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The absolute magnitude of K0V stars from HIPPARCOS parallaxes
R. D. Oudmaijer, M. A. T. Groenewegen, H. Schrijver
We investigate the properties of K0V stars with Hipparcos parallaxes and spectral types taken from the Michigan Spectral Survey. The sample of 200 objects allows the empirical inve…
Carbon stars in populations of different metallicity
M. A. T. Groenewegen
Our current knowledge of carbon stars in the Local Group and beyond, is discussed. Although many carbon stars and late M-stars have been identified in external galaxies a coherent…
New input data for synthetic AGB evolution
J. Wagenhuber, M. A. T. Groenewegen
Analytic formulae are presented to construct detailed secular lightcurves of both early asymptotic giant branch (AGB) and thermally pulsing AGB stars. They are based on an extensiv…
New peculiar CO data of the shell around IRC +10 216
M. A. T. Groenewegen, H. -G. Ludwig
A CO(1-0) on-source spectrum of the well-known carbon star IRC+10216 taken with the IRAM 30m telescope in June 1996 shows excess emission between -18.3 and -14.3 km/s at the red wi…
IRC +10 216 revisited II: the circumstellar CO shell
Martin A. T. Groenewegen, Wil E. C. J. van der Veen, Henry E. Matthews
12CO and 13CO J = 6-5 observations of IRC +10 216 with the JCMT are presented. A spherically symmetric radiative transfer code is used to model these and other CO observations of t…
Fine structure of the red giant clump from HIPPARCOS data, and distance determinations based on its mean magnitude
L. Girardi, M. A. T. Groenewegen, A. Weiss +1
The I-band brightness of clump stars has been used recently to determine the distance to the bulge, the LMC and SMC, and to M31. It was assumed to be a standard candle based on the…
The Lutz-Kelker bias in trigonometric parallaxes
Rene D. Oudmaijer, Martin A. T. Groenewegen, Hans Schrijver
The theoretical prediction that trigonometric parallaxes suffer from a statistical effect, has become topical again now that the results of the Hipparcos satellite have become avai…