Radiation-driven winds of hot luminous stars

Pauldrach, A. W. A.; Hoffmann, T. L.; Méndez, R. H.

doi:10.1051/0004-6361:20034040

Cited by 75 publications

(219 citation statements)

References 18 publications

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“…Thus, we conclude that a more consistent treatment of expanding atmospheres was still needed for a detailed analysis. This more consistent treatment of expanding atmospheres that has now been applied and fixes the status quo is based on the improvements discussed in Section 6.1 (for a more comprehensive discussion see Pauldrach et al 2001 andPauldrach andHoffmann 2003). As is shown in Figure 19, the calculated synthetic spectrum is quite well in agreement with the spectra observed by IUE and Copernicus.…”

Section: Uv Analysis Of the Hot O Supergiant ζ Puppismentioning

confidence: 61%

“…Together with a revised inclusion of EUV and X-ray radiation produced by cooling zones which originate from the simulation of shock heated matter, these improvements have been implemented and described in a recent paper (Pauldrach et al 2001). Very recently we have additionally focused on a remaining aspect regarding hydrodynamical calculations which are consistent with the radiation field obtained from the line-overlap computations, and we have incorporated this improvement into our procedure (see Pauldrach and Hoffmann 2003).…”

Section: The General Methodsmentioning

confidence: 99%

“…Figure 22 shows that the windmomentum-luminosity relation indeed exists for massive O stars, as they follow the linear relation predicted by the theory, in a first approximation and for fixed metallicities. With regard to the spread in wind momenta found by Kudritzki et al (1997) for the Central Stars of Planetary Nebulae (lower part of Figure 22), Pauldrach et al (2002Pauldrach et al ( , 2003 have given a solution which, however, is unlikely to be believed yet by the part of the community working on stellar evolution.…”

Section: Wind Properties Of Massive O Starsmentioning

confidence: 99%

“…(Pauldrach et al 2003). The small vertical bars indicate the ionization thresholds for all important ions; the ionization balance depends almost entirely on the ionizing flux, and this influence can be traced by the spectral lines in the observable part of the UV spectrum.…”

Section: An Answer To This Question Requires An Ultimate Test!mentioning

confidence: 99%

“…The parameters are adjusted and the process is repeated until a good fit to all features in the observed UV spectrum is obtained. For a compact description of this procedure see Pauldrach et al 2002). It turned out that the effective temperature can be determined to within a range of ±1000 K and the abundances to at least within a factor of 2.…”

Section: Uv Analysis Of the Cool O Supergiant α Cammentioning

confidence: 99%

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Hot Stars: Old-Fashioned or Trendy?

Pauldrach¹

Reviews in Modern Astronomy 16

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Section: Uv Analysis Of the Hot O Supergiant ζ Puppismentioning

confidence: 61%

Section: The General Methodsmentioning

confidence: 99%

Section: Wind Properties Of Massive O Starsmentioning

confidence: 99%

Section: An Answer To This Question Requires An Ultimate Test!mentioning

confidence: 99%

Section: Uv Analysis Of the Cool O Supergiant α Cammentioning

confidence: 99%

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Hot Stars: Old-Fashioned or Trendy?

Pauldrach¹

Reviews in Modern Astronomy 16

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A hydrodynamical study of multiple‐shell planetary nebulae

et al. 2014

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We present the result of a study on the expansion properties and internal kinematics of round/elliptical planetary nebulae of the Milky Way disk, the halo, and of the globular cluster M 15. The purpose of this study is to considerably enlarge the small sample of nebulae with precisely determined expansion properties (Schönberner et al. 2005b). To this aim, we selected a representative sample of objects with different evolutionary stages and metallicities and conducted highresolutionéchelle spectroscopy. In most cases we succeeded in detecting the weak signals from the outer nebular shell which are attached to the main line emission from the bright nebular rim. Next to the measurement of the motion of the rim gas by decomposition of the main line components into Gaussians, we were able to measure separately, for most objects for the first time, the gas velocity immediately behind the leading shock of the shell, i.e. the post-shock velocity. We more than doubled the number of objects for which the velocities of both rim and shell are known and confirm that the overall expansion of planetary nebulae is accelerating with time. There are, however, differences between the expansion behaviour of the shell and the rim: The post-shock velocity is starting at values as low as around 20 km s −1 for the youngest nebulae, just above the AGB wind velocity of ∼ 10-15 km s −1 , and is reaching values of about 40 km s −1 for the nebulae around hotter central stars. Contrarily, the rim matter is at first decelerated below the typical AGB-wind velocity and remains at about 5-10 km s −1 for a while until finally a typical flow velocity of up to 30 km s −1 is reached. This observed distinct velocity evolution of both rim and shell is explained by radiation-hydrodynamics simulations, at least qualitatively: It is due to the ever changing stellar radiation field and wind-wind interaction together with the varying density profile ahead of the leading shock during the progress of evolution. The wind-wind interaction works on the rim dynamics while the radiation field and upstream density gradient is responsible for the shell dynamics. Because of these time-dependent boundary conditions, a planetary nebula will never evolve into a simple self-similar expansion. Also the metal-poor objects behave as theory predicts: The post-shock velocities are higher and the rim flow velocities are equal or even lower compared to disk objects at similar evolutionary stage. The old nebula around low-luminosity central stars contained in our sample expand still fast and are dominated by reionisation. We detected, for the first time, in some objects an asymmetric expansion behaviour: The relative expansions between rim and shell appear to be different for the receding and approaching parts of the nebular envelope.

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Mass loss from hot massive stars

Puls

Vink

Najarro

2008

Astron Astrophys Rev

609

620

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Mass loss is a key process in the evolution of massive stars, and must be understood quantitatively to be successfully included in broader astrophysical applications. In this review, we discuss various aspects of radiation driven mass loss, both from the theoretical and the observational side. We focus on winds from OB-stars, with some excursions to the Luminous Blue Variables, Wolf- Rayet stars, A-supergiants and Central Stars of Planetary Nebulae. After reca- pitulating the 1-D, stationary standard model of line-driven wind, extensions accounting for rotation and magnetic fields are discussed. The relevance of the so-called bi-stability jump is outlined. We summarize diagnostical methods to infer wind properties from observations, and compare the results with theore- tical predictions, featuring the massloss-metallicity dependence. Subsequently, we concentrate on two urgent problems which challenge our present understanding of radiation driven winds: weak winds and wind- clumping. We discuss problems of measuring mass-loss rates from weak winds and the potential of NIR- spectroscopy. Wind-clumping has severe implications for the interpretation of observational diagnostics, as derived mass-loss rates can be overestimated by factors of 2 to 10 if clumping is ignored, and we describe ongoing attempts to allow for more uniform results. We point out that independent arguments from stellar evolution favor a moderate reduction of present- day mass-loss rates. We also consider larger scale wind structure, interpreted in terms of co-rotating interacting regions, and complete this review with a discussion of recent progress on the X-ray line emission from massive stars, highlighting as to how far the analysis of such X-ray line emission can give further clues regarding an adequate description of wind clumping. (Abridged abstract)Comment: Astronomy and Astrophysics Review (accepted

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Radiation-driven winds of hot luminous stars

Cited by 75 publications

References 18 publications

Hot Stars: Old-Fashioned or Trendy?

Hot Stars: Old-Fashioned or Trendy?

A hydrodynamical study of multiple‐shell planetary nebulae

Mass loss from hot massive stars

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