Beryllium abundances in Hg-Mn stars
The Hg-Mn stars show anomalous line strengths of many chemical elements including Be. We have observed the Be ii resonance doublet at lambdalambda 3130, 3131 at 6.7 A mm/sup -1/ in 43 Hg-Mn stars and 10 normal stars in the same temperature range with the coude spectrograph of the 2.24 m University of Hawaii telescope at Mauna Kea. Measured equivalent widths of the two lines and/or the blend of the doublet have been compared with predictions from (1) LTE model atmospheres and (2) non-LTE line formation on non-LTE model atmospheres. (For strong Be ii lines, the LTE calculations result in more Be by factors of 2 to 4 than do the non-LTE calculations.) Overabundances of factors of 20--2 x 10/sup 4/ relative to solar have been found for 75% of the Hg-Mn stars. The 25% with little or no Be are typically among the cooler Hg-Mn stars, but for the stars with Be excesses, there is only marginal evidence for a correlationi of the size of the overabundance and temperature. It is suggested that diffusion driven by radiation pressure is responsible for the observed Be abundance anomalies.
- Research Organization:
- Institute for Astronomy, University of Hawaii
- OSTI ID:
- 6699274
- Journal Information:
- Astrophys. J.; (United States), Vol. 259:2
- Country of Publication:
- United States
- Language:
- English
Similar Records
Beryllium in main-sequence stars
SILICON ABUNDANCES IN NEARBY STARS FROM THE Si I INFRARED LINES
Related Subjects
GENERAL PHYSICS
VARIABLE STARS
BERYLLIUM
ABUNDANCE
BERYLLIUM IONS
CHEMICAL COMPOSITION
LTE
STELLAR ATMOSPHERES
VISIBLE SPECTRA
ALKALINE EARTH METALS
ATMOSPHERES
CHARGED PARTICLES
ELEMENTS
EQUILIBRIUM
IONS
METALS
SPECTRA
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources