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Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/397/997
| A photometric study of K and M dwarf stars found by Stephenson
Broadband photometry has been obtained for a sample of the K and M dwarfstars found in an objective prism survey by Stephenson (1986). Among thestars with unknown proper motion, about 24 percent of those observedappear from the photometry not to be dwarfs, although the percentagevaries considerably with spectral type. For stars with V less than 11.5and B - V equal to or greater than 1.2, it is estimated that, within thearea surveyed, Stephenson's survey is about 68 percent complete.
| Dwarf K and M stars of small proper motion found in a large spectroscopic survey
More than 2000 candidates for K and M dwarf status, generally havingproper motions that are either unknown or less than 0.2 arcsec perannum, have been identified in an objective-prism survey covering theentire sky north of declination - 25 degrees and more than 10 degreesfrom the galactic plane. More than 95 percent have no previousindication that they are dwarfs. Several dozen appear to be visualdouble stars.
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