uvby FCAPT Photometry of Six Small-Amplitude mCP Stars
If magnetic fields cause elemental abundances to change in the stellarphotosphere, then all magnetic chemically peculiar (mCP) stars shouldexhibit signatures of this effect in both their spectra and fluxdistributions. Given that all stars rotate, these stars should bemagnetic, spectrum, and photometric variables, albeit sometimes of lowamplitude. We study differential Strömgren observations from theFour College Automated Photoelectric Telescope (FCAPT) of α Psc,HR 5857, and HR 6709, which are small-amplitude mCP stars, and AB Cet,HD 15890, and HR 8240, which were thought to be near-constant mCP stars,to determine the periods and amplitudes of their photometricvariability. We construct the photometric amplitude distributionfunctions of the mCP stars studied by the first author to obtainstatistics on their photometric variability in Strömgrenphotometry. The star α Psc has a period of 0.74552 days, with itslargest amplitude in u of 0.030 mag. The largest amplitude (0.035 mag)for HR 5857 is also for u. We confirmed the period of 1.29957 days foundby Hatzes using Doppler imaging. For HR 6709 the largest amplitudeobserved (0.010 mag) is for u photometry. Its period is 1.20352 days. ABCet might be minimally variable. HD 15980 appears to be minimallyvariable, with a period of at least 5 yr. HR 8240 is variable with a bamplitude about 0.05 mag and a period that is several years long.Additional observations of these six stars would be useful to confirmtheir characteristics. Two apparently constant stars studied with FCAPTStrömgren data, HD 11187 and HD 50169, should be checked to seewhether they are long-period variables. If additional observations showtheir variability, then all mCP stars observed photometrically by thefirst author with the FCAPT will be found to be variable.
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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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uvby FCAPT Photometry of the Magnetic Chemically Peculiar Stars 36 Aurigae, HR 2722, 13 Andromedae, and HD 220147
Differential Strömgren uvby observations obtained with the FourCollege Automated Photoelectric Telescope (FCAPT) are presented for themagnetic chemically peculiar (mCP) stars 36 Aur, HR 2722, 13 And, and HD220147. The new data help to better define the light curves. The periodfor 36 Aur was found to be 14.368 days, close to that for the previousstudy with FCAPT data. The period for HR 2722 is unchanged, at 2.31523days. Comparisons between Hipparcos and FCAPT photometry were used torefine the periods individually derived by each source to 1.47931 daysfor 13 And and to 10.983 days for HD 220147.
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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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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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New variable chemically peculiar stars identified in the HIPPARCOS archive
Since variability of chemically peculiar (CP) stars plays an importantrole for the astrophysical explanation of their outstanding behaviour,we have identified new variable CP stars listed in Renson's catalogueusing the extensive Hipparcos Variability Annex. From the 293 objectsfound, 33 were excluded because they are no CP stars and/or have noperiod listed, half of the remaining stars are newly identified and halfhad been already included in the catalogue of variable CP stars by\cite[Catalano & Renson (1997).]{Ca} Most of the newly identifiedvariability is due to an apparent magnetic field coupled with stellarrotation (oblique rotator model). The constraints of this model arefulfilled for all but three CP2 stars. Variations of bona fide Am-Fmstars are exclusively explained by eclipses of binary systems.Furthermore eight candidates of the >~mma Doradus group (pulsatingAm-Fm stars) were detected. Based on data from the ESA Hipparcosastrometry satellite. Table 1 is also available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia\break http://cdsweb.u-strasbg.fr/Abstract.html
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On the HIPPARCOS photometry of chemically peculiar B, A, and F stars
The Hipparcos photometry of the Chemically Peculiar main sequence B, A,and F stars is examined for variability. Some non-magnetic CP stars,Mercury-Manganese and metallic-line stars, which according to canonicalwisdom should not be variable, may be variable and are identified forfurther study. Some potentially important magnetic CP stars are noted.Tables 1, 2, and 3 are available only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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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 list of effective temperatures of chemically peculiar stars. II.
