New Elements for 54 Eclipsing Binaries
This research presents new elements for 54 eclipsing binaries foundusing data from the ASAS-3, Hipparcos and NSVS databases. Some of thesystems studied are new and others are confirmed or had wrong elementsin the literature. The discovery of apsidal motion in TZ Pyx ispresented and an identification problem with CPD-41 7746 in NGC 6231 isaddressed. Conspicuous BE-variability superposed to eclipsing variationsis discovered in HD 61407.
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Main-sequence magnetic CP stars: II. Physical parameters and chemical composition of the atmosphere
This paper continues a series of reviews dedicated to magnetic CP stars.The occurrence frequency of CP stars among B5 F0-type main-sequencestars is shown to be equal to about 15 20%. The problems ofidentification and classification of these objects are addressed. Weprefer the classification of Preston, which subdivides chemicallypeculiar stars into the following groups: Am, λ Boo, Ap/Bp,Hg-Mn, He-weak, and He-strong stars. The main characteristic features ofobjects of each group are briefly analyzed. The rotation velocities ofCP stars are shown to be about three times lower than those of normalstars of the same spectral types (except for λ Boo and He-strongobjects). The rotation periods of CP stars range from 0.5 to 100 days,however, there is also a small group of objects with especially long (upto several tens of years) variability periods. All kinds of peculiarstars can be found in visual binaries, with Am-and Hg-Mn-type starsoccurring mostly in short-period binaries with P < 10 days, and thebinary rate of these stars is close to normal. The percentage ofbinaries among magnetic stars (20%) is lower than among normal stars. Arather large fraction of CP1-and CP2-type stars was found to occur inyoung clusters (with ages smaller than 107 years).Photometric and spectral variability of peculiar stars of various typesis discussed, and it is shown that only objects possessing magneticfields exhibit light and spectral variations. The chemical compositionof the atmospheres of CP stars of various types is considered. Theabundances of various elements are usually determined by comparing theline profiles in the observed spectrum with those of the syntheticspectra computed for various model atmospheres. Different mechanisms areshown to contribute to chemical inhomogeneity at the star’ssurface, and the hypothesis of selective diffusion of atoms in a stableatmosphere is developed. Attention is also paid to the problems of thedetermination of local chemical composition including the stratificationof elements. Some of the coolest SrCrEu peculiar stars are found toexhibit fast light variations with periods ranging from 6 to 15 min.These variations are unassociated with rotation, but are due tononradial pulsations. The final part of the the review considers thefundamental parameters of CP stars. The effective temperatures,luminosities, radii, and masses of these objects are shown to agree withthe corresponding physical parameters of normal main-sequence stars ofthe same spectral types.
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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
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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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A search for rapid oscillations in chemically peculiar A-type stars
In 1995 we initiated a Northern Hemisphere survey for rapidlyoscillating Ap stars. This paper presents the results including one newroAp star (HD 122970), the confirmation of rapid oscillations of HD99563 and apparent null results for other stars. Using Hipparcos data astatistical analysis of the absolute magnitudes and galacticdistributions of all known roAp and noAp stars (also taken from theliterature) was made. A systematic trend for most of the program starsin a M_{ V} vs. beta (index of the Strömgren uvbybeta system)diagram was detected leading to the conclusion that beta issystematically influenced by the chemical peculiarity and/or magneticfield. Three roAp stars are outside the delta Scuti instability stripwhich implies that the driving mechanism of the two classes of pulsatingstar is different. This is also suggested by new pulsation models. Nostatistical difference between the galactic distribution of roAp andnoAp stars was found.
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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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Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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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
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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.
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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.
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Objective-prism discoveries in the northern sky - II.
Five tables list the observed characteristics of 244 northern hemispherestars recorded in 100 108 A/mm dispersion plates at H-gamma wavelengths.The 5 x 5 deg fields contained a number of suspected weak-metal objects.Listings are divided into peculiar A stars, metallic line and deltaDelphini stars, high luminosity objects, Ca II emission stars of the Gand K type, and composite spectra.
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Lists of photometric AM candidates
The Geneva photometric m parameter (Nicolet and Cramer, 1982) is used inorder to select Am photometric candidates from the Rufener (1981)catalogue. Two lists are given, the first containing field stars and thesecond cluster stars. According to the photometric criteria thediffusion process probably responsible for the Am phenomenon takes placerather quickly as Am candidates are present in young clusters. It isconfirmed that the phenomenon is enhanced by low rotational velocity andhigh metallicity. The age seems to slightly affect the Am phenomenon.
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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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List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry
A list is presented of 333 stars, excluded from the GCVS and itssupplements, whose probability of variability ranges from high tocertain. The standard deviations observed in the V magnitude togetherwith the known spectral types, however, only allow speculation as to thetype of variable in question pending supplementary observations whichreveal the individual characteristics of these stars.
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Properties of AM stars in the Geneva photometric system
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....92..289H&db_key=AST
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UBVRI photometry of 225 AM stars
UBVRI photometry of 225 Am stars taken from Mendoza's (1974) catalog ispresented. The results are compared with those obtained by Feinstein(1974) for 21 of the stars and with the values of Johnson et al. (1966).It is assumed that in the first approximation the (V-I) color index ofan unreddened Am star is equal to that of a normal main-sequence star; astandard main sequence is defined for A and early F stars, and thefive-color photometry is analyzed by means of plots of U-V vs. V-I, B-Vvs. V-I, and V-R vs. V-I. Mean color deficiencies of Am stars areexamined, and it is suggested that an unreddened star located below themain-sequence A0-F2 line in the (V-I, U-V) plane is a photometric Amstar. It is concluded that: (1) photometric Am stars have colordeficiencies (as a function of V-I) which, on the average, are 0.07 magin (U-V) color index and 0.025 mag in (B-V) color index; (2) Am starswith V-R less than 0.25 mag may also have a color deficiency of about0.01 mag; (3) Am stars with V-R greater than 0.3 mag may have a colorexcess of approximately 0.01 mag; and (4) Am stars with V-R between 0.25and 0.3 mag may have normal colors.
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Multicolor photometry of metallic-line stars. III. A photometric catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974RMxAA...1..175M&db_key=AST
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Catalogue of AM stars with known spectral types
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&AS...10..385H&db_key=AST
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Observations spectrographiques d'etoiles A a spectre particulier et a raies metalliques.
Not Available
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Catalogue et bibliographie des étoiles A à spectre particulier - Deuxième supplément
Not Available
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Catalogue et bibliographie des étoiles A à spectre particulier Premier supplément
Not Available
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Catalogue et bibliographie des étoiles A à spectre particulier
Not Available
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