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.
|
Infrared Properties of SiO Maser Sources in Late-Type Stars
The results of an SiO maser survey for late-type stars selected by theIRTS (Infrared Telescope in Space) are presented. We have detected SiOJ=1-0, v=1 and/or v=2 lines in 27 stars out of 59 stars. The maserintensity increases with the depth of the H_2O absorption in theinfrared spectra and redness of the 2.2 and 12 mu m color. The columndensities of the water vapor in the target stars were estimated from thedepth of the water absorption in the IRTS spectra. We found that the SiOmaser was detected mostly in the stars with a column density of watervapor higher than 3*E19-3*E20 cm-2. Wefurther estimated the density of hydrogen molecules in the outeratmosphere corresponding to these column densities, obtaining109-1010 cm-3 as a lower limit. Thesevalues are roughly in agreement with the critical hydrogen densitypredicted by models for the excitation of SiO masers. It is possiblethat the SiO masers are excited in clumps with column density evenhigher than this value. The present results provide useful informationfor the understanding of the physical conditions of the outeratmospheres in late-type stars.
|
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 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.
|
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.
|
A Search for S-Stars in the IRC and AFGL Catalogues
Seventeen unidentified sources contained in the 2jt JR Catalogue, andAFGL-AFGLS Catalogues have been tentatively indicated as S stars from acomparison with the General Catalogue of S stars. An analysis based onthe I - K and K - [4.2j.~] behavior has been performed for all thesources which have been found to be in common with all the abovementioned catalogues. The results lead to the conclusion that thepresence of circumstellar shells seems to be very unlike for theseobjects in spite of their evolutionary status which is intermediatebetween M and C type stars
|
