Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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13CO (J = 1 -- 0) Survey of Molecular Clouds toward the Monoceros and Canis Major Region
rough a large-scale 13CO(J=1-0) survey toward a region inMonoceros and Canis Major, we present following results: (1) Weidentified in total 115 clouds. (2) GroupI (CMaOB1 and G220.8 ‑1.7) may physically connected with GroupII (Mon R2 and NGC2149). (3)496YSO candidates were chosen from IRAS point source catalog (IPC). (4)The mass spectrum of the Local clouds shows a power-law relation with anindex of ‑1.55 ± 0.09. (5) The number fraction ofstar-forming clouds increases as the cloud mass increases. Especially,massive clouds of Mcloud≥103.5Modot are all star-forming clouds. (6) Theline width-cloud radius relation is best fitted asΔVcomp ∝ rcloud0.47(correlation coefficient = 0.87). (7) The distribution of(Mvir / Mcloud) shows that star-forming cloudstend to be more virialized than no star-forming clouds. (8) Starformation in GroupI is more active than that in GroupII. (9) Unexpectedsmall number of low-mass clouds in GroupI may be due to strong UVradiation from O-type stars in the vicinity of the clouds. (10) Starformation in GroupII might occurred by self-gravitational, except forthe most massive cloud.
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Merged catalogue of reflection nebulae
Several catalogues of reflection nebulae are merged to create a uniformcatalogue of 913 objects. It contains revised coordinates,cross-identifications of nebulae and stars, as well as identificationswith IRAS point sources.The catalogue is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/141
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2MASS Observations of the Perseus, Orion A, Orion B, and Monoceros R2 Molecular Clouds
We use the 2MASS Second Incremental Release Point Source Catalog toinvestigate the spatial distribution of young stars in the Perseus,Orion A, Orion B, and MonR2 molecular clouds. After subtracting asemiempirical model of the field star contamination from the observedstar counts, stellar surface density maps are used to identify compactclusters and any stellar population found more uniformly distributedover the molecular cloud. Each cloud contains between two and sevenclusters, with at least half of the cluster population found in asingle, rich cluster. In addition, a distributed stellar population isinferred in the Orion A and MonR2 molecular clouds within theuncertainties of the field star subtraction with a surface densitybetween 0.013 and 0.083 arcmin-2. Sensitivity calculationssuggest, however, that the number of stars in the distributed populationmay be underestimated by a factor of 2 or more if stars have beenforming with a Miller-Scalo IMF at a constant star formation rate forlonger than 10 Myr. After considering the possible evolutionary statusof the distributed population, the global star formation efficiencyimplied by the sum of the distributed and cluster populations rangesbetween 1% and 9% among the four clouds. The fraction of the totalstellar population contained in clusters for the nominal extinctionmodel ranges from ~50% to 100% if the distributed population isrelatively young (<10 Myr), to ~25%-70% if it is relatively old (~100Myr). The relatively high fraction of stars contained in clustersregardless of the age of the distributed population, in conjunction withthe young ages generally inferred for embedded clusters in nearbymolecular clouds, indicates that a substantial fraction of the totalstellar population in these regions has formed within the past fewmillion years in dense clusters. This suggests that either the starformation rate in each these clouds has recently peaked if one assumesclouds have ages greater than 10 Myr or molecular clouds are youngerthan typically thought if one assumes that the star formation rate hasbeen approximately constant in time.
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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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CH(+) in the interstellar medium
This paper describes observations of interstellar CH(+) along the linesof sight to O and B stars with E(B-V)s up to +1.13. Along some lines ofsight with strong detections of CH(+), we find distinct radial velocityshifts between the CH(+) lines and other neutral species, such as Ca Iand CH. The shifts are small but are predicted by shock models of CH(+)formation in which the shock is inclined with respect to the observer.We have also found no column densities exceeding approximately1013.8/sq cm. When these data are examined along with theother CH(+) data collected from the literature, the previously seentendency of CH(+) column density to increase with E(B-V) does notcontinue beyond reddenings of about +0.6. These findings offer supportto the shock model of CH(+) formation for at least some lines of sight.
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Diffuse interstellar bands in Orion: The environment dependence of DIB strength
Four Diffuse Intersellar Bands (DIB) have been measured in 22 lines ofsight towards Orion and GMC214-13. The paper reports on the environmentdependence of DIB strength, using reddening, the total extinction in thevisual, and column densities of various forms of hydrogen as indicatorsof line of sight conditions. In lines of sight with small reddening,EB-V less than 0.08 mag, a weakening of lambda(6284) andlambda(5785) is found relative to reddening (= all matter), but noweakening relative to atomic + molecular hydrogen (= all neural matter).This probably implies that the DIB carriers are absent in the ionisedHII medium. At higher reddening, where a significant part of hydrogen isan molecular form, all DIBs in Orion decrease with increasingEB-V in a similar way as is known for the Taurus andOphiuchus dark clouds. In Taurus, where even in low reddened lines ofsight a significant part of hydrogen is in molecular form, lambda(6284)is weakened compared to diffuse medium values at lower reddening thanlambda (6196). In lines of sight towards the Orion Nebula, wheremolecular hydrogen is mostly dissociated, lambda(6284) is some 70%stronger, while lambda(6196) is a factor of 5 weaker than expected fromthe above dependence. The results are discussed in the context that thecarrier of the diffuse bands might be a large molecule in ionised form.The dissociation and ionisation state of hydrogen is used as anindicator of the UV field. The results above indicate that thelambda(6284) carrier is both ionised and destroyed by higher energyphotons than the lambda(6196) carrier, which is consistent with amolecular carrier.
