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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).
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars
This paper presents the catalogue and the method of determination ofaveraged quadratic effective magnetic fields < B_e > for 596 mainsequence and giant stars. The catalogue is based on measurements of thestellar effective (or mean longitudinal) magnetic field strengths B_e,which were compiled from the existing literature.We analysed the properties of 352 chemically peculiar A and B stars inthe catalogue, including Am, ApSi, He-weak, He-rich, HgMn, ApSrCrEu, andall ApSr type stars. We have found that the number distribution of allchemically peculiar (CP) stars vs. averaged magnetic field strength isdescribed by a decreasing exponential function. Relations of this typehold also for stars of all the analysed subclasses of chemicalpeculiarity. The exponential form of the above distribution function canbreak down below about 100 G, the latter value representingapproximately the resolution of our analysis for A type stars.Table A.1 and its references are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/407/631 and Tables 3 to 9are only available in electronic form at http://www.edpsciences.org
| Multiplicity among chemically peculiar stars. II. Cool magnetic Ap stars
We present new orbits for sixteen Ap spectroscopic binaries, four ofwhich might in fact be Am stars, and give their orbital elements. Fourof them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. Thetwelve other stars are: HD 9996, HD 12288, HD 40711, HD 54908, HD 65339,HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 and HD216533. Rough estimates of the individual masses of the components of HD65339 (53 Cam) are given, combining our radial velocities with theresults of speckle interferometry and with Hipparcos parallaxes.Considering the mass functions of 74 spectroscopic binaries from thiswork and from the literature, we conclude that the distribution of themass ratio is the same for cool Ap stars and for normal G dwarfs.Therefore, the only differences between binaries with normal stars andthose hosting an Ap star lie in the period distribution: except for thecase of HD 200405, all orbital periods are longer than (or equal to) 3days. A consequence of this peculiar distribution is a deficit of nulleccentricities. There is no indication that the secondary has a specialnature, like e.g. a white dwarf. Based on observations collected at theObservatoire de Haute-Provence (CNRS), France.Tables 1 to 3 are 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/394/151Appendix B is only available in electronic form athttp://www.edpsciences.org
| 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
| 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
| 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
| A catalogue of [Fe/H] determinations: 1996 edition
A fifth Edition of the Catalogue of [Fe/H] determinations is presentedherewith. It contains 5946 determinations for 3247 stars, including 751stars in 84 associations, clusters or galaxies. The literature iscomplete up to December 1995. The 700 bibliographical referencescorrespond to [Fe/H] determinations obtained from high resolutionspectroscopic observations and detailed analyses, most of them carriedout with the help of model-atmospheres. The Catalogue is made up ofthree formatted files: File 1: field stars, File 2: stars in galacticassociations and clusters, and stars in SMC, LMC, M33, File 3: numberedlist of bibliographical references The three files are only available inelectronic form at the Centre de Donnees Stellaires in Strasbourg, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The Cape rapidly oscillating AP star survey - III. Null results of searches for high-overtone pulsation.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994MNRAS.271..129M&db_key=AST
| Stratification of helium in the photopsheres of the helium-weak stars HD 28843 and HD 49333
For four helium-weak and variable B stars phase-dependenthigh-resolution spectrograms have been obtained with theEchelec-spectrograph attached to the 1.5 European Southern Observatory(ESO) telescope, with the aim of testing whether He I 4471A will giveevidence of chemical stratification within their photospheres. Of thefour candidates, HR 3448 = HD 74196 is a fast rotator (v sin i=300km/s), however, no variability is detectable, while HR 1100=HD 22470does not exhibit any helium line (possibly due to incomplete phasecoverage). Only HR 1441=HD 28843 and HR 2509=HD 49333 are genuine heliumvariables. Profile analyses of He I 4471, based on fully line blanketedmodel atmospheres which are adapted to the relevant helium-content showthat HD 28843 can fully be explained by a cap model with twoasymmetrically located helium caps of equal radii. For HD 49333 verticalstratification in addition has to be assumed in order to explain theexcessively broad wings. This confirms earlier (preliminary) results byGroote et al. (see Hunger 1986). Vertical stratification is infered forboth inside and outside the helium-caps of HD 49333.
| Catalogue of CP stars with references to short time scale variability
A catalogue was compiled which contains all references in the literaturesince 1962 related to variations of CP stars on time scales shorter thanthe rotation period. The role of this catalogue lies in the unbiasedlisting of all available references, and not in a critical evaluation.
| Detection of calcium abundance stratification in AP stars
Very recent observational and theoretical studies have shown that anabundance stratification of chemical elements seems to be present in theatmosphere of the Ap SrCrEu star 53 Cam. This is fundamental for ourunderstanding of the structure and the stability of the stellaratmosphere of magnetic stars. In contrast with previous work from theauthor which were devoted to an intensive study of 53 Cam, the purposeof the present paper is to investigate abundance stratification in asmaple of 28 Ap stars, mainly of the SrCrEu type. From the analysis ofthe well-known peculiar profile of the Ca II K line these objects andfrom a differential analysis using the Ca II H line, we obtain that alarge Ca abundance stratification seems to be present in all the Apstars with Teff less than 9000 K. For hotter objects, themethod used in this paper does not permit to conclude. This analysissupports strongly the conclusions from the diffusion model and gives newconstraints on hydrodynamical processes in the photosphere of Ap stars.It constitutes the first evidence for a symmetric abundancestratification of Ca in a large sample of magnetic stars.
| A new list of effective temperatures of chemically peculiar stars. II.
