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A photometric study of chemically peculiar stars with the STEREO satellites - I. Magnetic chemically peculiar stars
About 10 per cent of upper main-sequence stars are characterized by thepresence of chemical peculiarities, often found together with astructured magnetic field. The atmospheres of most of those chemicallypeculiar stars present surface spots, leading to photometric variabilitycaused by rotational modulation. The study of the light curves of thosestars therefore permits a precise measurement of their rotationalperiod, which is important to study stellar evolution and to planfurther detailed observations. We analysed the light curves of 1028chemically peculiar stars obtained with the STEREO spacecraft. Wepresent here the results obtained for the 337 magnetic chemicallypeculiar stars in our sample. Thanks to the cadence and stability of thephotometry, STEREO data are perfectly suitable to study variabilitysignals with a periodicity typical of magnetic chemically peculiarstars. Using a matched filter algorithm and then two different periodsearching algorithms, we compiled a list of 82 magnetic chemicallypeculiar stars for which we measured a reliable rotational period; for48 of them, this is the first measurement of their rotational period.The remaining 255 stars are likely to be constant, although we cannotexclude the presence of long-period variability. In some cases, thepresence of blending or systematic effects prevented us from detectingany reliable variability and in those cases we classified the star asconstant. For each star we classified as variable, we determinedtemperature, luminosity, mass and fractional age, but the limitedstatistics, biased towards the shorter periods, prevented us fromfinding any evolutionary trend of the rotational period. For a fewstars, the comparison between their projected rotational velocity andequatorial velocity let us believe that their real rotational periodmight be longer than that found here and previously obtained. For the 82stars identified as variable, we give all necessary information neededto plan further phase-dependent observations. Data obtained with theHeliospheric Imager instruments on board the STEREO spacecraft.
| Catalogue of Ap, HgMn and Am stars
We present a catalogue of 8205 known or suspected Ap, HgMn and Am stars.This paper is a major update of our first edition of the catalog of Apand Am stars and includes revised identifications, additional stars andrevised information obtained from the literature.Catalogue (full Table 1) is only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/498/961
| Speckle Interferometry at the US Naval Observatory. XIII.
The results of 1424 speckle interferometric observations of doublestars, made with the 26 inch (66 cm) refractor of the US NavalObservatory, are presented. Each speckle interferometric observation ofa system represents a combination of over 2000 short-exposure images.These observations are averaged into 1053 mean relative positions andrange in separation from 0.36″ to 61.92″, with a medianseparation of 10.31″. This is the 13th in a series of paperspresenting measurements obtained with this system and covers the period2006 January 12-December 29. Included in these data are nine oldermeasurements whose positions were previously deemed possibly aberrantbut are no longer classified this way following a confirmingobservation. This paper also includes the first data obtained using anew "secondary" camera, designed and built at USNO.
| 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.
| General catalogue of AP and AM stars
A catalog of all the known Ap and Am stars, containing a total of 6684objects, was prepared. The few stars that were wrongly considered as Apor Am star are noted as well as some others for which their identity asAp or Am stars is not yet well established. The catalog gives theidentificators and the main observational data for each star, includingthe magnitude, color, spectral type, duplicity, periodicity, magneticfield, and projected rotational velocity.
| Predicting peculiar interstellar extinction from gaseous abundances
Molecular and atomic abundances are examined for 19 lines of sightthrough dense clouds, each with a peculiar selective extinction curve.The interstellar clouds appear to fall into two distinct categories:CN-rich, with relatively small amounts of neutral iron, or CN-poor, withlarge amounts of neutral iron. Lines of sight having a CN/(Fe I)abundance ratio about two or greater, are found to have a shallow 2175 Afeature relative to the underlying extinction, while the strength ofbump is 3.60 + or - 0.36 for the other dense clouds in the presentstudy. The difference is the strength of the extinction bump betweenthese two ensembles is 1.03 + or - 0.23. Several atomic abundances areexamined as potential indicators of peculiar extinction. The Mn I upperlimits in the present study support that Mn is being preferentiallydepleted. Fe I is underabundant relative to K I by 0.7 (dex) in thelarge (CN)/(Fe I) compared to the small (CN)/(Fe I) lines of sight.
| Maximum separations among cataloged binaries
The paper classifies many of the widest common-motion binaries listed inthe Aitken catalog and list 72 physical pairs with known photoelectricphotometry, 31 physical pairs without good photometry, and 27 opticalpairs. As a function of primary types, the physical systems have upperlimits to their separations that are exceeded by some of the opticalpairs. The fact that optical pairs occur with larger separations impliesthat the limits are real ones and not just catalog limitations. Thoselimits (in AU) are expressed by 2500 M1 exp 1.54 for B5-KO main-sequenceprimaries. The same limits hold for the Trapezium and hierarchicalsystems studied previously.
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| Classification d'étoiles doubles dans le système à 3 paramètres λ,D, Φb
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Observation and Astrometry data
| Constellation: | Ταύρος |
| Right ascension: | 04h23m57.77s |
| Declination: | +24°18'13.9" |
| Apparent magnitude: | 7.912 |
| Distance: | 264.55 parsecs |
| Proper motion RA: | 5.1 |
| Proper motion Dec: | -7.7 |
| B-T magnitude: | 8.257 |
| V-T magnitude: | 7.941 |
Catalogs and designations:
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