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A trend filtering algorithm for wide-field variability surveys
We show that various systematics related to certain instrumental effectsand data reduction anomalies in wide-field variability surveys can beefficiently corrected by a trend filtering algorithm (TFA) applied tothe photometric time-series produced by standard data pipelines.Statistical tests, performed on the data base of the HAT Networkproject, show that by the application of this filtering method thecumulative detection probability of periodic transits increases by up to0.4 for variables brighter than 11 mag, with a trend of increasingefficiency toward brighter magnitudes. We also show that the TFA can beused for the reconstruction of periodic signals by iteratively filteringout systematic distortions.
| Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
The availability of the Hipparcos Catalogue has triggered many kinematicand dynamical studies of the solar neighbourhood. Nevertheless, thosestudies generally lacked the third component of the space velocities,i.e., the radial velocities. This work presents the kinematic analysisof 5952 K and 739 M giants in the solar neighbourhood which includes forthe first time radial velocity data from a large survey performed withthe CORAVEL spectrovelocimeter. It also uses proper motions from theTycho-2 catalogue, which are expected to be more accurate than theHipparcos ones. An important by-product of this study is the observedfraction of only 5.7% of spectroscopic binaries among M giants ascompared to 13.7% for K giants. After excluding the binaries for whichno center-of-mass velocity could be estimated, 5311 K and 719 M giantsremain in the final sample. The UV-plane constructed from these datafor the stars with precise parallaxes (σπ/π≤20%) reveals a rich small-scale structure, with several clumpscorresponding to the Hercules stream, the Sirius moving group, and theHyades and Pleiades superclusters. A maximum-likelihood method, based ona Bayesian approach, has been applied to the data, in order to make fulluse of all the available stars (not only those with precise parallaxes)and to derive the kinematic properties of these subgroups. Isochrones inthe Hertzsprung-Russell diagram reveal a very wide range of ages forstars belonging to these groups. These groups are most probably relatedto the dynamical perturbation by transient spiral waves (as recentlymodelled by De Simone et al. \cite{Simone2004}) rather than to clusterremnants. A possible explanation for the presence of younggroup/clusters in the same area of the UV-plane is that they have beenput there by the spiral wave associated with their formation, while thekinematics of the older stars of our sample has also been disturbed bythe same wave. The emerging picture is thus one of dynamical streamspervading the solar neighbourhood and travelling in the Galaxy withsimilar space velocities. The term dynamical stream is more appropriatethan the traditional term supercluster since it involves stars ofdifferent ages, not born at the same place nor at the same time. Theposition of those streams in the UV-plane is responsible for the vertexdeviation of 16.2o ± 5.6o for the wholesample. Our study suggests that the vertex deviation for youngerpopulations could have the same dynamical origin. The underlyingvelocity ellipsoid, extracted by the maximum-likelihood method afterremoval of the streams, is not centered on the value commonly acceptedfor the radial antisolar motion: it is centered on < U > =-2.78±1.07 km s-1. However, the full data set(including the various streams) does yield the usual value for theradial solar motion, when properly accounting for the biases inherent tothis kind of analysis (namely, < U > = -10.25±0.15 kms-1). This discrepancy clearly raises the essential questionof how to derive the solar motion in the presence of dynamicalperturbations altering the kinematics of the solar neighbourhood: doesthere exist in the solar neighbourhood a subset of stars having no netradial motion which can be used as a reference against which to measurethe solar motion?Based on observations performed at the Swiss 1m-telescope at OHP,France, and on data from the ESA Hipparcos astrometry satellite.Full Table \ref{taba1} 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/430/165}
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| A catalogue of [Fe/H] determinations: 1996 edition
A fifth Edition of the Catalogue of [Fe/H] determinations is presentedherewith. It contains 5946 determinations for 3247 stars, including 751stars in 84 associations, clusters or galaxies. The literature iscomplete up to December 1995. The 700 bibliographical referencescorrespond to [Fe/H] determinations obtained from high resolutionspectroscopic observations and detailed analyses, most of them carriedout with the help of model-atmospheres. The Catalogue is made up ofthree formatted files: File 1: field stars, File 2: stars in galacticassociations and clusters, and stars in SMC, LMC, M33, File 3: numberedlist of bibliographical references The three files are only available inelectronic form at the Centre de Donnees Stellaires in Strasbourg, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
| A critical appraisal of published values of (Fe/H) for K II-IV stars
'Primary' (Fe/H) averages are presented for 373 evolved K stars ofluminosity classes II-IV and (Fe/H) values beween -0.9 and +0.21 dex.The data define a 'consensus' zero point with a precision of + or -0.018 dex and have rms errors per datum which are typically 0.08-0.16dex. The primary data base makes recalibration possible for the large(Fe/H) catalogs of Hansen and Kjaergaard (1971) and Brown et al. (1989).A set of (Fe/H) standard stars and a new DDO calibration are given whichhave rms of 0.07 dex or less for the standard star data. For normal Kgiants, CN-based values of (Fe/H) turn out to be more precise than manyhigh-dispersion results. Some zero-point errors in the latter are alsofound and new examples of continuum-placement problems appear. Thushigh-dispersion results are not invariably superior to photometricmetallicities. A review of high-dispersion and related work onsupermetallicity in K III-IV star is also given.
