|Binary Star Orbits. II. Preliminary First Orbits for 117 Systems|
Orbital elements are presented for 117 binary systems with no previousorbit calculation. For nearly all of these systems, these elements mustbe regarded as preliminary, but the ephemerides presented here should berelatively accurate over the next several decades. Further, the analysisof these systems should highlight the need for their continuedobservation by dedicated programs to improve the veracity of theseelements.
|Two-colour photometry for 9473 components of close Hipparcos double and multiple stars|
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
|A Second Catalog of Orbiting Astronomical Observatory 2 Filter Photometry: Ultraviolet Photometry of 614 Stars|
Ultraviolet photometry from the Wisconsin Experiment Package on theOrbiting Astronomical Observatory 2 (OAO 2) is presented for 614 stars.Previously unpublished magnitudes from 12 filter bandpasses withwavelengths ranging from 1330 to 4250 Å have been placed on thewhite dwarf model atmosphere absolute flux scale. The fluxes wereconverted to magnitudes using V=0 for F(V)=3.46x10^-9 ergs cm^-2 s^-1Å^-1, or m_lambda=-2.5logF_lambda-21.15. This second catalogeffectively doubles the amount of OAO 2 photometry available in theliterature and includes many objects too bright to be observed withmodern space observatories.
|The Stellar Extreme-Ultraviolet Radiation Field|
The local extreme ultraviolet (EUV) radiation field from stellar sourceshas been determined by combining the EUV spectra of 54 stars, taken withthe spectrometers aboard the Extreme Ultraviolet Explorer satellite. Theresultant spectrum over the range 70-730 A is estimated to be 95%complete above 400 A and 90% complete above 200 A. The flux contributedby two B stars and three hot white dwarfs dominate the spectrum exceptat the shortest wavelengths, where an assortment of EUV source typescontribute. The high electron densities measured toward nearby stars canbe accounted for by photoionization from this radiation field, but thespectrum is too soft to explain the overionization of helium withrespect to hydrogen recently measure in the Local Cloud.
|The Extreme Ultraviolet Explorer Stellar Spectral Atlas|
We present an atlas of extreme ultraviolet (EUV) spectra of 95 brightstellar sources observed between 1992 July and 1996 June with theExtreme Ultraviolet Explorer (EUVE) spectrometers. These data are takenin the short- (SW; 70-190 Angstroms), medium- (MW; 140-380 Angstroms),and long-wavelength bandpasses (LW; 280-760 Angstroms) at roughly 0.5,1, and 2 Angstroms resolution, respectively. We describe thespectrometers and detail the procedure used to reduce the observationaldata to spectra. The atlas is grouped by the type of source: O-A stars,F-M stars, white dwarfs, and cataclysmic variables. We present a briefoverview of the general nature and EUV spectral distribution of eachgroup and present accompanying notes and individual spectra for eachsource. We show selected F-M sources in more detail with identificationsof the brightest spectral lines illustrating the characteristics of theEUV spectra of stars of various temperatures. The current study is themost complete compilation to date of aggregate spectra of bright EUVstellar sources.
|DDO photometry of E-region stars and equatorial standards - II|
This paper deals with the observations of 72 of McClure's equatorialstandard stars, made with the same photometer and DDO filters as wereused for the E-region stars in Cousins' Paper I in order to standardizethe observations. These observations were reduced in the natural systemand later transformed into McClure's system. Zero-point ties between theequatorial and E-region stars were also needed to standardize the lattersystem. With the exception of C(38-41), our photometry agrees as wellwith McClure's standard system as his own observations do, but both showsome small, apparently systematic, differences which are almostinevitable with a system like the DDO unless the response functions arevery well matched. Comparisons with 17 of Dean's measurements ofE-region stars show good agreement (~2 mmag) for the averagedzero-points, but there are small colour differences affecting C(35-38)and C(38-41) because of differences between the filters and thereduction procedures. This paper also deals with several problems in theDDO photometry that have implications for precision photometry ingeneral.
