FG Sagittae - 1975 to 1978
The spectrum of the extremely peculiar variable star, FG Sagittae, has been followed with high dispersion over the interval from 1975 to 1978, thus continuing the work of Herbig and Boyarchuk and of Langer, Kraft, and Anderson. A new technique for crude abundance determinations is presented. Using the spectrum ratio method, we find that the steady increase in the s-process element abundances, which began in approximately 1964, has ceased. A cooling of only 500 K is permitted over the 3 years of our observations, at least on the specific dates we observed the star. The agreement between convective time scales derived from a simple application of the mixing length theory and the observed time scale for the s-process episode implies that this event occurred as a result of a convective zone penetrating for a short time into a region where s-process nucleosynthesis had already occurred.
Additional Information© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1979 April 2; accepted 1979 October 4. We thank Juliana Sackmann and Robert Kraft for helpful conversations. We grant absolution to the anonymous referee whose criticism forced us to work harder and greatly improved this paper.
Published - 1980ApJ___237___99C.pdf