|eta Carinae: The optical flare-like events during low-excitation passages|
The 1992.5 and 1998.0 low-excitation events of the possible binary inthe core of eta Carinae show a conspicuous flare-like event in opticaland near-ultraviolet light. These events last a couple of months andhave a light amplitude of 0.1m-0.2m in V. Considering the presence of adense (bi-polar) stellar wind, one explanation could be that some typeof a hot area is created by an increased mass flow from the S Dorprimary near the hypothetical periastron. These flare-like events areterminated by sharp dips. The magnitude differences between theunderlying light source and the central light (``Component A'') arederived. It turns out that they are fainter than Component A by ~ 2fm5. The luminosity could be of the order of 105Lsun. It was possible to derive two new continuum values inthe near-UV, reinforcing the impression derived from the HST fluxes thatComponent A has a very strong radiation peak in the Balmer continuum.This can probably be explained by the strong emission of the stellarwind.
|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
|Late-type members of young stellar kinematic groups - I. Single stars|
This is the first paper of a series aimed at studying the properties oflate-type members of young stellar kinematic groups. We concentrate ourstudy on classical young moving groups such as the Local Association(Pleiades moving group, 20-150Myr), IC 2391 supercluster (35Myr), UrsaMajor group (Sirius supercluster, 300Myr), and Hyades supercluster(600Myr), as well as on recently identified groups such as the Castormoving group (200Myr). In this paper we compile a preliminary list ofsingle late-type possible members of some of these young stellarkinematic groups. Stars are selected from previously established membersof stellar kinematic groups based on photometric and kinematicproperties as well as from candidates based on other criteria such astheir level of chromospheric activity, rotation rate and lithiumabundance. Precise measurements of proper motions and parallaxes takenfrom the Hipparcos Catalogue, as well as from the Tycho-2 Catalogue, andpublished radial velocity measurements are used to calculate theGalactic space motions (U, V, W) and to apply Eggen's kinematic criteriain order to determine the membership of the selected stars to thedifferent groups. Additional criteria using age-dating methods forlate-type stars will be applied in forthcoming papers of this series. Afurther study of the list of stars compiled here could lead to a betterunderstanding of the chromospheric activity and their age evolution, aswell as of the star formation history in the solar neighbourhood. Inaddition, these stars are also potential search targets for directimaging detection of substellar companions.
|Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics|
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (18.104.22.168) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
|On the Variability of Early K Stars|
We investigate the Hipparcos Satellite photometry of K0-K4 stars tostudy their pattern of activity. Most are not particularly variable. Afew stars for which further study is desirable are identified.
|The 74th Special Name-list of Variable Stars|
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
|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.
|The kinematics of young disk population supercluster members|
A discussion of the total space motions of early-type members of youngdisk population superclusters, derived from distances based on aphotometric calibration of four-color and H-beta photometry, shows anincrease in total velocity with increasing radial distance from the sun,within each supercluster. The rate of increase with distance varies fromsupercluster to supercluster because it results from the interaction oftwo effects - an 'expansion' that involves the total space motion and a'rotation' that involves only the V-velocity because it arises from therequirement that supercluster members have isoperiodic, galactic orbits.The ratio of the velocity in the direction of galactic rotation(V-velocity) to the total space motion determines the size of theresultant effect from the contradictory 'rotation' and 'expansion'terms. The expansion term is 40 to 45 km's/kpc in the superclustersdiscussed, whereas the rotation term is dV/dX = -(b-A) = 26 km/s/kpc,where B and A are the constants of galactic rotation.
|The IC 2391 supercluster|
Sixty-three field stars and the sparse cluster IC 2391 have beenidentified as members of the IC 2391 supercluster. The members have atleast 95 percent of their space motion, directed toward (A,D) = (5.82h,- 12.44d). Like members of the very similar Pleiades supercluster, theIC 2391 supercluster contains objects of two ages: t = 8 x 19 exp 7 and2.5 x 10 exp 8 yr. A prototype very active chromosphere star and theenigmatic giant variable TZ For are supercluster members together withtwo A-type stars suspected of possessing particulate disks. Anespecially interesting member is the system of Xi Cep (HR 8417) in whichthe two brightest components are greatly undermassive.
|Close binaries observed polarimetrically|
|Einstein Observatory magnitude-limited X-ray survey of late-type giant and supergiant stars|
Results are presented of an extensive X-ray survey of 380 giant andsupergiant stars of spectral types from F to M, carried out with theEinstein Observatory. It was found that the observed F giants orsubgiants (slightly evolved stars with a mass M less than about 2 solarmasses) are X-ray emitters at the same level of main-sequence stars ofsimilar spectral type. The G giants show a range of emissions more than3 orders of magnitude wide; some single G giants exist with X-rayluminosities comparable to RS CVn systems, while some nearby large Ggiants have upper limits on the X-ray emission below typical solarvalues. The K giants have an observed X-ray emission level significantlylower than F and F giants. None of the 29 M giants were detected, exceptfor one spectroscopic binary.
|Walraven photometry of nearby southern OB associations|
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
|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.
|Stellar chromospheres - H-alpha and CA II K profiles|
A set of medium to high-resolution observations of H-alpha and Ca II Klines in a sample of Population I stars is presented in order to examinethe systematics of H-alpha absorption profiles and to determineempirically the extent to which velocity fields observed therein arereflected in the chromospheric component of the Ca II line. Formain-sequence stars, bright Ca II K emission profiles accompany shallowH-alpha lines with sharp central cores, unlike the apparently U-shapedH-alpha cores of stars displaying relatively weak Ca II K emission. Forgiants and supergiants, the H-alpha line is generally wider than acomputed LTE photospheric profile, with significant K(3) absorptionpresent in the Ca II K(2) reversal profile. The excess widths appear tocorrelate with the strength of the K(3) absorption. Estimates of thestrength of Ca II K(3) indicate severe modifications of Ca II K(2)widths and intensities, strongly affecting the cooling role of Ca II Kin the upper chromospheres.
|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|
|Refined Data for Parallax Stars|
|Standard Stars for Hα Photometry|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...44..337S&db_key=AST
|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.
|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
|Luminosity and velocity distribution of high-luminosity red stars near the sun. I. The very young disk population|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973PASP...85..289E&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
|Narrow-Band and Broad-Band Photometry of Red Stars. III. Southern Giants|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...161..199E&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
|Stellar groups, VI. Space motions of the dwarf A-type and giant M-type stars in the solar neighbourhood|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.120..448E&db_key=AST
|The radial velocities of 185 stars observed at the Cape.|