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Saturday, July 25, 2020 | History

2 edition of Radiation driven winds of hot stars found in the catalog.

Radiation driven winds of hot stars

Radiation driven winds of hot stars

some remarks on stationary models and spectrum synthesis in time-dependent simulations

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  • 23 Currently reading

Published by Max-Planck-Institut für Astrophysik, National Aeronautics and Space Administration, National Technical Information Service, distributor in München, [Washington, DC, Springfield, Va .
Written in English

    Subjects:
  • Stellar winds.

  • Edition Notes

    StatementJoachim Puls ... [et al.].
    SeriesNASA contractor report -- NASA CR-194692.
    ContributionsPuls, Joachim., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL17680770M

    a more distant star. However, many stars have winds that are dense enough to be opaque at certain wavelengths of the star’s radiation, and this makes it possible to study them remotely through careful interpretation of the observed stellar spectra. The winds from massive, hot stars—with surface temperatures above about K—. Such winds exist on the sun and are responsible for phenomena like the northern lights. Cassinelli discovered that the winds associated with the star appear to be generated by the extremely short-wave ultraviolet radiation from the star pushing on atoms of stellar gas. "All early type stars seem to have radiation driven winds.

    Two studies were carried out to determine the effects of rotation on the winds from hot stars. The first study applies a rotating, magnetic, radiation-driven wind model to Be and Wolf-Rayet stars. The mass-loss rates in the equatorial region increase with rotation rate and an open magnetic field. In this way, a line-driven stellar wind bootstraps its own acceleration. Hot star winds, unlike the solar wind, have plenty of line opacity in the ultraviolet where most of the photospheric radiation is. This good matching between the radiation and the opacity allows for the efficient driving of winds in hot stars by radiation pressure.

    Title: Radiation driven instabilities in stellar winds: Creator: Carlberg, Raymond G. Date Issued: Description: This thesis investigates the quantitative nature of the variability which is present in the stellar winds of high luminosity early type stars. Winds in hot luminous stars are driven by radiation pressure. The stellar winds emerging from OB supergiants have numerous resonance lines in the UV, which coincidentally is where the continuum radiation of an OB star has its maximum. The winds from OB stars are thus referred to as line-driven winds, since the opacity of the accelerated.


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Radiation driven winds of hot stars Download PDF EPUB FB2

Wind models of very massive stars with metallicities in a range from 10 -4 to solar are calculated using a new treatment of radiation-driven winds with depth-dependent radiative force multipliers and a comprehensive list of more than two million spectral lines in non-LTE (NLTE). The models Radiation driven winds of hot stars book tested by a comparison with observed stellar wind properties of O stars in the Galaxy and Cited by: The winds from hot stars are driven by radiation.

The momentum of photospheric photons is absorbed by thousands of spectral lines and, thus, transfered to the atmospheric plasma. This physical process initiates and maintains stellar winds.

The physical modelling of winds requires the tools of non-LTE radiative transfer combined with hydrodynamics. Winds from hot stars (here a numerical simulation of the density distribution of a rapidly rotating wind) are driven by radiative line acceleration in thousands of metal lines close to flux maximum.

Since the winds are driven by radiative acceleration in metal lines, the stellar metal abundance affects not only the strenght, but also the structure of the spectral lines. Radiation-driven winds of hot stars.

VIII-The bistable wind of the luminous blue variable P Cygni (B1 Ia/+/) Article (PDF Available) in Astronomy and Astrophysics September Radiation-driven winds of hot luminous stars XVII. Parameters of selected central stars of PN from consistent optical and UV spectral analysis and the universality of the mass–luminosity relation nski, ach, and ffmann.

Butler, K.:Astronomical Society of the Pacific Conference Series Vol. 7, “Properties of Hot Luminous Stars”, ed. C.D. Garmany, p. Google Scholar.

Analytical solutions for radiation-driven winds of hot stars including the important finite cone angle effect (see Pauldrach et al., ; Friend and Abbott, ) are derived which approximate the detailed numerical solutions of the exact wind equation of motion very well.

