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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
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| Water vapor absorption in early M-type stars
The spectrometers onboard the Infrared Telescope in Space (IRTS) revealwater vapor absorption in early M-type stars, as early as M2. Previousobservations detected H_2O vapor absorption only in stars later than M6,with the exception of the recent detection of H_2O in betaPeg (M2.5 II-III). In our sample of 108 stars, 67 stars havespectral types earlier than M6. The spectral types are established bymeans of their near-infrared colors on a statistical basis. Among the 67stars of spectral types earlier than M6, we find water vapor absorptionin six stars. The observed absorption features are interpreted using alocal thermodynamic equilibrium model. The features are reasonablyfitted by model spectra with excitation temperatures of 1000-1500 K andwater column densities of 5*E(19) to 1*E(20) cm(-2) . These numbersimply that the H_2O molecules are present in a region of the atmosphere,located above the photosphere. Furthermore, our analysis shows a goodcorrelation between the H_2O absorption band strength, and themid-infrared excess due to the circumstellar dust. We discuss therelation between the outer atmosphere and the mass loss.
| Hipparcos: The Stars
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| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| Classification and Identification of IRAS Sources with Low-Resolution Spectra
IRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed.
| 35 new bright medium- and high-amplitude variables discovered by the TYCHO instrument of the HIPPARCOS satellite
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Osservazione e dati astrometrici
| Costellazione: | Microscopio |
| Ascensione retta: | 21h25m28.36s |
| Declinazione: | -41°42'07.3" |
| Magnitudine apparente: | 7.666 |
| Distanza: | 304.878 parsec |
| Moto proprio RA: | 21.6 |
| Moto proprio Dec: | 1.7 |
| B-T magnitude: | 9.656 |
| V-T magnitude: | 7.831 |
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