Magnetic fields of chemically peculiar stars. I. The catalog of magnetic CP stars
This is the first paper of the series dedicated to the analysis of themagnetism of chemically peculiar (CP) stars of the upper Main Sequence.We use our own measurements and published data to compile a catalog ofmagnetic CP stars containing a total of 326 objects with confidentlydetected magnetic fields and 29 stars which are very likely to possessmagnetic field. We obtained the data on the magnetism of theoverwhelming majority of the stars solely based on the analysis oflongitudinal field component B e . The surface magneticfield, B s , has been measured for 49 objects. Our analysisshows that the number of magnetic CP stars decreases with increasingfield strength in accordance with exponential law, and stars with B e exceeding 5kG occur rarely (about 3% objects of ourlist).
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New magnetic chemically peculiar stars
Spectropolarimetric observations of 96 chemically peculiar (CP)main-sequence stars have been carried out at the 6-m telescope at theSpecial Astrophysical Observatory of the Russian Academy of Sciences(SAO RAS) with the aim of searching for the presence of stellar magneticfields. The stars selected for investigation were CP stars known to havestrong anomalies in the wavelength region of the continuum fluxdepression around λ 5200Å. This selection was conductedwith the aid of low-resolution spectral observations, made with the SAORAS 1-m telescope, and of published differential photometric data.Magnetic fields have been successfully detected in 72 stars of whichonly three stars were previously known to have magnetic fields. For twostars, the longitudinal component of the magnetic field Beexceeds 5 kG: HD178892 - 7.4 kG, and HD258686 - 6.7 kG. We failed toreliably detect the magnetic field in the other 24 CP stars. These starsare mostly fast rotators, a feature which hampers accurate measurementsof Be. It is demonstrated in this paper that selectingcandidate magnetic stars by considering their photometric indices Z orΔa, or alternatively, by inspecting low-resolution spectra aroundthe λ5200Å flux depression, considerably increases thedetection rate.This paper is based on data obtained at the 6-m telescope of the RussianAcademy of Sciences.E-mail: dkudr@sao.ru
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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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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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Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
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The HR-diagram from HIPPARCOS data. Absolute magnitudes and kinematics of BP - AP stars
The HR-diagram of about 1000 Bp - Ap stars in the solar neighbourhoodhas been constructed using astrometric data from Hipparcos satellite aswell as photometric and radial velocity data. The LM method\cite{luri95,luri96} allows the use of proper motion and radial velocitydata in addition to the trigonometric parallaxes to obtain luminositycalibrations and improved distances estimates. Six types of Bp - Apstars have been examined: He-rich, He-weak, HgMn, Si, Si+ and SrCrEu.Most Bp - Ap stars lie on the main sequence occupying the whole width ofit (about 2 mag), just like normal stars in the same range of spectraltypes. Their kinematic behaviour is typical of thin disk stars youngerthan about 1 Gyr. A few stars found to be high above the galactic planeor to have a high velocity are briefly discussed. Based on data from theESA Hipparcos astrometry satellite and photometric data collected in theGeneva system at ESO, La Silla (Chile) and at Jungfraujoch andGornergrat Observatories (Switzerland). Tables 3 and 4 are onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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CP2 stars as viewed by the UVBY H_beta system
The aim of this work is to study the capacity of the uvby H_βsystem for detecting the chemically peculiar (CP) stars based on theeffect that peculiar features in the flux distribution have on all theStromgren-Crawford indices. Our study focuses on the classical magneticpeculiar stars (CP2), though Am stars (CP1) are also included forcomparison with cool CP2 stars. Satisfactory results were obtained forhot CP2 stars: the definition of a new index p, which is a linearcombination of uvby H_β colours, allowed us to separate a highpercentage of hot CP2 stars from normal stars. According to this newindex, 60 new CP2 candidates are proposed. The working sample wasextracted from The General Catalogue of Ap and Am stars by \cite[Rensonet al. (1991)]{ren91}. Photometric observations to enlarge the sample ofCP2 stars with complete uvby H_β photometry were carried out. Theseobservations are also reported in the present paper. The new index p isalso used to correct the reddening of early CP2 stars computed as ifthey were normal stars. Tables 2, 3 and 7 are also available inelectronic form from CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
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A new CO survey of the Monoceros OB1 region.