| Washington photometry of open cluster giants - The metal-rich clusters
Abundances of more than one hundred giants in a large sample ofmetal-rich open clusters in the Galaxy are investigated with Washingtonphotometry. Most of these clusters have no high-dispersion spectroscopicabundance determinations. A revision of the empirical abundancecalibrations for Population I giants, based on a much improved data setover previous calibrations, is first presented. The M-T(1) (Feabundance) calibration changes slightly for stars with Fe/H of about-0.5. The C-M (Fe + CN abundance) calibration is substantially alteredfor abundances above solar. The net effect brings the two abundanceindices into close agreement and eliminates the apparent CN enhancementspreviously determined for several open clusters. An enhanced sensitivityto Fe abundance is found for both the M - T(1) and especially the C - Mindex over that determined in previous investigations. Indeed, Delta(C -M) has an Fe abundance sensitivity that exceeds any other photometricabundance index. In view of the relative rarity of CN strengthvariations in Pop I giants, this index is most useful as a metallicityindicator for these stars. Abundances with an uncertainty of about 0.1dex are derived for a total of 18 open clusters observed with theWashington system. The abundances are generally in good agreement withprior abundance analyses. No strong evidence is found for CN variationsor anomalies in any of the clusters. A comparison with Population Ifield giants shows that the open cluster giants have normal CNabundances for their FE abundances.
| A catalogue of Fe/H determinations, 1984 edition
The present version of the Cayrel de Strobel et al. (1981) catalog ofFe/H abundance ratio determinations contains 1921 values for 1035 stars,which represents an augmentation over the previous publication of 48 and47 percent, respectively. In addition, the literature search conductedis complete up to December, 1983. Stellar metal abundance, effectivetemperature, spectroscopic gravity, spectral type, and photometricindices are covered.
| Study of the intermediate-age galactic cluster NGC 2281. I. UBV photoelectric observations, binary frequency, and the luminosity function of bright members.
Abstract image available at:http://adsabs.harvard.edu/abs/1978PASJ...30..123Y
| Determination of atmospheric parameters for G and K giants by means of photoelectric indices.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....15..123H&db_key=AST
| Photoelectric Photometry of 1160 Late-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....2....1D&db_key=AST
| Radial Velocities of Yellow Giants in Four Galactic Clusters
Not Available
| Photometric and Objective Prism Observations in Three Galactic Clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1961ApJ...134..602P&db_key=AST
| Relative proper motions of stars in the region of the open cluster NGC 2281.
Abstract image available at:http://adsabs.harvard.edu/abs/1959AJ.....64..170V
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Dades d'Observació i Astrometria
| Constel·lació: | Auriga |
| Ascensió Recta: | 06h48m21.72s |
| Declinació: | +41°18'08.4" |
| Magnitud Aparent: | 7.239 |
| Distancia: | 5555.556 parsecs |
| Moviment propi RA: | -2.6 |
| Moviment propi Dec: | -7.5 |
| B-T magnitude: | 9.016 |
| V-T magnitude: | 7.386 |
Catàlegs i designacions:
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