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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
| SiO maser survey of AGB stars in the North Galactic Cap
A SiO maser survey in the J=1-0, v=1 and 2 transitions has been made forIRAS sources in the North Galactic Cap b > 30o) with theNobeyama 45 m radio telescope. The sources were selected on the basis oftheir IRAS 12/25-μm and 25/60-μm flux ratios as likely oxygen-richAGB candidates. SiO masers were detected from 24 out of the 97 selectedsources, where 17 were new detections. The distances and heights abovethe Galactic plane are calculated. The Galactic distribution of detectedand undetected stars indicates that metallicity is likely to govern thedetection rate. The Galactocentric angular velocities of the subsampledstars are derived and their variation with the Galactic height isdiscussed. Based on observations at the Nobeyama Radio Observatory(NRO). NRO is a branch of the National Astronomical Observatory, aninter-university research institute, operated by the Ministry ofEducation, Science and Culture, Japan.
| 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.
| Speckle Interferometry of New and Problem HIPPARCOS Binaries
The ESA Hipparcos satellite made measurements of over 12,000 doublestars and discovered 3406 new systems. In addition to these, 4706entries in the Hipparcos Catalogue correspond to double star solutionsthat did not provide the classical parameters of separation and positionangle (rho,theta) but were the so-called problem stars, flagged ``G,''``O,'' ``V,'' or ``X'' (field H59 of the main catalog). An additionalsubset of 6981 entries were treated as single objects but classified byHipparcos as ``suspected nonsingle'' (flag ``S'' in field H61), thusyielding a total of 11,687 ``problem stars.'' Of the many ground-basedtechniques for the study of double stars, probably the one with thegreatest potential for exploration of these new and problem Hipparcosbinaries is speckle interferometry. Results are presented from aninspection of 848 new and problem Hipparcos binaries, using botharchival and new speckle observations obtained with the USNO and CHARAspeckle cameras.
| 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.
| A survey of circumstellar CO emission from a sample of IRAS point sources
The first results from a survey of circumstellar CO(1-0) emission arepresented. The sources were selected from the IRAS point source catalogaccording to the IRAS color criteria described in van der Veen andHabing (1988). The sources have good quality fluxes at 12, 25, and 60microns, flux densities larger than 20 Jy at 25 microns, and aresituated more than 5 deg away from the Galactic plane. The survey isundertaken to study the relationship between mass loss rates, dustproperties, and the evolution along the AGB. The sample consists of 787sources and contains both oxygen and carbon-rich stars, including Miravariables, OH/IR objects, protoplanetary nebulae, planetary nebulae, and60-micron excess sources. So far, 519 objects, situated on both thenorthern and the southern sky, have been observed; 163 sources werefound to have circumstellar CO emission, and in 58 of these CO emissionhas not previously been detected.
| A survey for infrared excesses among high galactic latitude SAO stars
This project involves extending the previous analysis of infraredexcesses among a volume-limited sample of 134 nearby A-K main-sequencestars to a magnitude-limited sample of stars, culled from the SAOCatalog, with excesses determined from the IRAS Point Source Catalogflux density ratios. This new sample includes 5706 B-M type stars, 379of which have infrared excesses. The objective involved use of astatistically complete survey of objects in a standard catalog in orderto assess the frequency with which different physical processes canaffect the infrared output of stars. These processes include, but arenot limited to, orbiting cold particle clouds and the onset of rapidmass loss. It is concluded that cold disks are consistent with theinfrared excesses found among A-G dwarfs and G-K giants in the sample.
| New LRS spectra for 356 bright IRAS sources
The low-resolution spectra of all IRAS point sources with F(nu) (12microns) greater than 40 Jy that were not included in the Atlas ofLow-Resolution Spectra are presented. These have been classified intoeight groups based upon the spectral morphology. Silicate emissionspectra and red-continuum spectra associated with H II region sourcesform about 60 percent of this sample. All types of spectra in the LRSAtlas are represented in the sample except for emission-line sources.The sample is used to test a recent classification scheme for IRASsources based on broadband colors. The spectra is used to test a recentclassification scheme for IRAS sources based on broadband colors. Thespectra are consistent with the classifications from the colors in mostcases.
| The brightest high-latitude 12-micron IRAS sources
The Infrared Astronomical Satellite (IRAS) Point Source catalog wassearched for sources brighter than 28 Jy (0 mag) at 12 microns withabsolute galactic latitude greater than 30 deg excluding the LargeMagellanic Cloud. The search resulted in 269 sources, two of which arethe galaxies NGC 1068 and M82. The remaining 267 sources are identifiedwith, or have infrared color indices consistent with late-type starssome of which show evidence of circumstellar dust shells. Seven sourcesare previously uncataloged stars. K and M stars without circumstellardust shells, M stars with circumstellar dust shells, and carbon starsoccupy well-defined regions of infrared color-color diagrams.
| Catalogue d'étoiles variables nouvelles
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