IUE Observations of the Pulsation of RY Sgr

Volume 27 number 2 (1999)

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Albert V. Holm

Astronomy Programs

Abstract

The correlation of the onsets of RY Sgr's deep minima with pulsational phase suggests that the formation of dust is somehow driven by the pulsation. Observations were obtained using the International Ultraviolet Explorer (IUE) to investigate whether every pulsation cycle is accompanied by the condensation of small amounts of dust. During the 46-day interval covered by this data set, temperature and geometrical variations contributed 0.85 magnitude and 0.55 magnitude, respectively, to the visual light curve. Dust formation was a smaller effect, but may contribute 0.27 magnitude to the light curve. The phase of maximum extinction found here coincides with the phase at which the deep minima preferentially begin.