The CH2CN- molecule: carrier of the λ8037 diffuse interstellar band?
The hypothesis that the cyanomethyl anion CH2CN- isresponsible for the relatively narrow diffuse interstellar band (DIB) at8037.8±0.15 Å is examined with reference to newobservational data. The 0_00 absorption band arising from the^1B_1-tildeX ^1A' transition from the electronic ground state to thefirst dipole-bound state of the anion is calculated for a rotationaltemperature of 2.7 K using literature spectroscopic parameters andresults in a rotational contour with a peak wavelength of 8037.78Å. By comparison with diffuse band and atomic line absorptionspectra of eight heavily-reddened Galactic sightlines, CH2CN-is found to be a plausible carrier of the λ8037 diffuseinterstellar band provided the rotational contour is Doppler-broadenedwith a b parameter between 16 and 33 km s-1 that depends onthe specific sightline. Convolution of the calculated CH2CN-transitions with the optical depth profile of interstellar Ti II resultsin a good match with the profile of the narrow λ8037 DIB observedtowards HD 183143, HD 168112 and Cyg OB2 8a. The rotational levelpopulations may be influenced by nuclear spin statistics, resulting inthe appearance of additional transitions from Ka = 1 of orthoCH2CN- near 8025 and 8050 Å that are not seen incurrently available interstellar spectra. For CH2CN- to bethe carrier of the λ8037 diffuse interstellar band, either a)there must be mechanisms that convert CH2CN- from the orthoto the para form, or b) the chemistry that forms CH2CN- mustresult in a population of K_a'' levels approaching a Boltzmanndistribution near 3 K.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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A Method for Simultaneous Determination of AV and R and Applications
A method for the simultaneous determination of the interstellarextinction (AV) and of the ratio of total to selectiveextinction (R), derived from the 1989 Cardelli, Clayton, & Mathisfitting of the interstellar extinction law, is presented and applied toa set of 1900 color excesses derived from observations of stars inUBVRIJHKL. The method is used to study the stability of AVand R within selected regions in Perseus, Scorpius, Monoceros, Orion,Sagittarius, Ophiuchus, Carina, and Serpens. Analysis shows that R isapproximately constant and peculiar to each sector, with mean valuesthat vary from 3.2 in Perseus to 5.6 in Ophiuchus. These results aresimilar to published values by Aiello et al., He et al., Vrba &Rydgren, O'Donnell, and Cardelli, Clayton, & Mathis.
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The total-to-selective extinction ratio determined from near IR photometry of OB stars
The paper presents an extensive list of the total to selectiveextinction ratios R calculated from the infrared magnitudes of 597 O andB stars using the extrapolation method. The IR magnitudes of these starswere taken from the literature. The IR colour excesses are determinedwith the aid of "artificial standards" - Wegner (1994). The individualand mean values of total to selective extinction ratios R differ in mostcases from the average value R=3.10 +/-0.05 - Wegner (1993) in differentOB associations. The relation between total to selective extinctionratios R determined in this paper and those calculated using the "methodof variable extinction" and the Cardelli et al. (1989) formulae isdiscussed. The R values presented in this paper can be used to determineindividual absolute magnitudes of reddened OB stars with knowntrigonometric parallaxes.
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Atlas of Interstellar Extinction Curves of OB Stars Covering the Whole Available Wavelength Range
The paper presents a collection of 436 extinction curves covering thewhole available range of wavelengths from satellite UV to near-IR. Thedata were taken from the ANS photometric catalogue and from thecompilations of IR photometric measurements. The data curves have beenobtained with the aid of ``artificial standards": Papaj et al. (1993)and Wegner (1994, 1995). The visual magnitudes and spectralclassifications of O and B type stars with EB-V>= 0.05were taken from the SIMBAD database. The curves are given in the form ofplots and tables E{lambda - V} / EB-V versus1/λ. The observed variety of extinction laws among slightlyreddened stars is apparently due to the various physical parameters ofinterstellar clouds.
