The Period Changes of Polaris
The evolutionary changes in pulsation period for the Cepheid Polaris arereinvestigated using archival observational material (radial velocities,photometry, and eye observations) over the interval 1844 to the present,including new photometry for the star obtained in 2003-2004. The star'spulsation period increased at a rate of 4.5 s yr-1 duringthat interval, with the exception of a brief hiatus between 1963 and1966, when it suddenly decreased, possibly as a result of a briefreduction in average stellar radius amounting to -0.055%. At roughly thesame time, the pulsation amplitude of Polaris underwent a marked change.Prior to 1963 the V amplitude was in excess of about 0.1 mag, possiblydecreasing at a rate of 0.019 mag century-1. Following thehiatus of 1963-1966, the pulsation amplitude underwent a sharp declineand now appears to be erratic on a cycle-to-cycle basis, always smallerthan 0.05 mag. The rapid rate of period increase for Polaris isconsistent with a first crossing of the Cepheid instability strip, whilethe hiatus of 1963-1966 and sudden decrease in pulsation amplitudethereafter suggest that the star may have left the instability strip forfirst crossers at that time, leaving it near the center of theinstability strip for Cepheids in higher crossing modes.
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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
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Optical images of MCLD123.5+24.9: a cloud illuminated by the North star?
We present B R I images of a 1degr {x}1degr field centered on themolecular cloud (MCLD123.5+24.9) located in the large infrared cirrusknown as the Polaris Flare. The optical images are compared with IRASimages and an extinction map derived from stellar reddenings. We analysethe possibility for the North star (HD8890), only 1degr North of thefield, to be the source of MCLD123.5+24.9 optical emission. For widelyaccepted values of the dust albedo (omega = 0.6) and the assymetryparameter of the Henyey Greenstein phase function (0.7
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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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Goodbye to Polaris the Cepheid
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993ApJ...416..820F&db_key=AST
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Fifth fundamental catalogue. Part 2: The FK5 extension - new fundamental stars
The mean positions and proper motions for 3117 new fundamental starsessentially in the magnitude range about 4.5 to 9.5 are given in thisFK5 extension. Mean apparent visual magnitude is 7.2 and is on average2.5 magnitudes fainter then the basic FK5 which has a mean magnitude of4.7. (The basic FK5 gives the mean positions and proper motions for theclassical 1535 fundamental stars). The following are discussed: theobservational material, reduction of observations, star selection, andthe system for the FK5 extension. An explanation and description of thecatalog are given. The catalog of 3117 fundamental stars for the equinoxand epoch J2000.0 and B1950.0 is presented. The parallaxes and radialvelocities for 22 extension stars with large forecasting effects aregiven. Catalogs used in the compilation of the FK5 fundamental catalogare listed.
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UBV photometry of stars whose positions are accurately known. VI
Results are presented from UBV photometric observations of 1000 stars ofthe Bright Star Catalogue and the faint extension of the FK5.Observations were carried out between July 1987 and December 1990 withthe 40-cm Cassegrain telescope of the Kvistaberg Observatory.
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A. de Sitter's photographic polar photometry revisited; some remarks on photographic photometry with objective gratings
Not Available
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Period and amplitude variations of Polaris
New photometric and radial velocity observations of Polaris arepresented. It is shown that a reinterpretation of the photometric O-Cresiduals as listed by Petrov (1949) can bring the photometric andradial velocity observations into agreement. The results suggest thatthe period of Polaris has been increasing for the past 100 years.Secular light amplitude changes in Polaris have been found whichstrongly suggest that the amplitude of the variation started to declineapproximately in 1945 and has been decreasing until the present.
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Final catalogue of 229 photometric standards in UBV system near the selected areas 1-115
Not Available
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The reddening of Polaris
The B-V color excess of Polaris is obtained by using uvby-betaphotometry of 11 field stars within 0.75 deg of arc of Polaris anddereddening the field stars with the various color calibrations of theStromgren system. An apparent distance of 109 pc is estimated forPolaris, and a color excess of E(B-V) equals 0.02 + or - 0.02 is found.This result is taken as supporting the claims that Polaris is unreddenedor at worst very slightly reddened and therefore lies on the red edge ofthe Cepheid instability strip, as is expected for a small-amplitudeCepheid.
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The corrected magnitudes and colours of 278 stars near S.A. 1-139 in the UBV system
Not Available
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Six-color photometry of stars. VIII. The colors of 409 stars of different spectral types
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJ...123..440S&db_key=AST
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A photometric system
Not Available
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Sur la détermination de la grandeur de la discontinuité de Balmer par les méthodes de la photométrie à travers des filtres
Not Available
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Photoelectric Studies. VII. Color and Magnitude Systems for Brighter Stars and the Color-Spectral Relation.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...113..663E&db_key=AST
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The Color-Magnitude Array for Stars in the Globular Cluster M 15.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...113..344B&db_key=AST
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Red and Infrared Magnitudes for 125 Stars in Ten Areas
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...113..324K&db_key=AST
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Photoelectric Studies. I. Color-Luminosity Array for Members of the Hyades Cluster.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1950ApJ...111...65E&db_key=AST
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Photographic magnitudes of stars brighter than 7m.75 between +75° and +80° declination (Errata: 11 270)
Not Available
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Yerkes actinometry. Zone +73deg to +90deg.
Not Available
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INHABITED SKY
