The DDO IVC Distance Project: Survey Description and the Distance to G139.6+47.6
We present a detailed analysis of the distance determination for oneintermediate-velocity cloud (IVC, G139.6+47.6) from the ongoing DDO IVCDistance Project. Stars along the line of sight to G139.6+47.6 areexamined for the presence of sodium absorption attributable to thecloud, and the distance bracket is established by astrometric andspectroscopic parallax measurements of demonstrated foreground andbackground stars. We detail our strategy regarding target selection,observational setup, and analysis of the data, including a discussion ofwavelength calibration and sky subtraction uncertainties. We find adistance estimate of 129+/-10 pc for the lower limit and257+211-33 pc for the upper limit. Given the highnumber of stars showing absorption due to this IVC, we also discuss thesmall-scale covering factor of the cloud and the likely significance ofnondetections for subsequent observations of this and other similarIVCs. Distance measurements of the remaining targets in the DDO IVCproject will be detailed in a companion paper.
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Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
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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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Behaviour of calcium abundance in Am-Fm stars with evolution
Calcium abundance in the atmosphere of Am stars is examined as afunction of their evolutionary state within the main sequence. Newspectroscopic abundances as well as abundances obtained photometricallyby Guthrie (1987) are used, since they are mutually quite consistent.The main result of this work is that, contrary to earlier suggestions,calcium abundance does not tend to be larger in evolved Am stars than inunevolved ones, for objects distributed along a given evolutionary trackin the HR diagram. The trend appears to be the reverse, if it is presentat all. For our whole sample of Am stars, there is a significantcorrelation between calcium abundance and effective temperature, in thesense that the cooler objects are the most Ca-deficient, hence have themost pronounced Am peculiarity. This implies an apparent correlationbetween calcium deficiency and age, although the lack of Am starsyounger than log t = 8.6 seems real. Our results are fully consistentwith the low rate of Am stars observed in young clusters and withtheoretical predictions of time-dependent radiative diffusion (Alecian1996). Based on observations collected at Observatoire de Haute Provence(CNRS), France, and on data from the ESA HIPPARCOS astrometry satellite.
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The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..135A&db_key=AST
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Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
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Abundances of calcium for a sample of 57 classical AM stars
Abundances of calcium, log N(Ca), are derived for a fairly completesample of 57 single-lined classical Am stars. Published photoelectricmeasures of the CaII K-line at 3933 A and K-line spectral types are usedto determine the equivalent widths of the K-line for a differentialcurve-of-growth comparison of the Am stars with the standard stars 15Vul and 28 And. On a scale with log N(H) = 12.0, the values of log N(Ca)for the Am stars range from 5.5 to 6.5, the solar value being 6.36. TheAm stars with low abundances of calcium have a small range of themodified age parameter, and absolute magnitudes within about 1.3 mag ofthe zero-age main sequence, whereas the other Am stars and normal starshave a larger spread in age. These results are probably consistent withthe suggestion that the Am phenomenon is due to subphotosphericseparation of elements by diffusion in slowly rotating A-type stars.
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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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UV photometric data on standard A, F and AM stars observed by S2/68
Data derived from the stellar UV fluxes of the S2/68 experiment andanalyzed and interpreted by Van't Veer et al. (1980) are presented.There are two tables of photometric data. One lists all standard stars,without exception, belonging to the intersection of the following threecatalogs: (1) the Thompson et al. (1978) catalog of S2/68 fluxes; (2)the PMR catalog (Philip et al., 1976), which is an analysis of theHauck-Mermilliod catalog (1975) of homogeneous four color data; and (3)the Crawford and Barnes (1970) list of standard stars for uvbyphotometry. The other table lists all the Am stars, without exception,belonging to the intersection of the following three catalogs: (1)Thompson et al. (1978); (2) PMR (1976); and (3) the Hauck (1973) catalogof the Am stars.
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The absolute magnitude of the AM stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&A....93..155G&db_key=AST
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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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Spectral classification of stars with the same colours in intermediate multiband photometry - The concept of photometric 'star-box'
The concept of a photometric 'star box' is introduced for use with the UB V B1 B2 V1 G photometric system. Star boxes are employed to grouptogether all stars for which each photometric color differs by less thansome small quantity (in magnitude) from the corresponding color of agiven 'central' star. Probable causes of differences between the colorsof two stars are summarized, scatter in spectral type and luminosityclass within a single box is discussed, and the standard deviation ofnarrow-band photometric indices is calculated for stars grouped in thesame box. Dispersions in the UV and IR energy distributions of stars inthe same box are examined, and the results obtained in the seven-colorphotometric system for 113 stars are compared with the correspondingresults in a thirteen-color system. The classification of Am and Am:stars is briefly examined on the basis of star boxes.
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Absolute luminosity calibration of Stroemgren's 'late group'
A statistical parallax method based on the principle of maximumlikelihood is used to calibrate absolute luminosities for samples ofcooler stars constituting the 'late group' defined by Stromgren (1966).The samples examined include 415 stars of all luminosity classes and asubset comprising 86 main-sequence stars. Linear calibration relationsinvolving the Stromgren beta, (b-y), and bracketted c1 indices arederived which yield mean absolute magnitudes with an accuracy of 0.09magnitude for the overall sample and 0.13 magnitude for themain-sequence subsample. Several second-order relations are considered,and the results are compared with Crawford's (1975) calibrations as wellas with mean absolute magnitudes obtained from trigonometric parallaxes.The possible effect of interstellar absorption on the calibrationrelations is also investigated.
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Bright metallic-line and pulsating A stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976PASP...88..402E&db_key=AST
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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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UVBY photometry of AM and AP stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973AJ.....78..192W&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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Four-color and Hβ photometry for the brighter AO type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....5..109C&db_key=AST
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Observations of the 21-CM Hydrogen Line Toward High-Latitude Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157.1101G&db_key=AST
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List of newly identified matallic line A stars
Not Available
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INHABITED SKY
