The sub-arcsecond dusty environment of Eta Carinae
The core of the nebula surrounding Eta Carinae has been observed withthe VLT Adaptive Optics system NACO and with the interferometerVLTI/MIDI to constrain spatially and spectrally the warm dustyenvironment and the central object. In particular, narrow-band images at3.74 μm and 4.05 μm reveal the butterfly shaped dusty environmentclose to the central star with unprecedented spatial resolution. A voidwhose radius corresponds to the expected sublimation radius has beendiscovered around the central source. Fringes have been obtained in theMid-IR which reveal a correlated flux of about 100 Jy situated 0.3arcsec south-east of the photocenter of the nebula at 8.7 μm, whichcorresponds with the location of the star as seen in other wavelengths.This correlated flux is partly attributed to the central object, andthese observations provide an upper limit for the SED of the centralsource from 2.2 μm to 13.5 μm. Moreover, we have been able tospectrally disperse the signal from the nebula itself at PA = 318degree, i.e. in the direction of the bipolar nebula (~310°) withinthe MIDI field of view of 3 arcsec. A large amount of corundum (Al2O3)is discovered, peaking at 0.6 arcsec-1.2 arcsec south-east from thestar, whereas the dust content of the Weigelt blobs is dominated bysilicates. We discuss the mechanisms of dust formation which are closelyrelated to the geometry of this Butterfly nebulae.
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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
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Sinusoidal variables from the Tycho Epoch Photometry Annex
The Tycho Epoch Photometry Annex A, a data base of photometry of morethan 34 000 bright stars, has been searched for periodic variablestars with approximately sinusoidal light curves. Advantage was taken ofspecial properties of the observing programme (photometry in twowavebands, availability of repeated measurements) to use simple butefficient variable selection criteria. Details of 70 strong candidatevariables are presented.
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On Identifications of New Variable Stars Announced by Woitas
Confusion in the positions of variable stars announced in IBVS No. 4444has been clarified.
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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.
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Stellar radii of M giants
We determine the stellar radii of the M giant stars in the Hipparcoscatalogue that have a parallax measured to better than 20% accuracy.This is done with the help of a relation between a visual surfacebrightness parameter and the Cousins (V - I) colour index, which wecalibrate with M giants with published angular diameters.The radii of(non-Mira) M giants increase from a median value of 50 R_Sun at spectraltype M0 III to 170 R_Sun at M7/8 III. Typical intermediate giant radiiare 65 R_Sun for M1/M2, 90 R_Sun for M3, 100 R_Sun for M4, 120 R_Sun forM5 and 150 R_Sun for M6. There is a large intrinsic spread for a givenspectral type. This variance in stellar radius increases with latertypes but in relative terms, it remains constant.We determineluminosities and, from evolutionary tracks, stellar masses for oursample stars. The M giants in the solar neighbourhood have masses in therange 0.8-4 M_Sun. For a given spectral type, there is a close relationbetween stellar radius and stellar mass. We also find a linear relationbetween the mass and radius of non-variable M giants. With increasingamplitude of variability we have larger stellar radii for a given mass.
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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.
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Detection of 43 New Bright Variable Stars by the TYCHO Instrument of the HIPPARCOS Satellite
Not Available
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Valinhos 2.2 micron survey of the southern galactic plane. II - Near-IR photometry, IRAS identifications and nature of the sources
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987A&AS...71...39E&db_key=AST
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IRAS catalogues and atlases - Atlas of low-resolution spectra
Plots of all 5425 spectra in the IRAS catalogue of low-resolutionspectra are presented. The catalogue contains the average spectra ofmost IRAS poiont sources with 12 micron flux densities above 10 Jy.
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Spectroscopic and Photometric Observations of M Supergiants in Carina.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...172...75H&db_key=AST
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An infrared survey of the region of SA 193
Abstract image available at:http://adsabs.harvard.edu/abs/1965MNRAS.130...45W
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Estrellas Rojas entre Popa y Cruz.
Not Available
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