X-ray emission from the winds of hot stars

Lucy, L. B.; White, R. L.

doi:10.1086/158342

Cited by 418 publications

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“…Linear stability analyses already proved in the early 80s (Lucy and White, 1980) that line-driven winds are unstable for velocity perturbations. During the non-linear growth of the instability, high-speed material steepens into strong reverse shocks that compress most of the wind mass into finite dense "clumps" and leave the surroundings filled-up with a lower density medium (Owocki et al, 1988).…”

Section: Take the Rough With The Smoothmentioning

confidence: 99%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

234

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High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

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Section: Take the Rough With The Smoothmentioning

confidence: 99%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

234

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“…The investigations were continued with ASCA (Corcoran et al 1994) and ROSAT (Haberl & White 1993;Berghöfer et al 1996). Although the origin of the emission was initially a matter of debate, it is now generally believed that instabilities and clumping in the strong line-driven stellar wind is the mechanism that heats small parts of the wind (e.g., Lucy & Solomon 1970;Lucy & White 1980;Lucy 1982;Owocki et al 1988;Dessart & Owocki 2005). The launches of Chandra and XMM-Newton in 1999 with high-resolution instruments aboard have offered the possibility to study the X-ray spectra in more detail, resulting in, e.g., estimates of line ratios, line profiles, temperatures, emission measures, and abundances (Waldron & Cassinelli 2001Cohen et al 2006;Kahn et al 2001;Raassen et al 2008).…”

Section: Introductionmentioning

confidence: 99%

The X-ray spectrum ofδOrionis observed by LETGS aboardChandra

Raassen

Pollock

2013

A&A

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Aims. We analyze the high-resolution X-ray spectrum of the supergiant O-star δ Orionis (O9.5II) with line ratios of He-like ions and a thermal plasma model, and we examine its variability. Methods. The O-supergiant δ Ori was observed in the wavelength range 5-175 Å by the X-ray detector HRC-S in combination with the grating LETG aboard Chandra. We studied the He-like ions in combination with the UV-radiation field to determine local plasma temperatures and to establish the distance of the X-ray emitting ions to the stellar surface. We measured individual lines by means of Gaussian profiles, folded through the response matrix, to obtain wavelengths, line fluxes, half widths at half maximum (HWHM) and line shifts to characterize the plasma. We consider multitemperature models in collisional ionization equilibrium (CIE) to determine temperatures, emission measures, and abundances.Results. Analysis of the He-like triplets extended to N vi and C v implies ionization stratification with the hottest plasma to be found within a few stellar radii 3 R * (Mg xi) and the coolest farther out, far beyond the acceleration zone, up to 49 R * (N vi) and 75 R * (C v).The observed temperatures cover a range from about 0.1 to 0.7 keV, i.e., 1-8 MK. The X-ray luminosity (L x ) is ∼1.5 × 10 32 erg/s in the range from 0.07 to 3 keV covered by LETGS. Velocity widths of about 1040 km s −1 have been determined.

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“…With respect to the soft X-ray emission of O stars (detected by Seward et al 1979 andHarnden et al 1979), Cassinelli and Olson (1979) on the ionization structure. Finally, Lucy and White (1980) and Owocki, Castor, and Rybicki (1988) have distinguished themselves with basic theoretical investigations of time-dependent radiation hydrodynamics which describe the creation and development of shocks (for more details about the role of X-rays in the atmospheres of Hot Stars see the reviews of Pauldrach et al 1994b andKudritzki andPuls 2000).…”

Section: Concept For Consistent Models Of Hot Star Atmospheresmentioning

confidence: 99%

Hot Stars: Old-Fashioned or Trendy?

Pauldrach¹

Reviews in Modern Astronomy 16

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X-ray emission from the winds of hot stars

Cited by 418 publications

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High-mass X-ray binaries in the Milky Way

High-mass X-ray binaries in the Milky Way

The X-ray spectrum ofδOrionis observed by LETGS aboardChandra

Hot Stars: Old-Fashioned or Trendy?

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