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I discuss the X-ray observations of Be stars, and how their properties compare to non-emission B stars. I focus on several specific stars that show high flux levels and variability but also report on several interesting survey results. The…

Astrophysics · Physics 2007-05-23 David H. Cohen

Strongly magnetized, accreting neutron stars show periodic and aperiodic variability over a wide range of time scales. By obtaining spectral and timing information on these different time scales, we can have a closer look into the physics…

High Energy Astrophysical Phenomena · Physics 2019-05-15 F. Fuerst , P. Kretschmar , V. Grinberg , K. Pottschmidt , J. Wilms , M. Kuehnel , I. El Mellah , S. Martinez-Nunez

The progress over the last years in modelling the atmospheres and winds of PN central stars is reviewed. We discuss the effect of the inclusion of the blanketing by millions of metal lines in NLTE on the diagnostics of photospheric and…

Astrophysics · Physics 2009-11-11 R. P. Kudritzki , M. A. Urbaneja , J. Puls

Studies of element abundances in stars are of fundamental interest for their impact in a wide astrophysical context, from our understanding of galactic chemistry and its evolution, to their effect on models of stellar interiors, to the…

Solar and Stellar Astrophysics · Physics 2015-05-20 Paola Testa

The past two decades have witnessed the rapid growth of our knowledge of the X-ray Universe thanks to flagship X-ray space observatories like XMM-Newton and Chandra. A significant portion of discoveries would have been impossible without…

High Energy Astrophysical Phenomena · Physics 2023-07-06 Junjie Mao , Frits Paerels , Matteo Guainazzi , Jelle S. Kaastra

Microquasars are accreting X-ray binary systems with non-thermal radio jets. In some of these systems the jet is expected to be strongly misaligned with the perpendicular to the orbital plane. If the donor star is an early-type star, the…

Astrophysics · Physics 2009-11-11 Gustavo E. Romero , Mariana Orellana

Analysis of observations with XMM-Newton have made a significant contribution to the study of Gamma-ray Burst (GRB) X-ray afterglows. The effective area, bandpass and resolution of the EPIC instrument permit the study of a wide variety of…

Astrophysics · Physics 2007-05-23 P. T. O'Brien , J. N. Reeves , D. Watson , J. Osborne , R. Willingale

There exists a significant population of broad line, z~2 QSOs which have heavily absorbed X-ray spectra. Follow up observations in the submillimetre show that these QSOs are embedded in ultraluminous starburst galaxies, unlike most…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 M. J. Page , F. J. Carrera , J. A. Stevens , J. Ebrero , A. J. Blustin

Two sources of X-ray emission are expected from planetary nebulae: the hot central stars with $T_{eff} > 10^5$ K, and shocked fast stellar winds at temperatures of 10$^6 - 10^7$ K. The stellar emission and nebular emission differ in spatial…

Astrophysics · Physics 2007-05-23 You-Hua Chu , Martin A. Guerrero , Robert A. Gruendl

Wind-blown bubbles, from those around massive O and Wolf-Rayet stars, to superbubbles around OB associations and galactic winds in starburst galaxies, have a dominant role in determining the structure of the Interstellar Medium. X-ray…

Astrophysics · Physics 2009-10-30 David K. Strickland , Ian R. Stevens

With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like…

We investigate the possibility of obscuring supersoft X-ray sources in the winds of companion stars. We derive limits on the amount of circumstellar material needed to fully obscure a 'canonical' supersoft X-ray source in the Large…

High Energy Astrophysical Phenomena · Physics 2011-09-28 Mikkel Thomas Bøje Nielsen , Carsten Dominik , Gijs Nelemans

Because of its complex clumpy wind, prominent cyclotron resonant scattering features, intrinsic variability and convenient physical parameters (close distance, high inclination, small orbital separation) which facilitate the observation and…

High Energy Astrophysical Phenomena · Physics 2022-04-20 C. M. Diez , V. Grinberg , F. Fürst , E. Sokolova-Lapa , A. Santangelo , J. Wilms , K. Pottschmidt , S. Martínez-Núñez , C. Malacaria , P. Kretschmar

Recent advances in the modelling of stellar winds driven by radiation pressure make it possible to fit many wind-sensitive features in the UV spectra of hot stars, opening the way for a hydrodynamically consistent determination of stellar…

Astrophysics · Physics 2007-05-23 A. W. A. Pauldrach , T. L. Hoffmann , R. H. Méndez

We review some of the ways that X-ray observations provide unique information on radio galaxies. Thermal bremsstrahlung X-ray emission provides detailed data on ambient densities and temperatures. These parameters in turn can be used for…

Astrophysics · Physics 2007-05-23 D. E. Harris

Extended X-ray emission can be studied either spatially (through its surface brightness profile) or spectrally (by analyzing the spectrum at various locations in the field). Both techniques have advantages and disadvantages, and when the…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Michael E. Anderson , Joel N. Bregman

Based on time-dependent radiation-hydrodynamics simulations of the evolution of Planetary Nebulae (PNe), we have carried out a systematic parameter study to address the non-trivial question of how the diffuse X-ray emission of PNe with…

Solar and Stellar Astrophysics · Physics 2015-05-30 M. Steffen , C. Sandin , R. Jacob , D. Schoenberner

Ultraluminous X-ray sources are non-nuclear point sources exceeding the Eddington luminosity of a 10 Solar mass black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or…

High Energy Astrophysical Phenomena · Physics 2017-12-20 P. Kosec , C. Pinto , A. C. Fabian , D. J. Walton

The Standard Model of particle physics can be extended to include sterile (right-handed) neutrinos or axions to solve the dark matter problem. Depending upon the mixing angle between active and sterile neutrinos, the latter have the…

High Energy Astrophysical Phenomena · Physics 2017-06-28 A. Gewering-Peine , D. Horns , J. H. M. M. Schmitt

This paper summarizes recents results in gamma-ray astronomy, most of which were derived with data from ground-based gamma-ray detectors. Many of the contributions presented at this conference involve multiwavelength studies which combine…

Astrophysics · Physics 2007-05-23 Martin Pohl
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