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Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are 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/418/989
| Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.
| A Survey of Proper-Motion Stars. XVI. Orbital Solutions for 171 Single-lined Spectroscopic Binaries
We report 25,563 radial velocity measurements for 1359 single-linedstars in the Carney-Latham sample of 1464 stars selected for high propermotion. For 171 of these, we present spectroscopic orbital solutions. Wefind no obvious difference between the binary characteristics in thehalo and the disk populations. The observed frequency is the same, andthe period distributions are consistent with the hypothesis that the twosets of binaries were drawn from the same parent population. Thissuggests that metallicity in general, and radiative opacities inparticular, have little influence over the fragmentation process thatleads to short-period binaries. All the binaries with periods shorterthan 10 days have nearly circular orbits, while the binaries withperiods longer than 20 days exhibit a wide range of eccentricities and amedian value of 0.37. For the metal-poor high-velocity halo binaries inour sample, the transition from circular to eccentric orbits appears tooccur at about 20 days, supporting the conclusion that tidalcircularization on the main sequence is important for the oldestbinaries in the Galaxy. Some of the results presented here usedobservations made with the Multiple Mirror Telescope, a joint facilityof the Smithsonian Institution and the University of Arizona.
| Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
The Hipparcos satellite made measurements of over 9734 known doublestars, 3406 new double stars, and 11,687 unresolved but possible doublestars. The high angular resolution afforded by speckle interferometrymakes it an efficient means to confirm these systems from the ground,which were first discovered from space. Because of its coverage of adifferent region of angular separation-magnitude difference(ρ-Δm) space, speckle interferometry also holds promise toascertain the duplicity of the unresolved Hipparcos ``problem'' stars.Presented are observations of 116 new Hipparcos double stars and 469Hipparcos ``problem stars,'' as well as 238 measures of other doublestars and 246 other high-quality nondetections. Included in these areobservations of double stars listed in the Tycho-2 Catalogue andpossible grid stars for the Space Interferometry Mission.
| Chromospheric CaII H and K emission among subdwarfs
Echelle spectra have been obtained of the CaII H and K lines for asample of metal-poor subdwarf stars as well as for a number of nearbyPopulation I dwarfs selected from among those included in the MountWilson HK survey. The main conclusion of this paper is that CaII H- andK-line emission does occur among subdwarfs. It is particularly notableamong those subdwarfs with colours of B-V>=0.75 all such starsobserved exhibit chromospheric emission, although emission is observedamong some subdwarfs bluer than this colour. The CaII K emission profilein most subdwarfs exhibits an asymmetry of V/R>1, similar to thatseen in the integrated light of the solar disc. Two quantitativeindicators of the contrast between the peaks in the emission profile andthe neighbouring photospheric line profile are introduced. Measurementsof these indicators show that the level of CaII emission among thesubdwarfs is similar to that among low-activity Population I dwarfs.
| ROSAT all-sky survey observations of PopII field binaries: X-ray activity of old, metal-poor stellar coronae.
This study represents the first X-ray observations of an extended sampleof Pop II field binaries, aimed at investigating the properties of old,metal-poor stellar coronae. Analysing X-ray observations from the ROSATall-sky survey, we detected only 13 (out of 86) Pop II systems (15%detection rate). The X-ray luminosity function, taking into account bothdetections and upper limits, has its median at logL_x_<=28.1erg/s,indicating a low average X-ray luminosity, with a high-luminosity tailat logL_x_~29-31erg/s. The only extreme metal-poor system detected is HD89499. Thus, the detection rate of extreme Pop II systems is lower thanof intermediate Pop II, possibly indicating extreme Pop II to betypically less luminous. The X-ray luminosity is not very wellcorrelated with orbital period; long-period Pop II binaries may havehigh X-ray luminosities and, surprisingly, short-period systems are notper se strong X-ray emitters. For a subsample of emission-line Pop IIbinaries, i.e. the halo component analogs to the RS CVn binaries, themedian X-ray luminosity is at least one order of magnitude lower thanfor the RS CVns. The lower activity levels of the Pop II systems may becaused in part by the presence of fewer evolved stars in the sample andlower metallicity. The extremely old age of Pop II binaries may alsogive rise to the unexpectedly low X-ray luminosities of some systems(e.g., CD-481741, BD+53080).