Not Available
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Spectrophotometry of Peculiar B-Stars and A-Stars - Part Nineteen - Variability of the Magnetic Cp-Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..101..393A&db_key=AST
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New peculiar stars identified on objective-prism plates
Tables are presented of 90 peculiar stars revealed on more than oneobjective-prism plate and 61 suspected peculiar stars based on a singlespectrum. The set of 90 peculiar stars includes 48 Ap, 32 Am, and 10stars with composite spectra. The stars were identified as peculiarstars during spectral classification in the regions of the OBassociations Cyg OB4, Cep-Lac OB1, and Cas OB9. The spectralcharacteristics of the different types of peculiar stars are discussed.
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Balmer Discontinuities of Chemically Peculiar Stars
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On the Effective Temperatures of Chemically Peculiar Stars
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Statistical Investigation of Chemically Peculiar Stars - Part Two - the Stars with the Dispersion of Continuum Spectrum at Lambda 5200A
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Visual multiples. VIII - 1000 MK types
A total of 1000 new classifications are given for stars brighter than B= 8.0 mag in the Aitken double star catalog. The classificationssupplement 865 classifications obtained in 1981 and 1984. Among thenewly discovered stars are 12 new Ap stars, eight Lambda Bootis stars,one Ba II star, and 60 Am stars. A detailed list of the newclassifications is given.
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Evidence of decay of the magnetic fields of AP stars
Data obtained in the Geneva photometric system (Rufener, 1981) andappropriate calibrations of this system in terms of surface magneticfield and gravity are used to provide, on the basis of 708 field andcluster Ap stars, observational evidence that these stars undergo decayof their magnetic field on an evolutionary timescale. Justifications aregiven for the application of a photometric gravity calibration topeculiar stars. The dependence of the photometrically estimated surfacemagnetic field on gravity is found to differ markedly from availabletheoretical calculations. HgMn stars are found to show the same trend,strengthening the impression that they might be slightly magnetic.He-weak stars do not.
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Photometric properties of AP stars in the Geneva system
An examination of the properties in some photometric diagrams of morethan 600 Ap stars measured in the Geneva photometric system confirm thatthe Balmer discontinuity is smaller than for normal stars, along withthe link between a proposed peculiarity parameter and both rotationalvelocity and effective magnetic field. It is shown that the peculiarityparameter is sensitive to interstellar reddening, and it is foundthrough examination of the standard deviations for visual magnitudesthat cool CP 2 stars without Eu peculiarity have the greatestamplitudes. Rapid rotators have a mild peculiarity, while positivecorrelation exists for Si and SrCr stars.
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Spectrophotometry of peculiar B and A stars. VII - HD 6164, HD 8855, HD 11187, HD 171782, HD 190068, HD 200311, and HD 220147
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...42..375A&db_key=AST
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Catalogue of photometric data related to surface magnetic fields for B-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...41..111C&db_key=AST
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Spectrophotometry of peculiar B and A stars. I - On the detection of the lambda 4200 and lambda 5200 broad, continuum features of peculiar A stars
Photometric indices are used to study the broad continuum features thatare present in the energy distributions of many peculiar A stars andthat may be indicators of the atmospheric structure. Indices derivedfrom representative or averages of spectrophotometric scans areconsidered. Values of Maitzen's (1976) delta-a index - a measure of thelambda 5200 feature - are synthetized from spectrophotometric data. Twoother specific indices are calculated from spectrophotometry to measurethe strength of lambda 4200 feature. The details of the photometricvariability are presented with the data. Possible effects of thevariability on the conclusions made are discussed.
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New peculiar stars.
Not Available
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A photoelectric parameter of the peculiarity of the AP stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...26...49H&db_key=AST
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Observations spectrographiques d'etoiles A a spectre particulier et a raies metalliques.
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Absolute Emission Line Intensities of Planetary Nebulae. II.
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Catalogue et bibliographie des étoiles A à spectre particulier - Deuxième supplément
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Catalogue et bibliographie des étoiles A à spectre particulier
Not Available
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Anomalous Spectra of Stars of Class a.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1949ApJ...110...67W&db_key=AST
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