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Stellar radii of M giants
Schild, H.; Dumm, T.
We determine the stellar radii of the M giant stars in the Hipparcos catalogue3 that have a parallax measured to better than 20% accuracy. This is done with the help of a relation between a visual surface brightness parameter and the Cousins ( V - I) colour index, which we calibrate with M giants with published angular diameters. The ra…
The Coma Berenices star cluster and its moving group
Soubiran, C.; Odenkirchen, M.; Colin, J.
We report on the analysis of astrometric and photometric data from Hipparcos, Tycho and the ACT catalogue in a 1200 sq. degree field around the nearby open star cluster in Coma Berenices and infer the characteristic features of this cluster. From a sample of 51 kinematic members we derive the cluster's distance, size and spatial structure as well …
Hipparcos data for two open clusters containing cepheids
Lindegren, L.; Lyngå, G.
Using proper motion data from the Hipparcos satellite it is shown that the cepheids S Nor and U Sgr are members of the open clusters NGC 6087 and M 25, respectively. The precision of the Hipparcos data is needed to conclusively carry out a membership test. Parallax data, also obtained from Hipparcos, do not contradict the proper motion results.