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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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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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H-beta Photometry of Southern Luminous Stars
H-beta photometry for 116 stars listed in Stephenson and Sanduleak's(1971) catalog of _Luminous Stars in the Southern Milky Way_ isreported. The vast majority of these objects are O and B-type stars; afew are A, F, or Wolf-Rayet stars. A systematic difference of on theorder of 30 mmag between the present results and those of otherinvestigators is noted. (SECTION: Stars)
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Interstellar Extinction from 0.35 to 2.2 Microns: A Study Based on Luminous Southern Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS..101..335H&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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Stroemgren and H beta photometry of OB stars in Serpens
Stroemgren and H beta photometry of 25 stars in the field of Serpens arepresented. The excesses, the absolute magnitude and the temperatures ofthe stars are obtained. The masses and the ages are also estimated.
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A study of reddened luminous stars in the southern Milky Way. IV. JHK photometry.
Not Available
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A study of reddened luminous stars in the southern Milky Way. III. VRI photometry.
Not Available
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A study of reddened luminous stars in the southern Milky Way. II. H-beta photometry, reddening and distances.
Not Available
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A study of reddened luminous stars in the southern Milky Way. UVBY photometry.
Not Available
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High-velocity interstellar gas toward HD 169454
The interstellar spectrum of HD 169454 reveals Na D and Ca K absorptionat about + 100 km/s. Measurements made at high resolution resolve 4narrow (about 2-3 km/s) features whose N(Ca II)/N(Na I) ratios aresmall. This high-velocity gas is, therefore, unique in that it resembleslocal quiescent gas, not shocked gas. Redshifted gas is also seen inmoderate-resolution spectra of faint stars lying in the same portion ofthe sky as HD 169454. The resulting picture is one in which a supernovaexplosion or stellar winds within the Sct OB3 association at a distanceof about 1.5 kpc is pushing quiescent gas away from the sun. The gas isseen only in stars estimated to be at most 3 kpc, but greater than 2kpc, away. If HD 169454 is at this greater distance, its absolutemagnitude would be about -9, making it the second most luminous B starin the Galaxy.
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Groups of stars with common motion in the Galaxy. Groups of O and B stars
Not Available
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The spectral energy distribution of early-type stars. II - The extinction law towards O-type stars
Photometric measurements through different pass-bands are used todetermine the color-excess E(B-V) for O-type stars in the UV and IRspectral regions. The results are used to examine the extinctioncharacter of the stars. It is found that, in the UV, each O-type starhas its own extinction character. In general, the visual and NIRextinction in the direction of O-type stars are normal.
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The visually brightest early-type supergiants in the spiral galaxies NGC 2403, M81, and M101
Moderate-resolution spectroscopy of the candidate brightest blue starsin the nearby spirals NGC 2403, M81, and M101 reveals that many are notsingle stars, but compact H II regions, clusters, and multiple systems.This is an additional and serious limitation on their use as distanceindicators. The derivation of the luminosities of the confirmed singleblue supergiants is discussed, and, combining these results withprevious work on the brightest red supergiants, a brief discussion andcomparison of the evolution of their most massive stars are given. Theproperties of the brightest blue and red stars in NGC 2403 and M81 arebasically in agreement with the pattern of massive-star evolutionobserved in Local Group galaxies. The distance to M101 is stillcontroversial, but at the larger distance modulus, the luminosities ofits brightest early and late-type supergiants place them beyond theEddington limit for their initial mass and temperature.
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The spectral energy distribution of early type stars. I - A catalogue of photometric data of 259 stars from 0.15 to 4.8 microns
For the derivation of physical parameters (e.g., effective temperatureand radius) of early-type stars from their intrinsic spectral-energydistribution, and for the study of foreground interstellar and/orcircumstellar matter, a sample of 237 O, B, and A stars was chosen fromthe ANS catalog (Wesselius et al., 1982). The ANS ultraviolet and theJohnson UBV data (mostly from Nicolet's catalog, 1978) of these starswere supplemented with visual Walraven WULBV, red VRI, and near-infraredJHKLM measurements. All these data are given in the present catalog.Data for 22 stars of spectral type later than A are also included.
