A catalogue of eclipsing variables
A new catalogue of 6330 eclipsing variable stars is presented. Thecatalogue was developed from the General Catalogue of Variable Stars(GCVS) and its textual remarks by including recently publishedinformation about classification of 843 systems and making correspondingcorrections of GCVS data. The catalogue1 represents thelargest list of eclipsing binaries classified from observations.
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Chandra X-Ray Observations of Young Clusters. I. NGC 2264 Data
We present results of a Chandra observation of a field in NGC 2264. Theobservations were taken with the ACIS-I camera with an exposure time of48.1 ks. We present a catalog of 263 sources, which includes X-rayluminosity, optical and infrared photometry, and X-ray variabilityinformation. We found 41 variable sources, 14 of which have a flarelikelight curve, and two of which have a pattern of a steady increase ordecrease over a 10 hr period. The optical and infrared photometry forthe stars identified as X-ray sources are consistent with most of theseobjects being pre-main-sequence stars with ages younger than 3 Myr.
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A spectroscopic survey for lambda Bootis stars. II. The observational data
lambda Bootis stars comprise only a small number of all A-type stars andare characterized as nonmagnetic, Population i, late B to early F-typedwarfs which show significant underabundances of metals whereas thelight elements (C, N, O and S) are almost normal abundant compared tothe Sun. In the second paper on a spectroscopic survey for lambda Bootisstars, we present the spectral classifications of all program starsobserved. These stars were selected on the basis of their Strömgrenuvbybeta colors as lambda Bootis candidates. In total, 708 objects insix open clusters, the Orion OB1 association and the Galactic field wereclassified. In addition, 9 serendipity non-candidates in the vicinity ofour program stars as well as 15 Guide Star Catalogue stars were observedresulting in a total of 732 classified stars. The 15 objects from theGuide Star Catalogue are part of a program for the classification ofapparent variable stars from the Fine Guidance Sensors of the HubbleSpace Telescope. A grid of 105 MK standard as well as ``pathological''stars guarantees a precise classification. A comparison of our spectralclassification with the extensive work of Abt & Morrell(\cite{Abt95}) shows no significant differences. The derived types are0.23 +/- 0.09 (rms error per measurement) subclasses later and 0.30 +/-0.08 luminosity classes more luminous than those of Abt & Morrell(\cite{Abt95}) based on a sample of 160 objects in common. The estimatederrors of the means are +/- 0.1 subclasses. The characteristics of oursample are discussed in respect to the distribution on the sky, apparentvisual magnitudes and Strömgren uvbybeta colors. Based onobservations from the Observatoire de Haute-Provence, OsservatorioAstronomico di Padova-Asiago, Observatório do Pico dosDias-LNA/CNPq/MCT, Chews Ridge Observatory (MIRA) and University ofToronto Southern Observatory (Las Campanas).
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UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
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Incidence of X-ray sources among magnetic chemically peculiar stars
Cash & Snow (1982) and Golub et al. (1983) have detected X-rayemission from 3 out of 7 observed magnetic chemically peculiar (CP)stars. Although the incidence of X-ray sources apparently is very high,these authors concluded that such emission is not unquestionable becauseof the presence of a companion. To determine the incidence of X-raysources among hot CP stars, I have checked the list of B-type starsmeasured by Grillo et al. (1992) selecting 90 stars. Of the 4 magneticCP stars showing X-ray emission 3 are members of a binary system. Thusit appears that detectable X-ray emission from magnetic CP stars is notvery common and still questionable. To find out whether HD 37017presents X-ray emission (Drake et al. 1987) or not (Grillo et al. 1992),I have analyzed an HRI frame from the ROSAT satellite finding noevidence for X-ray emission at this star's position.
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Liste des étoiles Ap et Am dans les amas ouverts (édition révisée)
Not Available
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An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
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More radial-velocity measurements in young open clusters
Further high resolution radial-velocity measurements are reported in 23young open clusters using the Kitt Peak CCD coude spectrograph on the0.9-m feed telescope. The radial velocities for the cluster stars arederived with the technique of cross correlation. The internal precisionof the velocity measurements is typically 2 km/s for early type stars.From these new data and previously published velocities, the observedstars in two clusters, NGC 663 and NGC 2287, were found to show arelatively small dispersion in the measured mean velocities. Furtherobservations of stars in young clusters will be useful in helping toestablish an early-type-star-velocity standard system.
