|New periodic variables from the Hipparcos epoch photometry|
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
|A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars|
Rotational velocity vsin i and mean radial velocity are presented for asample of 231 Ib supergiant stars covering the spectral region F, G andK. This work is the second part of the large survey carried out with theCORAVEL spectrometer to establish the behavior of the rotation for starsevolving off the main sequence (De Medeiros & Mayor 1999). Thesedata will add constraints to the study of the rotational behavior inevolved stars, as well as solid information concerning tidalinteractions in binary systems and on the link between rotation,chemical abundance and activity in stars of intermediate masses. Basedon observations collected at the Haute-Provence Observatory,Saint-Michel, France and at the European Southern Observatory, La Silla,Chile Table 1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/395/97
|Quantitative spectral classification of galactic disc K-M stars from spectrophotometric measurements|
New spectral observations for 47 southern galactic red supergiantsobtained with the new RUBIKON spectrophotometer (developed at theAstronomisches Institut der Ruhr-Universitat Bochum) at the Bochum 61-cmtelescope on La Silla are presented. The spectra range from 4800 to 7700A and their resolution is 10 A. The mean error of absolute fluxes is0.028 mag and that of relative fluxes 0.021 mag. The spectra will beavailable at the Strasbourg Stellar Database (CDS). Together with datataken from recently published spectral catalogues, the new observationshave been used to define spectral indices as measures of the strengthsof the following features: Fe i+TiOalpha_1, Mgb+TiOalpha_0,NaD+TiOgamma'_1, TiOgamma'_0 and TiOgamma_1 systems. The indices havebeen checked against errors introduced by reductions, interstellarreddening and different resolutions of different spectral catalogues,and have been found to be very insensitive to all these effects.Therefore, different catalogues may be combined without any loss ofaccuracy and homogeneity. The mean error of a single index has beenfound to be 0.011 mag. For stars from K4 to M7, a strong temperaturedependence is found for all indices. For the Fe i+TiO and especially theMgb+TiO features, a strong dependence on luminosity has also beenobserved. These indices therefore have been combined to form aluminosity index, while the others together form a spectral index. Thecombined indices have been calibrated in terms of MK data using thestepwise linear regression technique, and may be used for quantitativetwo- dimensional spectral classification of late K- and M-type stars.The mean error of the classification is 0.6 of spectral subtype and 0.8of luminosity class, which is much higher than would be expected fromthe uncertainty of the indices alone (which, e.g., for an M4 giantcorrespond to an uncertainty of 0.1 of spectral subtype and 0.3 ofluminosity class). This may be explained by the uncertainty of theoriginal MK classifications and the variability of some programme stars.
|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.
|Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.|
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
|CCD observations of the H-alpha line in late G and K supergiants and their interpretation|
CCD echelle spectra of the H-alpha line at 6563 A have been obtained fora sample of 30 G and K supergiants with a spectral resolution of about0.24 A. The data clearly indicate that the observed H-alpha profile is adeep absorption, implying large optical depths in the chromosphere.Also, the line cores are blueshifted in all the stars which suggests thechromospheres are expanding outward. Detailed radiative transfercalculations of H-alpha have been carried out in a spherically symmetricatmosphere with outward-positive velocity and temperature gradients,including explicitly the effects of ionization. The H-alpha lineprofiles have been computed for a wide range of parameters in order toreproduce the observed features of the line. Within the framework of ourmodel, the calculations reinforce the idea that the nonthermalvelocities have to be as large as 25-30 km/s to explain the large widthsof the observed profiles. The rates of mass outflow have been calculatedto lie in the range 10 exp -8 to 10 exp -9 solar mass/yr.
|Photometry of F-K type bright giants and supergiants. I - Intermediate band and H-Beta observations|
Over 1500 observations of 560 bright giants and supergiants of types F-Kare presented and compared to the observations by Gray and Olsen (1991).The present results include intermediate-band which is slightlydifferent from the Stromgren data by Gray and Olsen due to a differentwidth for the v filter. A systematic difference in m(1) - M(1) withdecreasing temperature is noted in the two H-Beta data sets, and thecorrelations are defined.
|Third list of corrections to the identifications of IRAS sources in Astron. & Astrophys Suppl. 65, 607 and Astron. J. 98, 931|
|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.
|UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.|
|Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample|
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
|The Perkins catalog of revised MK types for the cooler stars|
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
|Consequences of a chromospheric temperature rise on the formation of the H-alpha line in late-type supergiants|
Computations of the H-alpha line profiles were performed in a non-LTEmoving chromosphere with temperature rise to simulate the observedH-alpha characteristics in G and K supergiants. The comoving frameradiative transfer code was modified to incorporate explicitly theeffects of hydrogen ionization. The sensitivity of H-alpha profiles to avariety of temperature structures, velocity gradients, and chromosphericextents and densities is examined and illustrated. Comparison of theobserved profiles to computed ones gives total hydrogen densities in therange between 10 to the 9th and 10 to the 11th/cu cm at the base of theline forming region. Integrated chromospheric optical depths in therange of 50-5000 and expansion velocities in the range of 0.25-2 timesthe maximum random (microturbent and thermal) velocity are found. Themass loss rate is inferred to be in the range between 10 to the -7th and10 to the -9th solar masses/year.
|Expanding chromospheres of late G and K supergiants|
The radiative transfer problem in non-LTE moving atmospheres has beenexplicitly solved for H-alpha line profiles. These computations havebeen done for a schematic model of the line-forming region over a widerange of optical depths and velocity gradients in order to cover theobserved characteristics in 23 G and K supergiants. The best theoreticalfits yield optical depths in the range 10-500 and velocity fields in therange 0.5-3 Doppler widths. The computed mass-flow rates lie in therange of 10 to the -5th to 10 to the -7th solar masses/yr; the higherthe extent of the line-forming region, the lower the mass-loss rates.The effect of the extent on the H-alpha emission components has alsobeen investigated in some detail.
|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.
|New UBVRI photometry for 900 supergiants|
A description is presented of the results obtained in connection with asystematic program of supergiant photometry on the Johnson UBVRI system.During the eight years after the start of the program, almost 1000 starshave been observed, about 400 three or more times each. The originalselection of stars used the spectral type catalog of Jaschek et al.(1964) to choose supergiants. Since observations were possible from bothChile and Canada, no declination limits were imposed, and no particularselection criteria were imposed other than to eliminate carbon stars.These are so red as to require enormous extrapolations of thetransformation equations.
|DDO Observations of Southern Stars|
|Photometric standard stars for the UBV and (RI)KC systems.|
|Polarization measurements of 313 nearby stars|
The linear polarization of 313 low galactic latitude stars has beenmeasured. With few exceptions all program stars have a spectral typelater than B9 and are within 600 parsec of the sun. 181 stars aresituated at the southern sky and 132 at the northern sky.
|VRI Photometry of E and F Region Stars [errata: 1978MNSSA..37...35C & 1980MNSSA..39...32C]|
|Lithium abundance in stellar atmospheres|
Data on the lithium abundance in the atmospheres of 491 stars arecompiled and reduced to a single system. The lithium abundances of thesestars are shown to differ by more than a factor of 1 million, and thedependence of lithium abundance on spectral type is determined forvarious groups of stars. It is found that cooler stars have lowerlithium abundances than hotter stars and that young stars have higherabundances than old stars. Data on the Li-6/Li-7 isotope ratio in theatmospheres of 30 stars are presented which indicate that Li-6 is notobserved in most cases and that the exceptions comprise magneticvariable stars with Li-6/Li-7 ratios of 0.10 to 2.00. It is concludedthat the observational results as a whole are satisfactorily explainedby the hypothesis that the same high lithium abundance characterized allstars at birth but then decreased in the course of evolution due tointermixing of matter.
|Five-channel photometry of cepheids and supergiants in the southern Milky Way.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...24..413P&db_key=AST
|Investigation of a Milky Way field in Canis Major|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79.1022C&db_key=AST
|Lithium in K-supergiants.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973MNRAS.163..337W&db_key=AST
|UBV and Hbeta photometry of the galactic cluster NGC 2343|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..868C&db_key=AST
|The space distribution and kinematics of supergiants|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..602H&db_key=AST
|UBV photometry of star clusters in the Magellanic Clouds.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..569V&db_key=AST
|Standard magnitudes in the E regions.|
|Summary of the parallaxes of 130 stars.|