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.
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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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Red and infrared colours of B stars and the reddening law in the Galaxy
The red and infrared intrinsic colours of B stars are derived fromphotometric observations through the UBV(RI)_CJHK and Hβ filters of257 early-type stars. Those stars for which the UBV and Hβmeasurements match the published spectral class, and which show no othersigns of peculiarity, are used to determine the intrinsic photometriccolours of B stars in the red and infrared. From these intrinsic coloursthe interstellar reddening relationships for the red and infraredcolours are evaluated, and the results are compared with previousestimates of these quantities. The values of R, E(B-V) and the distanceare then determined for the individual stars. R is confirmed to be closeto 3.1 in most cases, but was found to be much larger in somedirections. The relationship between R and the location of a star in theGalaxy is investigated. Usually the abnormally reddened stars seemed tobe associated with known regions of star formation. The paper alsoidentifies seven likely variable stars and a number of stars withpossible dust shells.
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A Radial Velocity Database for Stephenson-Sanduleak Southern Luminous Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113..823R&db_key=AST
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A spectroscopic database for Stephenson-Sanduleak Southern Luminous Stars
A database of published spectral classifications for objects in theStepenson-Sanduleak Luminous Stars in the Southern Milky Way catalog hasbeen compiled from the literature. A total of 6182 classifications for2562 stars from 139 sources are incorporated.
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Millimetre observations of southern translucent clouds
Millimetre emission line observations of ^12^CO J=1-0 are presented fora sample of translucent molecular clouds previously studied by opticalabsorption lines towards background stars. The CO maps provideinformation on the extent, structure, mass and kinematics of theregions. In some clouds, the emission is characterized by a singlecomponent which does not vary much across the region. In other cases,multiple close-lying components or sheets are found, which may vary in aself-similar manner across the cloud. None of the clouds is close tosimple virial equilibrium. Sensitive searches for ^13^CO and C^18^OJ=1-0 emission have been made towards the stellar positions. C^18^O hasbeen detected in only 5 clouds, most of which have extinctions well inexcess of 2 mag. The inferred ^13^CO/C^18^O abundance ratios range from7-25, and the lower limits from >13 to >35. These values are asmuch as five times larger than the overall interstellar([^13^C].[^16^O])/([^12^C] .[^18^O]) ratio, suggesting thatisotope-selective photodissociation plays a role in at least some of theclouds. Searches for other molecules at millimetre wavelengths have beenmade for a few of the best characterized clouds. Surprisingly, noemission was detected from the C_2_H or C_3_H_2_ molecules, even thoughthe abundances of diatomic C_2_ and CH are quite large. On the otherhand, the abundance of HCO^+^ appears comparable to that found in denserclouds, and the abundance of HCN may be up to an order of magnitudelarger than the predictions of models in two clouds.
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The abundance of CH(+) in translucent molecular clouds - Further tests of shock models
Observations of interstellar absorption lines of CH(+) in the (0, 0) and(1, 0) bands of the A 1Pi - X 1Sigma(+) system are presented for 17stars with reddenings up to E(B-V) about 1.5 mag. Complementary data oninterstellar CH in the (0, 0) bands of the A 2Delta - X 2Pi and B2Sigma(-) - X 2Pi systems and C2 in the A 1Pi(u) - X 1Sigma(g)(+) redsystem have been obtained as well. The derived CH(+) column densitiescontinue to increase with total column density, and values up to 10 exp14/sq cm are reported for highly-reddened lines of sight. In most cases,the CH(+) and CH absorptions are dominated by a single strong component,with weaker features displaced by a few km/s. No significant velocitydifference is found between CH(+) and neutral species such as CH and CNfor this sample of randomly oriented lines of sight. In contrast withCN, the CH(+) abundance does not increase with the density in the cloudas derived from the observed C2 excitation. For the two clouds with thelargest density, HD 62542 and HD 94413, no CH(+) absorption is foundwith CH(+)/CH less than 0.03 and 0.14, respectively. The CH(+) findingsdo not support a single-shock origin for the formation of the ion.
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Interstellar C2, CH, and CN in translucent molecular clouds
Optical absorption-line techniques have been applied to the study of anumber of translucent molecular clouds in which the total columndensities are large enough that substantial molecular abundances can bemaintained. Results are presented for a survey of absorption lines ofinterstellar C2, CH, and CN. Detections of CN through the A 2Pi-X2Sigma(+) (1,O) and (2,O) bands of the red system are reported andcompared with observations of the violet system for one line of sight.The population distributions in C2 provide diagnostic information ontemperature and density. The measured column densities of the threespecies can be used to test details of the theory of molecule formationin clouds where photoprocesses still play a significant role. The C2 andCH column densities are strongly correlated with each other and probablyalso with the H2 column density. In contrast, the CN column densitiesare found to vary greatly from cloud to cloud. The observations arediscussed with reference to detailed theoretical models.
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UBV-beta photometry of luminous early-type stars and emission-line stars in the Southern Coalsack region
A catalog is presented giving UBV-beta photometry for 144 luminous OBstars and UBV photometry for 154 emission-line stars in a 100-sq-degregion around the Southern Coalsack. Total visual absorptions anddistance moduli have been determined for all the stars and aretabulated. Comparisons with previous observations are discussed.
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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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On the 4430 A interstellar band - A visual classification
A system of visual classification of the strength of the interstellarband 4430 A has been developed, based on spectra taken at spectralclassification dispersion. The intensity of the band was divided into 8main classes, defined by a group of selected standard stars. The systemwas applied to 1,111 southern OB stars contained in the catalog ofspectral types by Garrison, Hiltner, and Schild (1977). The mean errorin the classification was estimated to be plus or minus 1 class.Equivalent widths were measured for 100 stars; an excellent correlationwith the visual estimations was obtained. A calibration between thesetwo parameters is given.
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MK spectral classifications for southern OB stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJS...35..111G&db_key=AST
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O stars and supergiants south of declination -53 0.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..116H&db_key=AST
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Structure and motions in the CAR spiral feature.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&A....20...29H&db_key=AST
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Estrellas de alta luminosidad entre Vela y Cruz. II.
Not Available
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INHABITED SKY
