Previous abstract Next abstract

Session 59 - Pulsating/Variable Stars.
Display session, Wednesday, June 12
Great Hall,

[59.06] Use of Temperature-Sensitive Line Ratios for Stellar Seismology

R. W. Noyes, M. S. G. Korzennik, Krockenberger, P. Nisenson (CfA), T. Brown, T. Kennelly (HAO), S. Horner (Penn. State U.)

The line depths of virtually all stellar spectral lines are sensitive to small changes in stellar temperature T_eff induced by pulsations, with varying degrees (and signs) depending on the mean T_eff and the line ionization and excitation state. For large-amplitude pulsators, such as Cepheids, temperatures obtained from individual line pairs are sufficiently accurate and invariant to reddening to play an important role in distance measurements. For small-amplitude pulsators, this technique is inadequate. However, by combining the information from a very large number of spectral lines recorded with high spectral resolution, such as can be provided by a cross-dispersed echelle spectrograph, it should be possible to measure temperature changes to a precision considerably greater than can be obtained by comparing single pairs of lines. We explore this possibility by using a grid of synthetic stellar spectra to provide the run of temperature sensitivity as a function of wavelength throughout the spectrum, and make specific application to spectra obtained with the Advanced Fiber Optic Echelle (AFOE) spectrograph.

Program listing for Wednesday