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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Adaptive Optics Near-Infrared Spectroscopy of the Sagittarius A* Cluster
We present K-band λ/Δλ~2600 spectroscopy of fivestars (K~14-16 mag) within 0.5" of Sgr A*, the radio source associatedwith the compact massive object suspected to be a2.6×106Msolar black hole at the center ofour Galaxy. High spatial resolution of ~0.09" and good Strehl ratios of~0.2 achieved with adaptive optics on the 10 m Keck telescope make itpossible to measure moderate-resolution spectra of these starsindividually for the first time. Two stars (S0-17 and S0-18) areidentified as late-type stars by the detection of CO band headabsorption in their spectra. Their absolute K magnitudes and CO bandhead absorption strengths are consistent with early K giants. Threestars (S0-1, S0-2, and S0-16) with rproj<0.0075 pc (~0.2")from Sgr A* lack CO band head absorption, confirming the results ofearlier lower spectral and lower spatial resolution observations thatthe majority of the stars in the Sgr A* cluster are early-type stars.The absolute K magnitudes of the early-type stars suggest that they arelate O, early B main-sequence stars of ages less than 20 Myr. Thepresence of young stars in the Sgr A* cluster so close to the centralsupermassive black hole poses the intriguing problem of how these starscould have formed or could have been brought within its strong tidalfield.
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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
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On the Variability of Late B III-V Stars
We investigate the Hipparcos Satellite photometry of luminosity classIII-V B6-B9 stars. Most are relatively non-variable. Candidates forwhich further study is desirable are identified.
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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The ROSAT all-sky survey catalogue of optically bright OB-type stars.
For the detailed statistical analysis of the X-ray emission of hot starswe selected all stars of spectral type O and B listed in the Yale BrightStar Catalogue and searched for them in the ROSAT All-Sky Survey. Inthis paper we describe the selection and preparation of the data andpresent a compilation of the derived X-ray data for a complete sample ofbright OB stars.
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The structure of the interstellar gas towards stars in the globular cluster M 10.
Observations are presented of high resolution interstellar Na D and K I(λ7699 A) line profiles towards 3 stars in the globular cluster M10 and 2 field stars within 5deg of the cluster. The gas which isobserved towards all the programme stars is dominated by a strongcomponent at a velocity =~-0.7km/s; the bulk of this gas is shown to lieat a distance <~360 pc. Comparison is made with gas properties foradjacent high-latitude molecular clouds (Penprase 1993). Thelow-velocity gas apparently extends to distances well beyond themolecular clouds in this direction; there is, however, no evidence foradditional gas components in the region between the nearby gas and thedistant cluster. These observations extend our survey of the large-scalestructure of the nearby gas in the general direction l=~10+/-5degfurther into the northern Galactic hemisphere and we review the gascolumn density and velocity structure over the latitude range -25deg to+25deg.
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Optical and UV spectroscopy of stars in the direction of the Riegel & Crutcher cold cloud
Optical and UV spectral data are presented for the stars HD 165202,168708 which lie in the direction of the Riegel & Crutcher coldcloud. These observations complement our earlier studies in whichhigh-resolution HI profiles mapped the cold cloud in self-absorption(Montgomery et al.). HD 165202 lies in a direction close to where weobserve a maximum HI self-absorption column density and HD 168708 liestowards the edge of the cold cloud; from their spectra we determine thestellar distances to be ~=200 and 430 pc, respectively. We show that theHI column densities associated with the cold core represent some 3-10per cent of the total HI gas column observed towards the two stars. Wesuggest that the cloud core is embedded in diffuse, cold HI gas and thatthe sightlines contain a warm, intercloud medium; the gas observed inCH^+ may be produced in a thin interface between molecular gas of thecold cloud and the warm medium. Whilst it is not possible to obtain adetailed description of these sightlines, the evidence points to arelatively dense cloud core of space density ~=100-200 cm^-3 andthickness <=1 pc.
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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.
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SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
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The local distribution of NA I interstellar gas
We present high-resolution absorption measurements (lambda/Delta lambdaapproximately 75,000) of the interstellar Na I D lines at 5890 A toward80 southern hemisphere early-type stars located in the localinterstellar medium (LISM). Combining these results with other sodiummeasurements taken from the literature, we produce galactic maps of thedistribution of neutral sodium column density for a total of 293 starsgenerally lying within approximately 250 pc of the Sun. These mapsreveal the approximate shape of the mid-plane contours of the rarefiedregion of interstellar space termed the Local Bubble. Its shape is seenas highly asymmetric, with a radius ranging from 30 to 300 pc, and withan average radius of 60 pc. Similar plots of the Galactic mid-planedistribution of sources emitting extreme ultraviolet radiation show thatthey also trace out similar contours of the Local Bubble derived from NaI absorption measurements. We conclude that the Local Bubble absorptioninterface can be represented by a hydrogen column density,NuETA = 2 x 1019 cm-2, which explainsboth the local distribution of Na I absorption and the observed galacticdistribution of extreme ultraviolet sources. The derived mid-planecontours of the Bubble generally reproduce the large-scale featurescarved out in the interstellar medium by several nearby galactic shellstructures.