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Early-type stars in OB associations in the infrared. I Extinction law and IR excesses
Observations have been made of 82 early-type stars of OB associations inthe infrared (JHKLM). The law of interstellar extinction isinvestigated. The empirical reddening curve (with R = 3.13) is found tobe in close agreement with van de Hulst's (1949) theoretical curve No.15. This law is generally valid for the OB associations considered. Themeasured infrared magnitudes were dereddened with this extinction law,and compared with the prediction of model atmospheres. Significantinfrared excesses due to circumstellar free-free radiation are found fora large number of stars. The strongest IR excess (about 0.5 mag in M) isfound for the Of-type stars HD 108, HD 151804, and HD 152408. In late Bsupergiants no significant excess radiation is detectable. However, thevery luminous hypergiants HD 168607 and HD 168625 do show excessradiation of about 0.2 mag in M.
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New UBVRI photometry for 900 supergiants
A description is presented of the results obtained in connection with asystematic program of supergiant photometry on the Johnson UBVRI system.During the eight years after the start of the program, almost 1000 starshave been observed, about 400 three or more times each. The originalselection of stars used the spectral type catalog of Jaschek et al.(1964) to choose supergiants. Since observations were possible from bothChile and Canada, no declination limits were imposed, and no particularselection criteria were imposed other than to eliminate carbon stars.These are so red as to require enormous extrapolations of thetransformation equations.
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A survey of interstellar neutral potassium. I - Abundances and physical conditions in clouds toward 188 early-type stars
Observations of interstellar absorption in the resonance doublet 7664,7698 A of neutral potassium toward 188 early-type stars at a spectralresolution of 8 km/s are reported. The 7664 A line is successfullyseparated from nearly coincident telluric O2 absorption for all but afew of the 165 stars for which K I absorption is detected, makingpossible an abundance analysis by the doublet ratio method. Therelationships between the potassium abundances and other atomicabundances, the abundance of molecular hydrogen, and interstellarreddening are investigated.
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Infrared photometry of southern early-type stars
The paper presents infrared photometry tied to the JHKL (1.2-3.5microns) broadband photometric system for 229 southern early-type stars.To determine data for stars of low reddening intrinsic visual-IR colorindices were used; the E(V-K)/E(B-V) diagram was applied to evaluate theratio of total selective extinction. A mean value of R = 3.12 plus orminus 0.05 was found for stars close to the galactic plane, but a highervalue of R (about 4.0) applies to the Orion and Sco-Oph regions.Infrared two-color diagrams were used to investigate the occurrence ofinfrared excess emission in different classes of shell star; no excesseswere found for supergiants or Of stars. It is concluded that theanomalous position HD 164740 in the two-color diagrams is produced bystrong infrared excess and not by a peculiar extinction law.
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Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..309H&db_key=AST
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High-resolution profiles of the diffuse interstellar features at 6379 and 6614 A
Abstract image available at:http://adsabs.harvard.edu/abs/1977ApJ...215..788W
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The diffuse interstellar bands. IV - The region 4400-6850 A
It is shown that 39 diffuse bands lying between 4400 and 6850 A can beregarded as certainly or probably interstellar bands. Of these, 24 bandsare described in detail. These, and seven additional features which maybe interstellar are tabulated. For those 17 bands for which the data aremost extensive, the correlation of equivalent width with the colorexcess ranges from good to excellent when regional effects and errors ofobservation are taken into consideration. To a good first approximation,the entire diffuse line spectrum strengthens together with and in directproportion to increasing interstellar extinction. This result supportsthe hypothesis that the diffuse lines can properly be regarded as finestructure in the interstellar extinction curve.
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INHABITED SKY