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Far-ultraviolet stellar photometry: A field in Orion
Far-ultraviolet photometry for 625 objects in Orion is presented. Thesedata were extracted from electrographic camera images obtained duringsounding rocket flights in 1975 and 1982. The 1975 images were centeredclose to the belt of Orion while the 1982 images were centeredapproximately 9 deg further north. One hundred and fifty stars fell inthe overlapping region and were observed with both cameras. Sixty-eightpercent of the objects were tentatively identified with known starsusing the SIMBAD database while another 24% are blends of objects tooclose together to separate with our resolution. As in previous studies,the majority of the identified ultraviolet sources are early-type stars.However, there are a significant number for which no such identificationwas possible, and we suggest that these are interesting objects whichshould be further investigated. Seven stars were found which were brightin the ultraviolet but faint in the visible. We suggest that some ofthese are nearby white dwarfs.
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Uvby-beta observations of 528 type B stars with V between the 8th and 9th magnitude
The paper presents uvby-beta measurements of 528 type B stars selectedfrom the SAO Catalog on the basis of two criteria: the spectral types inthe range B3-B5 and mV between the 8th and the 9th magnitude. Reddeningindependent (c1) values are estimated from the spectral classificationand compared to the observed values. No systematic trend with observed(b-y), H-beta, or spectral type appears to be present, but the range of(c1) residuals is surprisingly large. A rather large part of the starshas small beta values, smaller than for the BIa supergiants. Only twoare classified as O stars and most of them have the suffix e, ne, ornne. Most beta values for the O type stars are slightly above the upperlimit of 2.585 m.
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The galactic reddening law - The evidence from uvby-beta photometry of B stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&A...142..189T&db_key=AST
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Polarization of stars in R-associations - Observational data
Polarimetric data are assembled for 95 stars that are illuminatingreflection nebulae. Most of these belong to 18 standard R-associations.The observed dependence of the percentage polarization P on wavelengthand color excess E(B-V) suggest that the unpolarized light ofR-association members may become polarized as it traverses an ensembleof dust grains aligned by a magnetic field which in some cases (Tau R2,Ori R1/R2, Sco R1, Cep R2) is intrinsic to the association. In certainR-associations the grain size is variable and the stochastic magneticfield component fluctuates on a scale of 10-30 pc.
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Optical observations of ultraviolet objects. I - Spectral classification of 103 stars /l = 200-275 deg/
Results are presented of a program of spectral classification of 103stars originally selected as ultraviolet objects from TD-1 satellitephotometry with the S2/68 experiment. Most of the objects appear to bespectroscopically normal stars; the method of selection yielded a sampleof relatively unreddened B stars at distances up to about 2 kpc. Thisresult is compared with recent studies of the spatial distribution ofinterstellar extinction in the same regions of the sky.
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H-beta photometry of southern early-type stars
H-beta photoelectric photometry is presented for 209 southern hemisphereearly-type stars from the HD catalog with galactic latitudes /b/ greaterthan 6 deg. Four-color photometry exists for all these stars and MKtypes for most of them. Absolute magnitudes have been estimated for allbut the emission-line stars and distances from the sun and the galacticplane determined.
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Molecular clouds associated with reflection nebulae. I - A survey of carbon monoxide emission
The paper presents 2.6 mm wavelength CO and (C-13)O observations of 130molecular clouds associated with reflection nebulae. Enhanced COemission was found in the vicinity of the illuminating star in abouthalf the objects studied. There is a tendency for the CO peak to beslightly displaced from the star. Many examples of peaks that appear toresult from heating of the cloud by the nearby star are found, whileothers appear to be associated with independent concentrations ofmaterial.
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Evidence for an abundance gradient in the galactic disk
DDO photometry of field K giants in distant parts of the galactic diskin the galactic center and anticenter directions is used together withDDO and UBV photometry of 41 open clusters to investigate the variationof metallicity across the galactic disk. Some problems in thecalibration of DDO photometry are examined, and the observations areanalyzed. The data are shown to be consistent with the suggestion thatthere is a composition gradient among stars of all ages in the galacticdisk. Specifically, it is found that: (1) the metallicity gradient inthe solar vicinity is approximately -0.05/kpc; (2) the gradient maybecome steeper beyond a galactocentric distance of approximately 11 kpc;(3) the nitrogen gradient is more pronounced than the overall gradient;and (4) the gradient in the youngest stellar population is probably notdramatically different from the overall gradient
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Four colour photometry of southern early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978MNRAS.182..629K&db_key=AST
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R associations. V. MON R2.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..840H&db_key=AST
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Stars in reflection nebulae
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..233R&db_key=AST
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A study of reflection nebulae.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966AJ.....71..990V&db_key=AST
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The Radial Velocities of Faint Class B Stars in the Declination Zone 0° to -23°.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1943ApJ....97..300N&db_key=AST
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INHABITED SKY
