stellar Astrophysics · Physics 2014-03-05 G. Y. Liang , F. Li , F. L. Wang , Y. Wu , J. Y. Zhong , G. Zhao

Polarimetry in the far-infrared and submillimeter has been valuable in tracing magnetic fields in bright Galactic Clouds. We discuss the techniques we have developed and trends we have found in polarization vs column density, and vs…

Astrophysics · Physics 2015-06-24 Roger Hildebrand

The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal…

Solar and Stellar Astrophysics · Physics 2017-10-11 Steven R. Cranmer , Sarah E. Gibson , Pete Riley

In recent years, the development of spectropolarimetric techniques deeply modified our knowledge of stellar magnetism. In the case of solar-type stars, the challenge is to measure a geometrically complex field and determine its evolution…

Astrophysics · Physics 2007-05-23 P. Petit

The dynamical response of the solar corona to surface and sub-surface perturbations depends on the chromospheric stratification, and specifically on how efficiently these layers reflect or transmit incoming Alfv\'en waves. While it would be…

Solar and Stellar Astrophysics · Physics 2015-06-12 R. F. Pinto , R. Grappin , M. Velli , A. Verdini

Polarimetric observations of the twilight sky are effective for the investigations of scattering properties of the atmosphere at different altitudes. Modern computer technique allows to reduce the influence of multiple scattering on the…

Atmospheric and Oceanic Physics · Physics 2007-05-23 O. V. Postylyakov , O. S. Ugolnikov , I. A. Maslov , A. N. Masleev

Major solar flares are prone to occur in active region atmospheres associated with large, complex, dynamically-evolving sunspots. This points to the importance of monitoring the evolution of starspots, not only in visible but also in ultra…

Solar and Stellar Astrophysics · Physics 2020-10-14 Shin Toriumi , Vladimir S. Airapetian , Hugh S. Hudson , Carolus J. Schrijver , Mark C. M. Cheung , Marc L. DeRosa

We present some recent highlights and prospects for the study of hot astrophysical plasmas. Hot plasmas can be studied primarily through their X-ray emission and absorption. Most astrophysical objects, from solar system objects to the…

High Energy Astrophysical Phenomena · Physics 2017-09-13 J. S. Kaastra , L. Gu , J. Mao , M. Mehdipour , F. Mernier , J. de Plaa , A. J. J. Raassen , I. Urdampilleta

How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the…

A significant impediment to solving the coronal heating problem is that we currently only observe active region (AR) loops in their cooling phase. Previous studies showed that the evolution of cooling loop densities and apex temperatures…

Solar and Stellar Astrophysics · Physics 2024-01-10 David H. Brooks , Jeffrey W. Reep , Ignacio Ugarte-Urra , John E. Unverferth , Harry P. Warren

The Very Local Interstellar Medium (VLISM) contains clouds which consist of partially-ionized plasma. These clouds can be effectively diagnosed via high resolution optical and ultraviolet spectroscopy of the absorption lines they form in…

Astrophysics of Galaxies · Physics 2015-05-19 Steven R. Spangler , Allison H. Savage , Seth Redfield

Suprathermal ions in the corona are thought to serve as seed particles for large gradual solar energetic particle (SEP) events associated with fast and wide coronal mass ejections (CMEs). A better understanding of the role of suprathermal…

Solar and Stellar Astrophysics · Physics 2022-02-02 Bin Zhuang , Noé Lugaz , David Lario

Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which…

The topic of wind-clumping has been the subject of much activity in recent years, due to the impact that it can have on derived mass-loss rates. Here we present an alternative method of investigating wind-clumping, that of polarimetry. We…

Astrophysics · Physics 2007-05-23 Ben Davies , Jorick S. Vink , Rene D. Oudmaijer

In this review we summarize results of our analysis of the observations of solar eruptive flares made by the Ond\v{r}ejov radiospectrograph for more than twenty years. We also present some Potsdam-Tremsdorf radio spectra from our common…

Solar and Stellar Astrophysics · Physics 2023-07-17 Marian Karlický

A forefront area of research concerns the exploration of the properties of hadronic matter under extreme conditions of temperature and density, and the determination of the equation of state--the relation between pressure, temperature and…

Astrophysics · Physics 2008-11-26 F. Weber , R. Negreiros , P. Rosenfield , M. Stejner