| 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 survey of proper motion stars. 12: an expanded sample
We report new photometry and radial velocities for almost 500 stars fromthe Lowell Proper Motion Catalog. We combine these results with ourprior sample and rederive stellar temperatures based on the photometry,reddening, metallicities (using chi squared matching of our 22,500 lowSignal to Noise (S/N) high resolution echelle spectra with a grid ofsynthetic spectra), distances, space motions, and Galactic orbitalparameters for 1269 (kinematics) and 1261 (metallicity) of the 1464stars in the complete survey. The frequency of spectroscopic binariesfor the metal-poor ((m/H) less than or equal to -1.2) stars with periodsshorter than 3000 days is at least 15%. The spectroscopic binaryfrequency for metal-rich stars ((m/H) greater than -0.5) appears to belower, about 9%, but this may be a selection effect. We also discussspecial classes of stars, including treatment of the double-linedspectroscopic binaries, and identification of subgiants. Four possiblenew members of the class of field blue stragglers are noted. We pointout the detection of three possible new white dwarfs, six broad-lined(binary) systems, and discuss briefly the three already knownnitrogen-rich halo dwarfs. The primary result of this paper will beavailable on CD-ROM, in the form of a much larger table.
| A survey of proper-motion stars. VI - Orbits for 40 spectroscopic binaries
Orbital solutions are reported for 40 binaries in the Carney and Latham(1987) survey of proper-motion stars. The earlier orbital solutions forHD 85091, BD + 13 3683 deg, and HD 195987 are confirmed, and that for BD-3 2525 deg is revised. The number of orbital solutions for metal-poorbinaries has been increased from five to 19, six of which have doublelines. For periods longer than 20 days, the distribution of orbitaleccentricity for the metal-poor binaries is similar to that for themetal-rich binaries. For the metal-poor binaries, it is found that allthe short-period orbits are circular, with a transition to eccentricorbits at a period somewhere between 13 and 18 days. Presumably, theclose binaries with short periods were formed with eccentric orbitswhich were subsequently circularized by tidal mechanisms.
| A survey of proper-motion stars. III - Reddenings, distances, and metallicities
Further data on the Lowell proper-motion stars surveyed by Carney andLatham (1987) are presented. Both new and published photometry aresummarized for 286 of these stars. Included are R-I data for 64 stars,uvby (or by) data for 221 stars (of which are included new results for152 stars), and JHK (or K) data for 238 stars (of which are included newresults for 180 stars). The procedures used to estimate the reddeningand photometric parallax of each star are discussed. The metallicitiesfor 818 stars, based on 5795 spectra, determined using a new method,described in an earlier paper, which compares synthetic spectra to thelow-signal-to-noise spectra obtained for radial velocities are alsopresented. The reddening, distance, and metallicity are interdependentand have been determined in a self-consistent manner.
| A survey of proper-motion stars. I - UBV photometry and radial velocities
The background, motivation, and goals of a photometric and spectroscopicsurvey of over 900 stars selected from the Lowell Proper Motion Surveywithout any metallicity bias are discussed, and 1225 new UBV measures of867 stars with V = 7-16 mag, and a new mean radial velocities for 914stars based on 5815 high-resolution spectra are presented. Theradial-velocity data indicate the binary fraction of th high-velocitystars probably exceeds 25 percent.
| Hyades and Sirius supercluster members brighter than magnitude(V) 7.1. I - The first six hours of right ascension
This is the first of four papers listing the probable members of theHyades and Sirius superclusters among stars brighter than V = 7.1 mag.The star sample is contained in the Bright Star Catalogue and itsSupplement, augmented with a further supplement of 550 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 550 starsdiscussed here, as well as for all supercluster members.
| High-tangential-velocity stars
Two lists of high tangential velocity (greater than 100 km/s) starscontained in the Lowell Northern Hemisphere proper motion surveycatalogue have been compiled, the stellar distances being inferred fromeither trigonometric or spectroscopic parallaxes. The information givenincludes equatorial coordinates, corrected photographic magnitudes,proper motions, trigonometric or spectroscopic parallaxes, and spectraltypes.
| Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
| Yerkes actinometry. Zone +73deg to +90deg.
Not Available
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| קבוצת-כוכבים: | קאסיופיאה |
| התרוממות ימנית: | 03h24m04.48s |
| סירוב: | +74°10'15.6" |
| גודל גלוי: | 6.922 |
| מרחק: | 52.604 פארסק |
| תנועה נכונה: | 182.2 |
| תנועה נכונה: | -152 |
| B-T magnitude: | 7.451 |
| V-T magnitude: | 6.966 |
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