Not Available
| 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
| A seven-year northern sky survey of AP stars for rapid variability
A high-speed photometric survey of 120 Ap stars in the northern sky, hasbeen conducted, between 1985 and 1991, in order to search for rapidvariability. Stars of spectral types, namely from B8 to F4, have beenselected for the survey. The selected pulsational variable stars occupythe hotter regions of the instability strip of the Hertzsprung-Russeldiagram. Noted is the absence of pulsations in the hotter B8-A3 Apstars; this does not, however, preclude the existence of pulsations,since HD 218495 was recently discovered to be a rapidly oscillating Ap(roAp) star. The primary result of this study is that variouscombinations of photometric indices, while pointing towards roAp starshaving the characteristic signatures of cool, SrCrEu stars, still failto isolate the roAp phenomenon from similar nonpulsating Ap stars.Color-magnitude and color-color diagrams are presented in order tocomplete this survey.
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
| Looking for rapidly-oscillating AP stars in the Northern Hemisphere
Several northern Ap stars have been monitored to search for short-period(P less than 15 min) photometric variations. It was not possible toconfirm the low-amplitude variability of HR 2977 and HR 5156 reported byMatthews and Wehlau (1985). HR 5747 was observed near magnetic maximum;it showed no sign of rapid variations. No evidence of variability wasfound in HD 165474, HD 188471, and HD 191742 over several days ofobservation. Of the seven Ap stars observed, only HR 7167 (10 Aql)showed evidence of rapid light variability, with a period of 11.4minutes and a peak-to-peak B amplitude of about 0.55 mmag. Thisdetection is considered only tentative; further observations are neededto confirm the variability of HR 7167.
| Balmer Discontinuities of Chemically Peculiar Stars
Not Available
| The Magnetic Fields and another Parameters of the Chemically Peculiar Stars - Part One
Not Available
| On the Effective Temperatures of Chemically Peculiar Stars
Not Available
| Statistical Investigation of Chemically Peculiar Stars - Part Two - the Stars with the Dispersion of Continuum Spectrum at Lambda 5200A
Not Available
| A catalogue of Fe/H determinations, 1984 edition
The present version of the Cayrel de Strobel et al. (1981) catalog ofFe/H abundance ratio determinations contains 1921 values for 1035 stars,which represents an augmentation over the previous publication of 48 and47 percent, respectively. In addition, the literature search conductedis complete up to December, 1983. Stellar metal abundance, effectivetemperature, spectroscopic gravity, spectral type, and photometricindices are covered.
| 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.
| Calcium in the atmospheres of peculiar stars
Data on the calcium content in the atmospheres of peculiar stars,obtained with model atmospheres and from literature sources, areanalyzed. The Ca I and Ca II spectra in Ap stars are studied. It isshown that the equivalent widths of Ca II K lines in the spectra of Apstars correspond on the average to their color indices B - V, although alarger scatter is observed than for normal stars. The conclusion thatthe calcium content in the atmospheres of Ap stars is normal on theaverage is drawn on the basis of an analysis of the effectivetemperatures used to find the calcium content, the methods ofdetermining the content, and the accuracy in measuring the equivalentwidths of Ca I and Ca II lines. The strengthening and weakening of theintensity of the Ca II K line in the spectra of peculiar stars are mostlikely explained by the difference in the structures of the atmospheresof Ap stars from normal.
| Spectrophotometry of peculiar B and A stars. XI - HD 89069, HD 165474, 10 Aquilae, HD 191742, HD 192678, and HD 204411
Optical region spectrophotometry at 3300-7100 A is presented for sixvery sharp-lined peculiar A stars, HD 89069, HD 165474, 10 Aquilae, HD191742, HD 192678, and HD 204411. Evidence is given concerning thepossible variability of these stars, especially HD 89069 and HD 192678.Deviations from the predictions of normal stellar atmospheres arediscussed.
| Radiative forces and the abundance of calcium and strontium in Ap-Bp stars
A diffusion model explaining the calcium and strontium abundanceanomalies in Hg-Mn and magnetic Ap stars is presented. Radiativeacceleration calculations are performed, and the effects of linesaturation and UV blanketing are discussed. In the Hg-Mn stars, theradiative acceleration on calcium and strontium decreases below gravityin the high photosphere. Both elements remain bound to the star even inthe absence of a magnetic field. The equilibrium distributions for bothelements are obtained, and the equivalent widths are derived using thenonuniform distribution. It is shown that the effect of the magneticfield in Ap stars on the radiative forces and equivalent line widths issignificant.
| Analysis of one characteristic of AP stars - The depression at 5200 A
The paper examines the structure of the broad-band flux depression at5200 A, characteristic of Ap stars, using a three-filter photometricsystem with intermediate-band filters at 5000 A, 5220 A, and 5400 A.With use of the three filters, the strength of the depression ismeasured, obtaining the Ap parameter, delta a, which quantifies thisdepression. The depression is analyzed in a manner similar to that usedby Maitzen and Seggewiss (1980) and the results from these two analysesare compared. The present results are in disagreement with theirconclusion that the depression at 5200 A is composed of two maincomponents having different tempe58ture behavior. Instead the resultsshow a continuous variation of Ap parameters with temperature.
| A photometric way to the surface magnetic field of AP stars
It is shown that a definite relation exists between photometricparameters of peculiarity and surface magnetic fields of slowly rotatingSr Cr Eu stars. The effect of binarity is discussed and it is shown thatthe above relation does not hold for the coolest Ap stars.
| 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.
| 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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Observation and Astrometry data
| Constellation: | Schwan |
| Right ascension: | 20h09m47.04s |
| Declination: | +42°32'28.8" |
| Apparent magnitude: | 8.16 |
| Distance: | 355.872 parsecs |
| Proper motion RA: | 10.3 |
| Proper motion Dec: | -0.5 |
| B-T magnitude: | 8.426 |
| V-T magnitude: | 8.182 |
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INHABITED SKY