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VBLUW photometry of the very young open cluster NGC 2264
This study presents and discusses VBLUW photometry of 112 stars with Vless than 13 in the area of the very young cluster NGC 2264.Temperatures, gravities, and reddening for stars hotter than 8400 K aredetermined. The reddening and the distance are found to be in goodagreement with the results of other references; to the existing list ofpresumable nonmembers, six stars are tentatively added as possiblenonmembers.
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Remarks to Lapicz positions of stars in NGC 2264.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990RMxAA..20..113L&db_key=AST
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Close binaries observed polarimetrically
Not Available
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Liste des étoiles Ap et Am dans les amas ouverts (Edition révisée)
Not Available
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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.
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UVBY beta photometry of stars in the field of NGC 2244 and NGC 2264
Results are presented from uvby beta photometric observations of 34stars in the fields of NGC 2244 and NGC 2264. Photometric andastrometric indicators suggest that about a third of the sample arenonmembers of the clusters. Cluster color excesses are determined forthe two clusters. For the stars examined, log g and effectivetemperature are estimated. Also, stellar radii, masses, and positions inthe H-R diagram are calculated. The cluster ages and the main-sequencelifetime for massive stars show that star formation in the region hasnot been restricted to a single epoch.
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The 69th Name-List of Variable Stars
Not Available
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Chemically peculiar stars in open clusters. I - The catalog
The largest existing compilation is presented of Ap and Am open clusterstars. The catalog contains information on 381 chemically peculiar (CP)stars of the upper main sequence in 79 open clusters. The catalog iscomposed of the following tables: (1) the main body, which lists CP (orsuspected CP) stars which are kinematical (or suspected kinematical)members of open clusters; (2) the list of CP (or suspected CP) starssometimes numbered among cluster members but which are actuallykinematical nonmembers; (3) the list of stars sometimes designated as'peculiar' but, in fact, probably not CP; (4) references for numberingsystems of cluster stars; (5) references for membership; and (6)references for spectral and/or peculiarity types.
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Catalog of AP and AM stars in open clusters
The previous results of Raab (1922), Markarian (1951), and Collinder(1931) have been used to catalog Ap and Am stars that are in the fieldof open clusters. Tabular data are presented for the clusterdesignation, the HD or HDE number, the right ascension (1900), thedeclination (1900), and the magnitude. Also listed are the spectraltypes and, for certain stars, the probability of cluster membership.
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Equatorial coordinates of double and multiple star components measured on GPO astrographic plates
Equatorial coordinates are given for some of the multiple starcomponents having incomplete or inconsistent information in the IndexCatalog of Visual Double Stars. Two photographic plates were taken foreach system with incomplete or inconsistent information using the GPOastrograph. The plate measurement and reduction techniques used aredescribed.
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On the distances to the young open clusters NGC 2244 and NGC 2264
A new determination of the distances of the young open clusters NGC 2244and NGC 2264 is presented. It is based on distance moduli for individualOB-type stars in which the influence of the anomalous ratio of total toselective extinction, if any, is taken into account. A discussion isincluded, first, of the accuracy of the color-difference method comparedto that of other current methods for determining R and, second, of theerrors in the determination of the distances for clusters embedded innonuniform H II regions. New photoelectric measurements (UBVRI andJHKLM), and new spectrophotometric data (IDS spectra) are presented forOB-type stars in these clusters as well as summaries of publishedphotometric data. The locations in the H-R diagram of the program starsseem to suggest that these massive stars are on the main sequence,supporting the idea of continuous star formation.
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HD 47755, a new eclipsing binary
The IUE spectra of the close binary star HD 47755 have been examined inorder to determine its geometry, chemical composition, and light curve.UBV fluxes in the spectra, when dereddened for E(B-V) = 0.09 yield aneffective temperature of 16,500 K. The ratio of the mean radii of thestars is found to agree well with an old blueband spectrophotometricvalue. Eclipses in the binary have been observed and a complex greenlight curve is derived. It is suggested that the wind from at least oneof the components of HD 47755 is the source of the complexity in thelight curve. The geometry of the HD 47755 is compared to that of V 641Mon, A definite cluster member of NGC 2264. The interstellar linespectrum is found to be similar to that of V 641 Mon and the columndensities for a few interstellar ions are given in a table. Evaluationof the nonastrometric evidence indicates that HD 47755 is also a memberof NGC 2264.
