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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Searching for links between magnetic fields and stellar evolution: II. The evolution of magnetic fields as revealed by observations of Ap stars in open clusters and associations
Context: The evolution of magnetic fields in Ap stars during the mainsequence phase is presently mostly unconstrained by observation becauseof the difficulty of assigning accurate ages to known field Ap stars. Aims: We are carrying out a large survey of magnetic fields in clusterAp stars with the goal of obtaining a sample of these stars withwell-determined ages. In this paper we analyse the information availablefrom the survey as it currently stands. Methods: We select from theavailable observational sample the stars that are probably (1) clusteror association members and (2) magnetic Ap stars. For the stars in thissubsample we determine the fundamental parameters T{eff},L/L_ȯ, and M/M_ȯ. With these data and the cluster ages weassign both absolute age and fractional age (the fraction of the mainsequence lifetime completed). For this purpose we have derived newbolometric corrections for Ap stars. Results: Magnetic fields arepresent at the surfaces of Ap stars from the ZAMS to the TAMS.Statistically for the stars with M > 3 M_ȯ the fields declinewith advancing age approximately as expected from flux conservationtogether with increased stellar radius, or perhaps even faster than thisrate, on a time scale of about 3×107 yr. In contrast,lower mass stars show no compelling evidence for field decrease even ona timescale of several times 108 yr. Conclusions: Study ofmagnetic cluster stars is now a powerful tool for obtaining constraintson evolution of Ap stars through the main sequence. Enlarging the sampleof known cluster magnetic stars, and obtaining more precise rms fields,will help to clarify the results obtained so far. Further fieldobservations are in progress.Tables 2 and 3 are only available in electronic form athttp://www.aanda.org
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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Searching for links between magnetic fields and stellar evolution. I. A survey of magnetic fields in open cluster A- and B-type stars with FORS1
Context: .About 5% of upper main sequence stars are permeated by astrong magnetic field, the origin of which is still matter of debate. Aims: . With this work we provide observational material to studyhow magnetic fields change with the evolution of stars on the mainsequence, and to constrain theory explaining the presence of magneticfields in A and B-type stars. Methods: . Using FORS1 inspectropolarimetric mode at the ESO VLT, we have carried out a survey ofmagnetic fields in early-type stars belonging to open clusters andassociations of various ages. Results: . We have measured themagnetic field of 235 early-type stars with a typical uncertainty of 100 G. In our sample, 97 stars are Ap or Bp stars. For thesetargets, the median error bar of our field measurements was 80 G.A field has been detected in about 41 of these stars, 37 of which werenot previously known as magnetic stars. For the 138 normal A and B-typestars, the median error bar was 136 G, and no field was detected in anyof them.
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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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Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Deep Hα survey of the Milky Way. III. The l=338deg area.
The Galactic plane has been observed between l=337deg and l=342deg inthe frame of an Hα Survey of the Southern Milky Way. This area isknown to be rich in radio sources but poor in Hα emission. Theanalysis of high resolution profiles of the Hα emission observedin this direction nevertheless enabled to distinguish 6 differentvelocity components: 2 faint layers of diffuse ionized hydrogen at 0 and-12km/s (V_LSR_), 2 brighter layers at -28 and -39km/s includingindividual HII regions, a faint patch at -50km/s and two isolated brightHII regions at -61km/s. Combining these Hα observations withstellar and radio data we conclude about the most probable distances forthe different components.
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Stromgren and H beta photometry of OB associations and open clusters. I - ARA OB1
Stromgren and H beta photometry of 38 stars in the field of Ara OB1 ispresented. The excesses, the absolute magnitudes and the temperatures ofthe stars have been obtained. The masses and the ages are alsoestimated, based on the models of Maeder and Meynet. Two differentgroups have been distinguished by their space locations at V0 - MV =10.23 and 12.01 mag (assuming a normal extinction law). The more distantgroup is younger and more massive. The magnitude and the excess of theWR star MR62 point to its probable membership of this group. There aregood reasons to suspect a value of the total-to-selective absorptionratio that is greater than the normal 3.2, which leads to a significantreduction of the true distance moduli.
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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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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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NGC 6240 - A unique interacting galaxy
It is demonstrated that the nucleus of the radio galaxy NGC 6240consists of two components. A pronounced double nucleus has beendetected on an S 1 image tube plate in the I band and on r and Iexposures of the galaxy taken with a CCD camera. CCD photometry resultsfor the two nuclei and for the galaxy as a whole are shown, along withisophote-plots of the CCD exposures and spectra of the galaxy. Imagetube spectrograms provide evidence that the extended regions of ionizedgas in the galaxy are dominated by shock heating on a scale of about 6kpc. The morphology of the galaxy is discussed, emphasizing thesimilarity of the two nuclei as evidence that two colliding galaxies areinvolved.
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Analysis of the results of MK classification of 176 stars in 37 southern open clusters
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979A&AS...37..345F&db_key=AST
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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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Southern open stars clusters. III. UBV-Hbeta photometry of 28 clusters between galactic longitudes 297d and 353d
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&AS...10..135M&db_key=AST
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An association of O and B stars in Ara
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963MNRAS.125..105W&db_key=AST
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