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