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EXOSAT observations of active stellar coronae in the Cygnus Loop, T Tau and NGC 2264 regions
A highly variable point X-ray source, first seen by the Einstein IPC,has been positioned with the Exosat CMA and identified with a bright (V= 8.5) K0 star. Although in the direction of the southern half of theCygnus Loop, this star is almost certainly a foreground object andtypical of other active cool stars that are related to RS CVn systems.An Exosat program to study T Tauri stars failed to detect T Tau itself.However, a strong X-ray source was observed 15 arcmin from T Tau, whichin its turn had not been seen by Einstein. This new source has beenidentified with a hitherto unstudied 13 mag star which is likely to be adMe flare star. The young star cluster NGC 2264 was observed with theExosat CMA in an attempt to identify the sources found during anEinstein IPC study of S Mon. Apart from S Mon itself, only UV-brightobjects were seen, but several of these are considered likelycounterparts of the Einstein sources.
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Catalog of BV magnitudes and spectral classes of 6000 stars
The present catalog, compiled at the Abastumani Observatory, contains BVmagnitudes and spectral classes of about 6000 stars up to V(lim) = 13.0min five circular areas of 18 sq deg located near the salactic-equatorplane. The catalog is intended for star-statistics studies ofstar-formation regions.
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IUE spectroscopy, visible-band photometry, and polarimetry of HD 47732 (V641 Monocerotis)
Several high- and low-dispersion IUE spectra are described for the hot,massive close binary HD 47732. The stellar silicon lines do not showtheoretically expected strength, the weakness being attributed toincipicent emission. A weak stellar wind is measurable with an expansionvelocity of about 500 km/s. There is difficulty in fitting a modelatmosphere to all of the IUE continuum and visible band and IR measures.These difficulties are resolved by appealing to a 22,500 K modelatmosphere and a distinctive interstellar extinction law. Numerous Vband measures show the polarization to be variable, but not strongly ina phased-locked way. This suggests sporadic outbursts of gas feeding theshell. Several seasonal V band light curves are discussed, and theseasonal variations among them are attributed to variable developmentsof a systemic shell which scatters the photospheric light and dilutes toa variable degree the light variation due to ellipticity of figure ofthe component stars.
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IUE low-dispersion reference atlas
This atlas, published by ESA and essentially devoted to normal stars,presents 229 graphic spectra together with the corresponding fluxes andan ultraviolet spectral type. The preparation of this publicationconfirmed that MK classifications cannot simply be transferred to theultraviolet range. A set of transparencies illustrates the referencesequences constructed from the ultraviolet data. A magnetic-tape copy ofall the spectra pertaining to this atlas is available from the StellarData Center in Strasbourg.
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Positions of stars in NGC 2264
Positions in the region of NGC 2264, obtained using the Lick CarnegieAstrograph are presented. The methods used to obtain the positions arebriefly discussed.
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IUE low-dispersion spectra flux catalogue. I - Normal stars (magnetic tape)
A magnetic tape catalog of the fluxes (2A-step) of 229 selectedlow-dispersion stellar spectra prepared by the Centre de Calcul deStrasbourg-Cronenbourg is presented in the form of a set of tables. Thecatalog uses the general MK frame and centers on stars exhibiting normalbehavior in the ultraviolet. All the stars included in the catalog arelisted together with their MK and UV spectral classifications. Thespectra were collected by the International Ultraviolet Explorer (IUE)with the aim of establishing reference spectral sequences in theultraviolet range.
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Photometric properties of AP stars in the Geneva system
An examination of the properties in some photometric diagrams of morethan 600 Ap stars measured in the Geneva photometric system confirm thatthe Balmer discontinuity is smaller than for normal stars, along withthe link between a proposed peculiarity parameter and both rotationalvelocity and effective magnetic field. It is shown that the peculiarityparameter is sensitive to interstellar reddening, and it is foundthrough examination of the standard deviations for visual magnitudesthat cool CP 2 stars without Eu peculiarity have the greatestamplitudes. Rapid rotators have a mild peculiarity, while positivecorrelation exists for Si and SrCr stars.
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Near-infrared observations of trapezium-type multiple systems Catalogue of observations and a new determination of the reddening law
Results are presented from a large scale near-infrared survey of smallsky areas of the Milky Way containing trapezium-type multiple starsystems located within young galactic clusters, H II regions or darknebulosities. Photometric maps at wavelength 2.2 microns complemented bybroadband JHKL photometry of the majority of the sources detected and ofthe star members of the systems were obtained. A number of randomlychosen comparison regions along the galactic plane were also mapped andthe results were also used, with recent semi-empirical models, todetermine the number of field stars expected for the program surveys.Analyses of the infrared two-color diagrams provide determinations ofthe values of the color excess ratios E(J-H)/E(H-K), E(H-K)/E(K-L) andE(J-K)/E(K-L). The resulting reddening law is found to differsignificantly from that in the direction of the Ophiuchus and Taurusdark clouds and possibly towards the Galactic Center.
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