Previous abstract Next abstract

Session 25 - Stars in the Ultraviolet.
Display session, Tuesday, June 10
South Main Hall,

[25.08] Ultraviolet Light Curves, Velocities, and Abundances for the V356 Sagittarii System

S. Roby (S.U.N.Y. Oswego), R. Polidan (NASA/GSFC), D. Armstrong, S. Chruszcz, K. Fraser, J. Hassett, K. E. Mauser (S.U.N.Y. Oswego)

The eclipsing, interacting binary system, V356 Sgr, provides a rare opportunity to directly examine the exposed core of a star for the signatures of nuclear processing. The system is composed of an A2II star which has previously undergone rapid mass transfer to its B3V companion.

We are examining a large number of IUE archival spectra obtained by Dr. Polidan at low and high dispersions with phase coverage through much of the orbit including the eclipse of the B star by the 2.5 times larger A star. Our goal is to use this large data set to examine many aspects of the overall model of this complex system and to determine carbon and other elemental abundances in both stars.

A new orbital velocity for the B star is being determined to improve estimates of the masses in this system. The Rossiter effect exhibited during partial eclipse can be exploited to provide an estimate of the projected rotational velocity of the B star. Light curve models are being developed and compared with low dispersion IUE spectra flux measurements over orbital phase to check for gravitational darkening or reflection effects. Temperature and pressure sensitive Si II and III lines are being examined for possible variations during the orbit and to provide additional checks on the atmospheric parameters of the B star. Abundance analyses of carbon and nitrogen in both stars are just beginning.

This project is supported by a NASA/University Joint Venture (JOVE) grant to SUNY Oswego.

Program listing for Tuesday