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Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
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UBV photometry of HD stars in the fields of selected cataclysmic variables.
Not Available
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High Resolution Spectroscopic Observations of Ty-Coronae
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&A...274..785L&db_key=AST
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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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The nearby interstellar material in the general direction towards M22
High-resolution optical spectra of interstellar absorption lines areused to examine reddening variations across the globular cluster M22which are produced by the nearby low-velocity gas. Fifteen cluster starstogether with three stars within 1.3 deg of the cluster were observed inthe Na D lines and in some case also the K I (7699 A) line. Optical andultraviolet spectra of closer stars which lie within several degrees ofM22 confirm that a rapid increase in gas-column density occurs at adistance of approximately 100 pc, but the material is considerably moreextensive in thickness than has been suggested previously. Although thecurrent schematic models for the Loop I and local bubbles describe in ageneral way some of the observed features of this local interstellarmaterial, they cannot account directly for the properties and thicknessof the gas determined in the present study.
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Further thoughts on the interstellar spectrum of HD 174632
High-resolution observations (3.6 km/s FWHM) of interstellar Ca IItoward the star HD 174632 are presented. This spectrum complements theNa I spectrum presented in a previous paper (Crawford 1988), and enablesadditional conclusions to be drawn as to the origin of the observedabsorption components. Of the three components observed in both Ca IIand Na I, that at -4.3 km/s is now attributed to diffuse gas associatedwith the R CrA dark cloud, and that at -22 km/s is interpreted asarising in the local interstellar medium; the origin of the component at-18 km/s is unclear, but it appears to exist beyond the localinterstellar bubble and has a Na I/Ca II ratio suggestive of an originin relatively dense gas.
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Further high-resolution NA I observations of the local interstellar medium
High-resolution absorption measurements of the interstellar Na I D linesat 5890 A observed toward 27 early-type stars in the local interstellarmedium (LISM) are presented. These results are combined with otherhigh-resolution sodium measurements to map the space distribution ofneutral sodium column density for some 118 stars out to less than 200pc. These measurements indicate an upper limit to the neutral sodiumcolumn density of log N(Na I) less than 10.0/sq cm can be inferred outto a distance of 50 pc in most directions in the LISM. Also, therarefield region of the Local Bubble may extend beyond 60 pc in at least35 percent of the directions sampled thus far. Evidence is shown for aubiquitous, comoving vector for neutral NaI gas clouds in the LISM whichis in a different direction to LISM vectors previously reported for moreionized local gas clouds. A comparison of the measured sodium columnswith those of interstellar Ca II for a sample of 12 stars within 95 pcresults in a ratio of Na I/Ca II less than 0.5 for most stars. Thisvalue implies that there could be warm, neutral gas with T of about12,500 K beyond 50 pc in the LISM.
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High-resolution observations of interstellar NA I towards HD 174632
High-resolution observations of interstellar Na I towards the relativelynearby (180 pc) and lightly reddened, E(B-V) = 0.12, B8V star HD 174632are presented. There are two distinct interstellar cloud components inthis line-of-sight, with heliocentric velocities of about -4.4 and-17.6km/s. A third, much weaker, component at about -21.7 km/s also appearsto be present. Na I column densities for these components have beenobtained by line-profile fitting, and estimates have been made of theN(Na I)/N(H) ratios. These are found to be consistent with standarddiffuse interstellar clouds. Arguments are presented that these cloudsare associated with the boundary between the local low-densityinterstellar bubble and the neighboring Loop I bubble, at a distancebetween about 50 and 100 pc from the Sun.
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The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
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The S201 far-ultraviolet imaging survey. III - A field in Sagittarius
Far-ultraviolet imagery of a 20 deg diameter field in Sagittarius,centered near (1950) R.A. 18 h 34 m, decl. -30 deg 25 arcmin, wasobtained by the S201 far-ultraviolet camera during the Apollo 16mission. In a 10-minute exposure covering the 1250-1600 A wavelengthrange, 1034 star images are detectable, with a limiting ultravioletmagnitude of about 10. Most of these objects are identified withearly-type stars listed in the Smithsonian Astrophysical ObservatoryStar Catalog, the Catalog of Stellar Identifications, or both, but 203objects remain unidentified or are identified with late-type stars. Thephotometric measurements appear to be in reasonable agreement with thoseof the International Ultraviolet Explorer for stars in common, and withexpectations for A0 stars. A detailed photometric study was made of theMessier 8 region, and it is concluded that dust-scattered starlightcontributes about half of the total radiation observed from the centralregion of M8.
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UBV photometry for southern OB stars
New UBV photometry of 1227 OB stars in the southern Milky Way ispresented. For 1113 of these stars, MK spectral types have been reportedpreviously in a comprehensive survey to B = 10.0 mag.
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Is star formation bimodal ? II. The nearest early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..187E&db_key=AST
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INHABITED SKY
