skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: SEISMOLOGICAL TESTS OF THE DIFFUSION/MASS-LOSS THEORY FOR LAMBDA BOOTIS STARS

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
786209
Report Number(s):
LA-UR-99-6135
TRN: US200307%%611
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Nov 1999
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; VALIDATION; MATHEMATICAL MODELS; STARS; DIFFUSION; MASS; LOSSES

Citation Formats

C. NEUFORGE-VERHEECKE, J. A. GUZIK, and P. A. BRADLEY. SEISMOLOGICAL TESTS OF THE DIFFUSION/MASS-LOSS THEORY FOR LAMBDA BOOTIS STARS. United States: N. p., 1999. Web.
C. NEUFORGE-VERHEECKE, J. A. GUZIK, & P. A. BRADLEY. SEISMOLOGICAL TESTS OF THE DIFFUSION/MASS-LOSS THEORY FOR LAMBDA BOOTIS STARS. United States.
C. NEUFORGE-VERHEECKE, J. A. GUZIK, and P. A. BRADLEY. 1999. "SEISMOLOGICAL TESTS OF THE DIFFUSION/MASS-LOSS THEORY FOR LAMBDA BOOTIS STARS". United States. doi:. https://www.osti.gov/servlets/purl/786209.
@article{osti_786209,
title = {SEISMOLOGICAL TESTS OF THE DIFFUSION/MASS-LOSS THEORY FOR LAMBDA BOOTIS STARS},
author = {C. NEUFORGE-VERHEECKE and J. A. GUZIK and P. A. BRADLEY},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1999,
month =
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • It has recently been suggested that the peculiar abundance patterns observed in the Lambda Bootis stars could be understood in terms of accretion of gas previously depleted in metals by means of grain formation in the interstellar medium. A simple analytical model is presented, describing the evolution of elemental abundances in these stars, under the combined influence of accretion and chemical separation. The only arbitrary parameter involved is the accretion rate. A rate of order 10 to the {minus}13th solar mass/yr is found to naturally reproduce many peculiar characteristics of Lambda Bootis stars, in particular their restriction to the spectralmore » type range A0{minus}F0. This lends quantitative support to the accretion hypothesis as a key component toward an understanding of the Lambda Bootis phenomenon. 18 refs.« less
  • Abundance analyses are reported for three certain members (Lambda Boo, 29 Cyg, Pi1 Ori) of the class of rapidly rotating, metal-poor A-type stars known as Lambda Bootis stars. Model atmosphere analysis of high-resolution, high signal-to-noise spectra shows that the metal deficiencies are more severe than previously reported: Fe/H = -2.0, -1.8, -1.3 for Lambda Boo, 29 Cyg, and Pi1 Ori, respectively. Other metals (Mg, Ca, Ti, and Sr) are similarly underabundant, with Na often having a smaller underabundance. C, N, O, and S have near-solar abundances. Vega is shown to be a mild Lambda Boo star. The abundance anomalies ofmore » the Lambda Boo stars resemble those found for the interstellar gas in which the metals are depleted through formation of interstellar grains. It is suggested that the Lambda Boo stars are created when circumstellar (or interstellar) gas is separated from the grains and accreted by the star. The bulk of the interstellar grains comprises a circumstellar cloud or disk that is detectable by its infrared radiation. 67 refs.« less
  • A numerical hydrodynamics code is used to investigate two aspects of the winds of hot stars. The first is the question of the instability of the massive radiatively-driven wind of an O star that is caused by the line shape mechanism: modulation of the radiation force by velocity fluctuations. The evolution of this instability is studied in a model O star wind, and is found, /ital modulo/ some numerical uncertainty, to lead to wave structures that are compatible with observations of wind instabilities. The other area of investigation is of main-sequence B star winds. Attempts were made to simulate amore » radiatively-driven and a pulsation-driven wind in a B star, but in each case the wind turned out to be very weak. It is argued that the pulsation-driven wind model is not likely to apply to B stars. 28 refs., 11 figs.« less