Dust properties along anomalous extinction sightlines
The large majority of extinction curves in our own Galaxy obey to asimple relation depending on one parameter, the total-to-selectiveextinction coefficient, RV. Different values of RVare able to match the whole extinction curve through differentenvironments. However, anomalous curves still exist in our own Galaxy.In this paper, we aim at analysing the behaviour of some anomalousextinction curves in order to shed light into both the properties of thedust and the physical properties of their environments. From thecatalogue of Savage et al., by adding the infrared data from Two-MicronAll-Sky Survey catalogue, 84 lines of sight (i.e. ~=11 per cent) havebeen selected which deviate at the 2? level from the normalextinction law corresponding to their best-fitting RV value.We single out a subsample of 20 lines of sight to analyse theirultraviolet (UV) deviations, in particular, at ? = 0.22 and0.15?m, which correspond to the bump and the far-UV rise. The linesof sight with bump lower and far-UV rise higher than their normalextinction law are defined as type A anomalous lines, and those withbump higher and far-UV rise lower as type B anomalous lines. The resultshere discussed are derived from extinction curve models. A anomaloustypes require small-to-large grain-size ratios larger than the normalcurves both for silicates and carbonaceous grains; B curves also requirelarger ratios for carbonaceous ones but lower ratios for silicatesgrains. In order to interpret these results, the environments of type Acurves require low-velocity shocks in order to make effective thegrain-grain collisions, which increase the number of both small silicateand carbonaceous grains. However, type B lines of sight would becharacterized by relatively high-velocity shocks, implying a sputteringprocess which sensibly destroys small silicate grains while it producesonly a partial destruction of the carbonaceous ones with the consequenceof increasing the number of these smaller particles.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
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Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
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Observational Evidence of Supershell Blowout in GS 018-04+44: The Scutum Supershell
Emission in the H I 21 cm line has been mapped for a region of theGalaxy that includes two known supershells, GS 018-04+44 and GS034-06+65. We focus on the GS 018-04+44, hereafter referred to as theScutum Supershell, which is an elongated shell about 5 deg in diameterextending to -7 deg below the Galactic plane. The Scutum shell lies at akinematic distance of ~3300 pc, implying a shell diameter of ~290 pcwith a vertical extension of ~400 pc away from the Galactic plane. TheScutum shell contains 6.2x105 Msolar swept intothe walls. We observe that the top of the shell is missing, and asubstantial column of H I rises from the shell walls tob=-11deg, culminating in a large cloud of neutral hydrogen,3.74x104 Msolar, located ~630 pc from the plane.ROSAT data show X-ray emission that closely anticorrelates with the 21cm emission. This emission probably originates from hot gas within theScutum Supershell. After approximately correcting for the foregroundabsorption, we find that the 1.5 keV X-rays peak at the base of theshell, the 0.75 keV emission peaks in the interior and at the top of theshell, and the 0.25 keV emission extends to high latitudes above theshell. The X-ray luminosity is roughly ~5x1036 ergss-1. The Wisconsin Hα Mapper (WHAM) survey shows thepresence of Hα emission that exhibits a morphology similar to thatof the H I. Spectra indicate the presence of ionized hydrogen atvelocities similar to the H I, placing ionized material at the samekinematic distance as the neutral material. IRAS images in the 60 and100 μm wavebands reveal the presence of dust correlated with theneutral hydrogen. Infrared surface brightness indicates an excess in the100 μm emission, which could indicate a molecular hydrogen componentwith a column density of 2.4x1021 cm-2 in thedensest regions of the high-latitude cloud of neutral hydrogen. IUEultraviolet high dispersion spectra of HD 177989 (l=17.89d, b=-11.88d)and HD 175754 (l=16.40d, b=-9.92d) reveal the presence of very strongabsorption by highly ionized gas at a velocity that associates theabsorption with the ejecta of the Scutum Supershell. In the case of HD177989, the high ion column density ratios suggest an origin in aturbulent mixing layer where hot and cool gases mix in the presence ofshear flows. The Hα and X-ray emission suggest that a multitude ofenergetic phenomena exist in this region, providing the necessaryionizing radiation. Indeed, there are multiple supernova remnants, H IIregions, and hot stars, which could all contribute sizeable amounts ofenergy and ionizing radiation. The combination of these data setsindicates observational evidence of a ``blowout'' phenomena whereby hotmaterial produced within the Scutum Supershell has blown through the topof the shell and been pushed to high latitude. Based on observationsfrom the Green Bank 43m radio telescope, the ROSAT All-Sky Survey, theWHAM All-Sky Survey, IRAS, and IUE.
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Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
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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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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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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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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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Photoelectric photometry of OB stars in the Vilnius system
Not Available
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The interstellar 217 NM band - A third catalogue of equivalent widths
A catalog of equivalent widths of the 217 nm interstellar absorptionband as well as other parameters characterizing the extinction curve inthe ultraviolet has been compiled for 790 O and B stars. A relativelytight correlation between the equivalent width of the 217 nm band andE(B-V) indicates that the absorber of this band is connected with thepopulation of larger interstellar grains responsible for the visualextinction. The parameter characterizing the amount of extinction in thefar UV is only weakly correlated with E(B-V), a result in accord withthe assumption that a second population of very small grains causes therapid increase of the far-UV extinction.
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A catalog of ultraviolet interstellar extinction excesses for 1415 stars
Ultraviolet interstellar extinction excesses are presented for 1415stars with spectral types B7 and earlier. The excesses with respect to Vare derived from Astronomical Netherlands Satellite (ANS) 5-channel UVphotometry at central wavelengths of approximately 1550, 1800, 2500, and3300 A. A measure of the excess extinction in the 2200-A extinction bumpis also given. The data are valuable for investigating the systematicsof peculiar interstellar extinction and for studying the character of UVinterstellar extinction in the general direction of stars for which theextinction-curve shape is unknown.
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A comparison of photometric and kinematic distances for southern H II regions
Candidates for exciting stars have been examined in 49 southern H IIregions by means of photoelectric UBV and H-beta photometry. Thephotometric distances of the related stars are compared with thekinematic distances of the corresponding H II regions as given byGeorgelin et al. (1973). In the range l 250 deg through 360 deg to 30deg there are no systematic differences. Only a region in Puppis at labout 230 deg yields photometric distances which systematically exceedthe kinematic ones. It is shown that an abnormal R-value cannot accountfor the observed discrepancy in this region.
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UBV photometry of OB+ stars north of 1950.0 declinaison -15.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..128D&db_key=AST
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A catalogue of galactic O stars. The ionization of the low density interstellar medium by runaway stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974RMxAA...1..211C&db_key=AST
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A new general O type stars catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&AS...12..277G&db_key=AST
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Studies in Galactic STRUCTURE.II.LUMINOSITY Classification for 1270 Blue Giant Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJS....2...41M&db_key=AST
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A Finding List of O and B Stars of High Luminosity.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...113..141N&db_key=AST
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INHABITED SKY
