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Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants
We present the parameters of 891 stars, mostly clump giants, includingatmospheric parameters, distances, absolute magnitudes, spatialvelocities, galactic orbits and ages. One part of this sample consistsof local giants, within 100 pc, with atmospheric parameters eitherestimated from our spectroscopic observations at high resolution andhigh signal-to-noise ratio, or retrieved from the literature. The otherpart of the sample includes 523 distant stars, spanning distances up to1 kpc in the direction of the North Galactic Pole, for which we haveestimated atmospheric parameters from high resolution but lowsignal-to-noise Echelle spectra. This new sample is kinematicallyunbiased, with well-defined boundaries in magnitude and colours. Werevisit the basic properties of the Galactic thin disk as traced byclump giants. We find the metallicity distribution to be different fromthat of dwarfs, with fewer metal-rich stars. We find evidence for avertical metallicity gradient of -0.31 dex kpc-1 and for atransition at ~4-5 Gyr in both the metallicity and velocities. Theage-metallicity relation (AMR), which exhibits a very low dispersion,increases smoothly from 10 to 4 Gyr, with a steeper increase for youngerstars. The age-velocity relation (AVR) is characterized by thesaturation of the V and W dispersions at 5 Gyr, and continuous heatingin U.
| The stellar population of the Rosat North Ecliptic Pole survey
Context: .X-ray surveys are a very efficient mean of detecting youngstars and therefore allow us to study the young stellar population inthe solar neighborhood and the local star formation history in the lastbillion of years. Aims: .We want to study the young stellarpopulation in the solar neighborhood, to constrain its spatial densityand scale height as well as the recent local star formation history. Methods: .We analyze the stellar content of the ROSAT North EclipticPole survey, and compare the observations with the predictions derivedfrom stellar galactic model. Since the ROSAT NEP survey is sensitive atintermediate fluxes is able to sample both the youngest stars and theintermediate age stars (younger than 109 years), linking theshallow and deep flux surveys already published in the literature. Results: .We confirm the existence of an excess of yellow stars inour neighborhood previously seen in shallow survey, which is likely dueto a young star population not accounted for in the model. However theexcellent agreement between observations and predictions of dM starscasts some doubt on the real nature of this active population.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)
The LSPM catalog is a comprehensive list of 61,977 stars north of theJ2000 celestial equator that have proper motions larger than 0.15"yr-1 (local-background-stars frame). The catalog has beengenerated primarily as a result of our systematic search for high propermotion stars in the Digitized Sky Surveys using our SUPERBLINK software.At brighter magnitudes, the catalog incorporates stars and data from theTycho-2 Catalogue and also, to a lesser extent, from the All-SkyCompiled Catalogue of 2.5 million stars. The LSPM catalog considerablyexpands over the old Luyten (Luyten Half-Second [LHS] and New LuytenTwo-Tenths [NLTT]) catalogs, superseding them for northern declinations.Positions are given with an accuracy of <~100 mas at the 2000.0epoch, and absolute proper motions are given with an accuracy of ~8 masyr-1. Corrections to the local-background-stars propermotions have been calculated, and absolute proper motions in theextragalactic frame are given. Whenever available, we also give opticalBT and VT magnitudes (from Tycho-2, ASCC-2.5),photographic BJ, RF, and IN magnitudes(from USNO-B1 catalog), and infrared J, H, and Ks magnitudes(from 2MASS). We also provide an estimated V magnitude and V-J color fornearly all catalog entries, useful for initial classification of thestars. The catalog is estimated to be over 99% complete at high Galacticlatitudes (|b|>15deg) and over 90% complete at lowGalactic latitudes (|b|>15deg), down to a magnitudeV=19.0, and has a limiting magnitude V=21.0. All the northern starslisted in the LHS and NLTT catalogs have been reidentified, and theirpositions, proper motions, and magnitudes reevaluated. The catalog alsolists a large number of completely new objects, which promise to expandvery significantly the census of red dwarfs, subdwarfs, and white dwarfsin the vicinity of the Sun.Based on data mining of the Digitized Sky Surveys (DSSs), developed andoperated by the Catalogs and Surveys Branch of the Space TelescopeScience Institute (STScI), Baltimore.Developed with support from the National Science Foundation (NSF), aspart of the NASA/NSF NStars program.
| Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I.