A new, fully sampled, sensitive CO survey of 52.5 square degrees towardsthe Monoceros OB1 (Mon OB1) region has been completed using the CfA 1.2m millimeter-wave radio telescope. This survey extends from b=-1.5°to b=+3.5° and from l=196.0° to l=206.5° on a uniformlyspaced grid of 3.75' in l and b, and has substantially bettersensitivity than previous surveys of the region. CO is detected in 80%of the area, 60% of which is weak with integrated intensities less than5K.km/s. The large-scale kinematics are dominated by the Perseus andLocal spiral arms. Within the Local arm the molecular gas appears tohave been strongly influenced by supernova remnants and expanding HIIregions with the strongest emission at velocities ranging from -17 to+10km/s, and a total mass of 1.3x10^5^Msun_. Weak CO emissionfrom Perseus arm clouds shows that they have a mean kinematic distanceof 3.5kpc and are comparable in size and mass to local molecular clouds.The coincident positions of colour selected IRAS point sources indicatesthat these distant clouds are undergoing massive star formation.
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A new list of effective temperatures of chemically peculiar stars. II.
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Liste des étoiles Ap et Am dans les amas ouverts (édition révisée)
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Observations in regions of Cassiopeia, Gemini, and Monoceros with the Glazar space telescope
Observations at 1640 A of regions in Cassiopeia, Gemini, and Monocerosmade with the Glazar space telescope are presented; 7, 11, 13, and 35early-type stars brighter than about 9 mag were detected in the observedregions. The distribution of dust matter in the corresponding regions isstudied. It is determined that companions of HD 4442, 4797, and BD + 62deg 2225 are subdwarfs of sdB - sdO types; the hot companion of HD220102 may be of the type from B8 Ib-II to sdB. It is shown that HD 5233and 261490 are probably embedded in dense circumstellar envelopes.
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The young open clusters NGC 2244 and NGC 2264
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991RMxAA..22...99P&db_key=AST
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Liste des étoiles Ap et Am dans les amas ouverts (Edition révisée)
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The luminosity of reflection nebulae
Consideration is given to the connection between the dispersion inHubble's relation for reflection nebulae and their morphologicalcharacteristics. Statistical estimates show that the reflection nebulaeconnected with more opaque dust-gas clouds, compared to those near lessopaque clouds, have large values of Delta-B (the measure of deviationsin Hubble's relation) and a high surface brightness. These propertiesare more pronounced in the Herbig Ae/Be stars. Stars in the nebulaeconnected with more opaque dust-gas clouds were found to exhibit excessreddening, with R above 3.1. It is concluded that the dispersion in theHubble relation is mainly due to the optical depth of the nebulae.
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Catalog of AP and AM stars in open clusters
The previous results of Raab (1922), Markarian (1951), and Collinder(1931) have been used to catalog Ap and Am stars that are in the fieldof open clusters. Tabular data are presented for the clusterdesignation, the HD or HDE number, the right ascension (1900), thedeclination (1900), and the magnitude. Also listed are the spectraltypes and, for certain stars, the probability of cluster membership.
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Polarization of the light of the stars in the association MON R1
New observations of polarization of the light of the stars in thereflection nebula association Mon R1 are given. Of 17 stars investigatedin the B photometric system, nine are cores of reflection nebulas. Thestar VY Mon is found to have a large polarization. The manner in whichthe polarization of the stars and the structure of the nebulas arerelated to the magnetic field of the cloud in which they are situated isdiscussed.
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R associations. VI - The reddening law in dust clouds and the nature of early-type emission stars in nebulosity from a study of five associations
Positions, identification charts, UBVRIKLMN photometry and spectraltypes are given for stars, illuminating reflection nebulae that arevisible on the POSS prints, which have been identified in fiveassociations. With a ratio of total to selective extinction of 4.2, thereddening law applicable to the dust clouds in which the stars areembedded is steeper than normal. The five associations exhibit 18early-type stars with circumstellar shells, of which those with spectraltypes earlier than B5 characteristically have weak IR excesses, incontrast to the strong excesses indicative of circumstellar dust, oflater-type stars. Color-magnitude charts show a distribution lying abovethe ZAMS by up to about 2 mag for both the circumstellar shell stars andthose classified as rapid rotators. It is suggested that (1) rapidrotation accounts for the scatter in the color-magnitude diagram, and(2) many of the nebulous early-type emission-line stars are rapidrotators rather than pre-main sequence objects.
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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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The value of R in Monoceros
Recent photometric and spectroscopic observations are used inconjunction with other data for early-type stars in northern Monocerosin order to investigate the local value of R (the ratio of total toselective extinction). From a variable-extinction analysis, it isconcluded that a ratio of approximately 3.2 is appropriate for thegeneral interstellar extinction in this region and that there is noevidence here for the existence of local anomalies. The two majorassociations Mon OB 1 and Mon OB 2 are clearly delineated and are foundto exhibit properties typical of such young stellar groups. Derivedproperties for a few interesting stars are presented.
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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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Mesures d'étoiles doubles effectuées au réfracteur de 38 cm. de l'Observatoire de Nice
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