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

Title: Revising the Evolutionary Stage of HD 163899: The Effects of Convective Overshooting and Rotation

Abstract

We revise the evolutionary status of the B-type supergiant HD 163899 based on the new determinations of the mass–luminosity ratio, effective temperature, and rotational velocity, as well as on the interpretation of the oscillation spectrum of the star. The observed value of the nitrogen-to-carbon abundance fixes the value of the rotation rate of the star. Now, more massive models are strongly preferred than those previously considered, and it is very likely that the star is still in the main-sequence stage. The rotationally induced mixing manifests as the nitrogen overabundance in the atmosphere, which agrees with our analysis of the HARPS spectra. Thus, HD 163899 probably belongs to a group of evolved nitrogen-rich main-sequence stars.

Authors:
; ;  [1]
  1. Instytut Astronomiczny, Uniwersytet Wrocławski, ul. Kopernika 11, 51-622 Wrocław (Poland)
Publication Date:
OSTI Identifier:
22663965
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ATMOSPHERES; CARBON; LUMINOSITY; MAIN SEQUENCE STARS; MASS; MIXING; OSCILLATIONS; ROTATION; SPECTRA

Citation Formats

Ostrowski, Jakub, Daszyńska-Daszkiewicz, Jadwiga, and Cugier, Henryk, E-mail: ostrowski@astro.uni.wroc.pl. Revising the Evolutionary Stage of HD 163899: The Effects of Convective Overshooting and Rotation. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/2/290.
Ostrowski, Jakub, Daszyńska-Daszkiewicz, Jadwiga, & Cugier, Henryk, E-mail: ostrowski@astro.uni.wroc.pl. Revising the Evolutionary Stage of HD 163899: The Effects of Convective Overshooting and Rotation. United States. doi:10.3847/1538-4357/835/2/290.
Ostrowski, Jakub, Daszyńska-Daszkiewicz, Jadwiga, and Cugier, Henryk, E-mail: ostrowski@astro.uni.wroc.pl. Wed . "Revising the Evolutionary Stage of HD 163899: The Effects of Convective Overshooting and Rotation". United States. doi:10.3847/1538-4357/835/2/290.
@article{osti_22663965,
title = {Revising the Evolutionary Stage of HD 163899: The Effects of Convective Overshooting and Rotation},
author = {Ostrowski, Jakub and Daszyńska-Daszkiewicz, Jadwiga and Cugier, Henryk, E-mail: ostrowski@astro.uni.wroc.pl},
abstractNote = {We revise the evolutionary status of the B-type supergiant HD 163899 based on the new determinations of the mass–luminosity ratio, effective temperature, and rotational velocity, as well as on the interpretation of the oscillation spectrum of the star. The observed value of the nitrogen-to-carbon abundance fixes the value of the rotation rate of the star. Now, more massive models are strongly preferred than those previously considered, and it is very likely that the star is still in the main-sequence stage. The rotationally induced mixing manifests as the nitrogen overabundance in the atmosphere, which agrees with our analysis of the HARPS spectra. Thus, HD 163899 probably belongs to a group of evolved nitrogen-rich main-sequence stars.},
doi = {10.3847/1538-4357/835/2/290},
journal = {Astrophysical Journal},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • The overshooting in the framework of the turbulent convection model is investigated in the solar overshooting region. The overshooting mixing is treated as a diffusive process. It is found that the sound speed profile can be improved to be in good agreement with helioseismic inversions. The bump in the sound speed differences between solar models and the helioseismical inversions below the base of the solar convective envelope is almost eliminated by the overshooting mixing. The overshooting mixing leads to a significant depletion of Li in the main-sequence stage. Li abundance in the solar surface can be reduced to about 1%more » of its initial abundance in the solar models with the overshooting mixing. The solar model with the overshooting shows a smooth profile of the temperature gradient, which is also favored by the helioseismology.« less
  • Models of AGB evolution of intermediate mass stars are constructed that take into account overshooting by extrapolating models by Bertelli et al. (1985). Models with overshooting show an increased importance of second dredge-up compared with standard models. He production is increased, allowing dY/dZ to increase by roughly 0.7. Secondary N production is also increased in a way that can explain the observed N/O versus O diagram. Overshooting decreases the theoretical minimum mass for the formation of type I planetary nebulae (PN) down to roughly 2.6 solar masses, in good agreement with the observed value of 2.4 solar masses. Other effectsmore » of overshooting in type I PN are He/H abundances as high as 0.22 and higher depletion of O. 19 references.« less
  • Overshooting of convective elements far beyond the classical Schwarzschild convective core boundary in theoretical models of massive ZAMS stars is found to lead to significant reductions of stellar luminosity and radius, provided that the temperature gradient in the overshoot region can be approximated by the adiabatic gradient. Comparison of these theoretical models with binary star data for the range of 5-15 solar masses indicates that the ratio of overshoot distance to pressure scale height is probably less than 1.5. This result apparently excludes any overshooting theories that predict very extended adiabatic convective cores. 47 refs.