We have embarked on a project, under the aegis of the Nearby Stars(NStars)/Space Interferometry Mission Preparatory Science Program, toobtain spectra, spectral types, and, where feasible, basic physicalparameters for the 3600 dwarf and giant stars earlier than M0 within 40pc of the Sun. In this paper, we report on the results of this projectfor the first 664 stars in the northern hemisphere. These resultsinclude precise, homogeneous spectral types, basic physical parameters(including the effective temperature, surface gravity, and overallmetallicity [M/H]), and measures of the chromospheric activity of ourprogram stars. Observed and derived data presented in this paper arealso available on the project's Web site.
| 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.
| Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalog
We present refined coordinates and proper-motion data for the highproper-motion (HPM) stars in the Luyten Half-Second (LHS) catalog. Thepositional uncertainty in the original Luyten catalog is typicallygreater than 10" and is often greater than 30". We have used the digitalscans of the POSS I and POSS II plates to derive more accurate positionsand proper motions of the objects. Out of the 4470 candidates in the LHScatalog, 4323 objects were manually reidentified in the POSS I and POSSII scans. A small fraction of the stars were not found because of thelack of finder charts and digitized POSS II scans. The uncertainties inthe revised positions are typically ~2" but can be as high as ~8" in afew cases, which is a large improvement over the original data.Cross-correlation with the Tycho-2 and Hipparcos catalogs yielded 819candidates (with mR<~12). For these brighter sources, theposition and proper-motion data were replaced with the more accurateTycho-2/Hipparcos data. In total, we have revised proper-motionmeasurements and coordinates for 4040 stars and revised coordinates for4330 stars. The electronic version of the paper5 contains the updated information on all 4470stars in the LHS catalog.
| Photometric Measurements of the Fields of More than 700 Nearby Stars
In preparation for optical/IR interferometric searches for substellarcompanions of nearby stars, we undertook to characterize the fields ofall nearby stars visible from the Northern Hemisphere to determinesuitable companions for interferometric phase referencing. Because theKeck Interferometer in particular will be able to phase-reference oncompanions within the isoplanatic patch (30") to about 17th magnitude atK, we took images at V, r, and i that were deep enough to determine iffield stars were present to this magnitude around nearby stars using aspot-coated CCD. We report on 733 fields containing 10,629 measurementsin up to three filters (Gunn i, r and Johnson V) of nearby stars down toabout 13th magnitude at V.
| X-Ray Activity in the Open Cluster IC 4665
We present the results of a joint ROSAT High Resolution Imager (HRI) andoptical investigation of the open cluster IC 4665. The ROSAT datacontains detections for 28 stellar sources in the field, including 22cluster members and candidate members spanning the color range -0.18<= (B-V)0 <= 1.63 (~B3-M3). Upper limits are given for theremaining members (or candidate members) in the HRI field. Keck HIRESspectra have been obtained that yield radial and rotational velocitymeasures, respectively, for faint, low-mass candidate members locatedwithin the field of the ROSAT HRI observation. In addition, photometryof possible optical counterparts to previously uncataloged X-ray sourcesin the HRI field is presented. The trends in X-ray properties with B-Vcolor in IC 4665 are found to be quite similar to that for other, morenearby young clusters such as the Pleiades and alpha Persei. Inparticular a maximum in normalized X-ray luminosity of log (LX/Lbol) ~=-3 is observed, beginning in the color range of (B-V)0 = 0.7-0.8. Thisis similar to the corresponding color range among Pleiades members, inagreement with the earlier estimate by Prosser & Giampapa that theage of IC 4665 is similar to the age of the Pleiades. The correlation ofrotation and X-ray emission levels is consistent with that in otheryoung clusters. Among the high-mass stars in IC 4665, five B stars aredetected as X-ray sources. Of these, one is a spectroscopic binary whilethe remaining objects are apparently single stars. The level ofintrinsic X-ray emission observed in the rapidly rotating (v sin i >200 km s-1), single B stars is consistent with an origin due to shockheating of the ambient medium by radiatively driven, rotationallyenhanced winds. On the basis of these observations and the results forother clusters, we argue that observed levels of X-ray emission inhigh-mass stars of log (LX/Lbol) > -6.0 are likely due to intrinsicemission associated with the B star itself rather than emission from alate-type secondary. Finally, our results suggest that the initialangular momentum distributions and the subsequent evolution of rotation,LX, and (LX/Lbol) occur in practically identical fashions in clusterswith ages <~100 Myr.