|The Second Extreme-Ultraviolet Explorer Source Catalog|
We present the second catalog of extreme-ultraviolet objects detected bythe Extreme-Ultraviolet Explorer. The data include (1) all-sky surveydetections from the initial 6 month scanner-survey phase, (2) additionalscanner detections made subsequently during specially programmedobservations designed to fill in low-exposure sky areas of the initialsurvey, (3) sources detected with deep-survey-telescope observationsalong the ecliptic, (4) objects detected by the scanner telescopesduring targeted spectroscopy observations, and ( 3) other observations.We adopt an innovative source detection method that separates the usuallikelihood function into two parts: an intensity diagnostic and aprofile diagnostic. These diagnostics allow each candidate detection tobe tested separately for both signal-to-noise ratio and conformance withthe known instrumental point-spread function. We discuss the dependenceof the false-alarm rate and the survey's completeness on the survey'ssensitivity threshold. We provide three lists of the EUV sourcesdetected: the all-sky survey detections, the deep-survey detections, andsources detected during other phases of the mission. Each list givespositions and intensities in each wave band. The total number of objectslisted is 734. For approximately 65% of these we also provide plausibleoptical, UV, radio, and/or X-ray identifications.
|Hot White Dwarfs in the Extreme Ultraviolet Explorer Survey. I. Properties of a Southern Hemisphere Sample|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...467..782V&db_key=AST
|ICCD Speckle Observations of Binary Stars. XIII. Measurements During 1989- 1994 From the Cerro Tololo 4 M Telescope|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....111..936H&db_key=AST
|The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources - II. The 2RE Source Catalogue|
During 1990-1991 the Wide Field Camera (WFC) on the ROSAT satelliteperformed the first all-sky survey at EUV wavelengths. The survey wasconducted in two `colours' using broad-band filters to define wavebandscovering the ranges 60-140 A and 112-200 A. It was fully imaging, witheffective spatial resolution of about 3 arcmin FWHM, and point sourcelocation accuracy of typically better than 1 arcmin. From an initialanalysis, Pounds et al. published the WFC Bright Source Catalogue (BSC)of 383 sources. In this paper we report results from reprocessing of thecomplete survey database; the resulting list of sources is the `2RE'Catalogue. It contains 479 sources, of which 387 are detected in bothsurvey wavebands, a significant advance on the BSC (80 per cent versus60 per cent). Improvements over the original BSC include: (i) betterrejection of poor aspect periods, and smaller random errors in theaspect reconstruction; (ii) improved background screening; (iii)improved methods for source detection; (iv) inclusion of atime-variability test for each source; (v) more extensive investigationof the survey sensitivity. We define the catalogue selection criteria,and present the catalogue contents in terms of tables and sky maps. Wealso discuss the sky coverage, source number-flux relations, opticalidentifications and source variability.
|A comparison of the ROSAT WFC and EUVE source catalogues|
The first all-sky surveys at extreme-ultraviolet (EUV) wavelengths haverecently been carried out by the ROSAT Wide Field Camera (WFC,1990-1991) and the EUV Explorer (EUVE, 1992-1993). We present acomparison of the WFC and EUVE all-sky survey results, concentrating onthe correspondence between the two pairs of short-wavelength filters,operating in the band from ~60 to ~200 A. Over 80 per cent of the EUVE100-A sources are detected by the WFC, whereas for the EUVE 200-Asources the fraction is as high as 93 per cent. Both surveys aredominated by late-type (F-M) stars and hot white dwarf stars, withcataclysmic variables (CVs), early-type stars and active galactic nucleialso contributing. We use the effective area versus wavelengthcalibrations of the various filters to predict count-rate ratios forvarious model spectra. By comparing these predictions with the measuredratios, we are able to define the range of spectral properties typicalof the various classes of EUV source. The level of flux variability inthe EUV band of late-type stars and CVs is also investigated.
