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HIPPARCOS VERSUS GCVS AMPLITUDES OF NON-MIRA

M-TYPE GIANTS

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Dorrit Hoffleit

Department of Astronomy

Yale University

New Haven, CT 06520-8101

Presented at the 87th Annual Meeting of the AAVSO, October 31, 1998

Abstract

A recent paper by Dumm and Schild deals with the determination of radii and masses for Hipparcos stars with non-Mira giant M-type spectra. Their list contains 350 stars, of which 205 are either verified or suspected variables, including 53 SR (semiregular) and 51 Lb (irregular) variables. The authors determined that the masses and radii of the non-variable stars show a clear correlation, whereas the variable stars deviate from this relation roughly according to their amplitudes. In comparing the Hipparcos amplitudes with the amplitudes in the GCVS and NSV I found numerous conspicuous discordances, ranging well over a whole magnitude. I therefore hoped that the older amplitudes, based in general upon data more specifically obtained for period determination, might improve the scatter in the Dumm and Schild diagram, but this is not the case. In the course of the investigation, numerous stars were encountered that merit further observations. Two were found of especial interest: V370 And, discovered by Hipparcos, and l Dra, with a reputed period of 1100 days.

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