The Naini Tal - Cape survey for pulsations in chemically peculiar A-type stars. I. Methods and preliminary results
A new survey for pulsating, chemically peculiar A- and F-type stars inthe northern hemisphere has been initiated using the 1-m telescope atUttar Pradesh State Observatory in Naini Tal. The survey is primarilystructured to reveal high-overtone pulsations in chemically peculiar A-Fstars, but it is also revealing low-overtone delta Scuti-type pulsationsin stars with peculiar colours. This paper describes the scope andmethods of the survey. Preliminary observations of 28 candidate starsare presented and the discovery of three new pulsators, HD 12098, HD13038 and HD 13079, is announced. Null results for the remaining 25stars are also discussed.
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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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Statistical Investigation of Chemically Peculiar Stars - Part Two - the Stars with the Dispersion of Continuum Spectrum at Lambda 5200A
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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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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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Uvbyg1g2-photometry of some fainter Ap-stars
uvbyg1g2 photometry (Maitzen, 1976) in a slightly modified system ispresented and its performance compared with previous photometry. Theresulting peculiarity parameter values Delta a are compared withpublished Geneva system Delta (V1-G) values. As two stars of the sampleare markedly reddened the problem of dereddening (b-y) for Ap stars hadto be discussed. Reddening corrected Delta a values were obtained.
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Photometric parameters for AM and AP stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&A....69..285H&db_key=AST
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Ultraviolet photometric observations of AP and AM stars
ANS five color ultraviolet photometric observations of 79 hot and coolAp stars and 26 Am stars are presented. The positions of Ap and Am starsin ultraviolet color-color diagrams differ from those of normalmain-sequence stars of the same spectral type. The deviation is largestfor the cooler Ap stars. The ultraviolet flux deficiency known to existfor the hot (early type) Ap stars appears to decrease towards laterspectral types and is absent for the Am stars. The light variable HR5857 shows ultraviolet light variations of which the amplitude graduallydecreases towards longer wavelengths.
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Catalogue of early-type stars measured in a narrow-band photometric system
A compilation of the photoelectric measurements in the Barbier-Morguleffsystem is presented. The catalogue includes data for 773 stars ofspectral type 08 to F6. 706 stars have been measured at least twice.
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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.
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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 Premier supplément
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Catalogue et bibliographie des étoiles A à spectre particulier
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Magnetic Fields of the A-Type Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958ApJ...128..228B&db_key=AST
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A Catalog of Magnetic Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958ApJS....3..141B&db_key=AST
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INHABITED SKY