|The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..135A&db_key=AST
|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 first Extreme Ultraviolet Explorer source catalog|
The Extreme Ultraviolet Explorer (EUVE) has conducted an all-sky surveyto locate and identify point sources of emission in four extremeultraviolet wavelength bands centered at approximately 100, 200, 400,and 600 A. A companion deep survey of a strip along half the eclipticplane was simultaneously conducted. In this catalog we report thesources found in these surveys using rigorously defined criteriauniformly applied to the data set. These are the first surveys to bemade in the three longer wavelength bands, and a substantial number ofsources were detected in these bands. We present a number of statisticaldiagnostics of the surveys, including their source counts, theirsensitivites, and their positional error distributions. We provide aseparate list of those sources reported in the EUVE Bright Source Listwhich did not meet our criteria for inclusion in our primary list. Wealso provide improved count rate and position estimates for a majorityof these sources based on the improved methodology used in this paper.In total, this catalog lists a total of 410 point sources, of which 372have plausible optical ultraviolet, or X-ray identifications, which arealso listed.
|DDO photometry of E-region stars and equatorial standards (paper I).|
|Secondary UVBY standards in the Harvard E-regions|
Photoelectric uvby photometry for 201 stars which are already UBV (RI)cstandards is presented. The photoelectric data are closely tied to theCousins uvby standards and the stars should be suitable for use asfainter (7-11 mag) secondary standards.
|A homogeneous catalog of new UBV and H-beta photometry of B- and A-type stars in and around the Scorpius-Centaurus OB association|
B- and A-type stars in and near the Sco-Cen OB association areinvestigated with UBV and H-beta photometry to acquire data relevant tothe luminosity function of Sco-Cen. The measurements generally consistof two 10-s integrations of U, B, V, (W, N) filters, and theobservations are corrected iteratively for atmospheric extinction andinstrumental response. The data presented give the mean V magnitude,mean B-V, mean U-B, and the estimated uncertainties for these values.The catalog provides a homogeneous catalog of data for a large fieldwith stellar objects delineating membership to the association Sco-Cenand that affect the luminosity function of the aggregate.
|Secondary standards for H-beta photometry in the Southern Hemisphere (second series).|
|Southern JHKL standards|
The basis for the current SAAO standard photometric system at JHKL isgiven. This depends on an extensive investigation involving 230 starsdistributed around the sky. The accuracy is estimated at + or - 0.02 magfor J, H and K and + or - 0.05 mag for L.
|Secondary standards for H-beta photometry in the E regions.|
|UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.|
|Secondary standards for the Stromgren UVBY system|
Observations of 158 E region stars have been made in the Stromgrensystem, using the 46-cm reflector at Cape Town. They are mostly brighterthan eighth magnitude and are intended for use as secondary standardsfor the four-color system. The E region relative zero points are definedwith a precision of + or - 0.001 mag, and the internal standard errorsof the colors life between + or - 0.001 and + or - 0.002 mag.
|The Sirius supercluster|
Photometric data on the chemical composition of 927 A stars in the UrsaMajor stream, called the Sirius supercluster, were used to estimate theage and place of formation of the objects. The stars studied are in thesolar neighborhood and have been observed to be co-moving in a velocityellipsoid with a (U, V) velocity of 10.3 km/sec and concentrated in aspatial volume less than 10 pc across. The Stromgren and Geneva systemphotometric data show that the supercluster is homogeneous in chemicalcontent, although the value of the forbidden Fe/H ratio could not beprecisely determined. The supercluster age is projected to be from260-620 Myr, with the origin having been in the Carina spiral arm of theGalaxy.
|UBV photometry of E region standard stars of intermediate brightness|
Photometry data are given for 335 stars in the nine E regions.Observations were made using a photometer and filters on the 47 cmreflector at Cape Town. The stellar dispersions are summarized. Data arepresented in tabular form.
|Micrometric measurements of southern double stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983A&AS...53..177A&db_key=AST
|Photometric boxes in the four-color system|
Photometric boxes derived from the latest four-color catalogue compiledby Hauck and Mermilliod (1980) containing uvby and H-beta observationsfor more than 15,000 stars are discussed. The construction andpopulation of stellar boxes, the distribution of boxes with spectraltype, the relations between a geneva box and a four-color box, and theuse of stellar boxes for photometric classification are considered. Itis concluded that the method of stellar boxes is a very useful tool inphotometric investigation.
|Measures of Southern Double Stars in 1981|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982A&AS...50..115W&db_key=AST
|DDO Observations of Southern Stars|
|Photometric standard stars for the UBV and (RI)KC systems.|
|Fainter Standards for VRI Photometry in the E Regions|