They allow a detailed discussion of the finite cone angle effect and provide for given line force parameters k, alpha. Radiation driven winds of hot luminous stars XIV. Line statistics and radiative driving J. Puls, U. Springmann, and M. Lennon Universit¨ats-Sternwarte M¨unchen, Scheinerstr.

1, D M¨unchen, Germany Received March 18; accepted Septem Abstract. This. Pauldrach A., Kudritzki R.P., Gabler R., Wagner A. () Radiation Driven Winds of Central Stars of Planetary Nebulae. In: Bianchi L., Gilmozzi R. (eds) Mass Outflows from Stars and Galactic Nuclei. Astrophysics and Space Science Library (A Series of Books on the Recent Developments of Space Science and of General Geophysics and Astrophysics.

WINDS FROM HOT STARS adapted from R.-P. Kudritzki and J. Puls, Annual Review of Astronomy and Astrophysics () 1 Introduction. All hot stars have winds driven by radiation.

These winds become directly observable in spectral energy distributions and spectral lines as soon as the stars are above certain luminosity borderlines in the HRD. Radiation-driven winds of hot luminous stars XV. Constraints on the mass–luminosity relation of central stars of planetary nebulae ach1, ffmann1, and ´ndez2 1 Institut fu¨r Astronomie und Astrophysik der Universita¨t Mu¨nchen, Scheinerstraße 1, Mu¨nchen, Germany.

Radiation driven winds of hot luminous stars. IX - Constraints on the wind temperature of O-stars Article (PDF Available) January with 8 Reads.

A New Numerical Method for Solving Radiation Driven Winds from Hot Stars Michel Cure´1,⋆ and Diego F. Rial2,1 1 Departamento de F´ısica y Astronom´ıa, Facultad de Ciencias, Universidad de Valpara´ıso, Chile.

2 Departamento de Matema´ticas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.

Among the most massive stars—which tend also to be the hottest and most luminous—the winds can be very strong, with important consequences both for the star’s own evolution as well as for the surrounding interstellar medium. Such hot-star winds are understood to be driven by the pressure of the star’s emitted radiation.

Hot stars emit large amounts of X-rays, which are assumed to originate in the supersonic stellar wind. Part of the emitted X-rays is subsequently absorbed in the wind and influences its ionization state. Because hot star winds are driven radiatively, the.

Get this from a library. Radiation driven winds of hot stars: some remarks on stationary models and spectrum synthesis in time-dependent simulations. [Joachim Puls; United States. National Aeronautics and Space Administration.;].

BibTeX @MISC{Curé07anew, author = {Michel Curé and Diego F. Rial and Key Words}, title = {A New Numerical Method for Solving Radiation Driven Winds from Hot Stars}, year = {}}. Massive stars drive powerful, supersonic winds via the radiative momentum associated with the thermal UV emission from their photospheres.

Shock phenomena are ubiquitous in these winds, heating them to millions, and sometimes tens of millions, of degrees. The emission line spectra from the shock‐heated plasma provide powerful diagnostics of the winds’ physical conditions, which in turn. The theory of radiation-driven wind including stellar rotation is reexamined.

After a suitable change of variables, a new equation for the mass-loss rate is derived analytically. The solution of this equation remains within 1% confidence when compared with numerical solutions.

The velocity law- assumption predicted by the theory of radiation-driven winds (see Castor et al, ; Pauldrach et al, ) B. Šurlan (Astronomical Institute Ondˇrejov) WINDS OF HOT MASSIVE STARS Octo 8 /. Radiation-driven winds of hot luminous stars. XV. Constraints on the mass-luminosity relation of central stars of planetary nebulae.

Autores: A. W. A. Pauldrach Localización: Astronomy and astrophysics: A European journal, ISSNVol.Nº. 3. The topological analysis from Bjorkman () for the standard model that describes the winds from hot stars by Castor et al.

() has been extended to include the effect of stellar rotation and changes in the ionization of the wind. The differential equation for the momentum of the wind is non-linear and transcendental for the velocity gradient. Multicomponent radiatively driven winds in the late B stars cause significant heating of the layers just above the photosphere.

These heated layers form a hot region – a corona, which may provide a significant fraction of energy necessary for the formation of a coronal wind driven .