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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
| Really Cool Stars at the Galactic Center
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.1988B&db_key=AST
| Galactic bulge M giants. IV - 0.5-2.5 micron spectrophotometry and abundances for stars in Baade's Window
Spectrophotometric observations of bulge and local M giants from 0.45 to2.5 microns at a resolution of about 1000 are presented. From ananalysis of strong atomic lines of Na I and Ca I in the K band, a meanmetallicity of the M giants in Baade's Window is derived. It isdemonstrated that J-K is a good temperature indicator for both the fieldand bulge nonvariable M giants, and that the relationship between thetwo quantities is the same for both types of stars. In addition, thereis no difference in the surface gravity between bulge and field giantsof the same J-K color (i.e., temperature). A major difference in theoverall spectral energy distributions of bulge and local M giants isthat the classical H-band bump attributed to the opacity minimum of theH(-) ion near 1.6 microns is considerably reduced in many of the bulgestars.
| Galactic bulge M giants. III - Near-infrared spectra and implications for the stellar content of E and S0 galaxies
Spectra at 0.6-0.9 micron of 320 K and M giants in six low-absorptionfields along the minor axis of the galactic bulge and of an additional60 late-type giants and dwarfs in the solar neighborhood were obtained.Indices of the strength of molecular absorption are combined withprevious infrared and optical photometry to estimate the mean metalabundance of the bulge M giants and to constrain the relativecontribution of late giants and dwarfs to the integrated light of E andS0 galaxies.
| M giants in Baade's window - Infrared colors, luminosities, and implications for the stellar content of E and S0 galaxies
In this paper, 1-10 micron photometric observations of M giants inBaade's window are presented and interpreted. When compared to solarneighborhood M giants, it is found that: (1) bulge giants at the samespectral type have bluer JHK colors but stronger CO indices; (2) thenearly dispersionless H-H, H-K relation for the bulge giants lies on theopposite side of the mean field giant relation from that for globularcluster stars; and (3) bulge M giants are up to two magnitudes fainterthan field giants of the same spectral type, and their luminosityfunction drops precipitously for M(bol) brighter than -4.2. It is arguedthat the near-infrared energy distribution of the bulge giants isstrongly affected by molecular blanketing, particularly from H2O.Long-period variables have infrared colors and indices which give themphotometric properties distinct form all other M giants in Baade'swindow. The observed characteristics of the bulge M giants areconsistent with their being representatives of a population with ametallicity considerably in excess of solar.
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Osservazione e dati astrometrici
| Costellazione: | Centauro |
| Ascensione retta: | 11h34m13.26s |
| Declinazione: | -39°56'23.4" |
| Magnitudine apparente: | 8.137 |
| Distanza: | 531.915 parsec |
| Moto proprio RA: | -20.1 |
| Moto proprio Dec: | 6.8 |
| B-T magnitude: | 10.144 |
| V-T magnitude: | 8.303 |
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