Date of Award
1993
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
Abundances of 15 elements have been determined for 16 early A-type stars, 14 of which are classified as normal. Abundances have been determined for Sirius, a hot Am star, and {dollar}\lambda{dollar} Boo, the prototypical member of its class. These stars range in vsini from 6 to 114 km s{dollar}\sp{lcub}-1{rcub}.{dollar} Spectrum synthesis has been used to determine the abundances. It is shown to be reliable and capable of application to even broader lined stars. Despite the fact that most of the stars studied are classified as normal, they exhibit a considerable range of abundances. The abundances of most elements scale (at least roughly) with those of iron, which ranges over more than 0.7 dex among supposedly normal stars. Carbon is probably anti-correlated with iron while calcium exhibits a more complex behaviour. Helium seems constant and slightly underabundant with respect to the sun. Elements heavier than iron generally show an enhancement with respect to the sun. Correlations of the abundances with various stellar parameters are studied. For some elements the average abundance is roughly solar (e.g. iron) while for others it is not (e.g. the heavy elements). The range of abundances exhibited by most elements is wide enough that there seems to be a continuous distribution of abundances from those of the Am stars through the normal stars. The {dollar}\lambda{dollar} Boo stars may be the low abundance tail of this distribution.
Recommended Citation
Hill, Grant Michael, "What Is Normal Among The A-type Stars?" (1993). Digitized Theses. 2272.
https://ir.lib.uwo.ca/digitizedtheses/2272