EDP Sciences
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Volume 397, Number 3, January III 2003
Page(s) 997 - 1010
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20021589

A&A 397, 997-1010 (2003)
DOI: 10.1051/0004-6361:20021589

Hipparcos red stars in the $HpV_{\rm T2}$ and $V\!I_{\rm C}$ systems

I. Platais1, 2, D. Pourbaix1, A. Jorissen1, V. V. Makarov2, 3, L. N. Berdnikov4, N .N. Samus5, 4, T. Lloyd Evans6, T. Lebzelter7 and J. Sperauskas8

1  Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Bruxelles, Belgium
2  Universities Space Research Association, Division of Astronomy and Space Physics, 300 D Street SW, Washington, D.C. 20024, USA
3  U.S. Naval Observatory, 3450 Massachusetts Ave., NW, Washington D.C. 20392-5420, USA
4  Sternberg Astronomical Institute and Isaac Newton Institute of Chile, Moscow Branch, 13 Universitetskij Prosp., Moscow 119992, Russia
5  Institute of Astronomy, Russian Academy of Sciences, 48 Pyatnitskaya Str., Moscow 119017, Russia
6  School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, Scotland KY16 9SS
7  Institut für Astronomie, Universität Wien, Türkenschanzstr. 17, 1180 Vienna, Austria
8  Vilnius University Observatory, Ciurlionio 29, Vilnius 2009, Lithuania

(Received 20 September 2002 / Accepted 28 October 2002 )

For Hipparcos M, S, and C spectral type stars, we provide calibrated instantaneous (epoch) Cousins $V\!-\!I$ color indices using newly derived $HpV_{\rm T2}$ photometry. Three new sets of ground-based Cousins $V\!I$ data have been obtained for more than 170 carbon and red M giants. These datasets in combination with the published sources of $V\!I$ photometry served to obtain the calibration curves linking Hipparcos/Tycho $Hp-V_{\rm T2}$ with the Cousins $V\!-\!I$ index. In total, 321 carbon stars and 4464 M- and S-type stars have new $V\!-\!I$ indices. The standard error of the mean $V\!-\!I$ is about 0.1 mag or better down to $Hp\approx9$ although it deteriorates rapidly at fainter magnitudes. These $V\!-\!I$ indices can be used to verify the published Hipparcos $V\!-\!I$ color indices. Thus, we have identified a handful of new cases where, instead of the real target, a random field star has been observed. A considerable fraction of the DMSA/C and DMSA/V solutions for red stars appear not to be warranted. Most likely such spurious solutions may originate from usage of a heavily biased color in the astrometric processing.

Key words: stars: late type -- stars: carbon -- techniques: photometric -- techniques: radial velocities

Offprint request: D. Pourbaix, pourbaix@astro.ulb.ac.be

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