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