| Quantitative spectral classification of galactic disc K-M stars from spectrophotometric measurements
New spectral observations for 47 southern galactic red supergiantsobtained with the new RUBIKON spectrophotometer (developed at theAstronomisches Institut der Ruhr-Universitat Bochum) at the Bochum 61-cmtelescope on La Silla are presented. The spectra range from 4800 to 7700A and their resolution is 10 A. The mean error of absolute fluxes is0.028 mag and that of relative fluxes 0.021 mag. The spectra will beavailable at the Strasbourg Stellar Database (CDS). Together with datataken from recently published spectral catalogues, the new observationshave been used to define spectral indices as measures of the strengthsof the following features: Fe i+TiOalpha_1, Mgb+TiOalpha_0,NaD+TiOgamma'_1, TiOgamma'_0 and TiOgamma_1 systems. The indices havebeen checked against errors introduced by reductions, interstellarreddening and different resolutions of different spectral catalogues,and have been found to be very insensitive to all these effects.Therefore, different catalogues may be combined without any loss ofaccuracy and homogeneity. The mean error of a single index has beenfound to be 0.011 mag. For stars from K4 to M7, a strong temperaturedependence is found for all indices. For the Fe i+TiO and especially theMgb+TiO features, a strong dependence on luminosity has also beenobserved. These indices therefore have been combined to form aluminosity index, while the others together form a spectral index. Thecombined indices have been calibrated in terms of MK data using thestepwise linear regression technique, and may be used for quantitativetwo- dimensional spectral classification of late K- and M-type stars.The mean error of the classification is 0.6 of spectral subtype and 0.8of luminosity class, which is much higher than would be expected fromthe uncertainty of the indices alone (which, e.g., for an M4 giantcorrespond to an uncertainty of 0.1 of spectral subtype and 0.3 ofluminosity class). This may be explained by the uncertainty of theoriginal MK classifications and the variability of some programme stars.
| Photometry of Stars with Large Proper Motion
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.2300W&db_key=AST
| The catalogue of nearby stars metallicities.
Not Available
| Classification of Population II Stars in the Vilnius Photometric System. I. Methods
The methods used for classification of Population II stars in theVilnius photometric system are described. An extensive set of standardswith known astrophysical parameters compiled from the literature sourcesis given. These standard stars are classified in the Vilnius photometricsystem using the methods described. The accuracy of classification isevaluated by a comparison of the astrophysical parameters derived fromthe Vilnius photometric system with those estimated from spectroscopicstudies as well as from photometric data in other systems. For dwarfsand subdwarfs, we find a satisfactory agreement between our reddeningsand those estimated in the uvbyscriptstyle beta system. The standarddeviation of [Fe/H] deter mined in the Vilnius system is about 0.2 dex.The absolute magnitude for dwarfs and subdwarfs is estimated with anaccuracy of scriptstyle <=0.5 mag.
| 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.
| Photometry of dwarf K and M stars
An observational program using UBVRI photometry is presented for 688stars from among the dwarf K and M stars already found spectroscopicallyby Vyssotsky (1958). Of these, 211 have not been observedphotometrically. These observations were obtained over a period ofseveral years at the Kitt Peak National Observatory using a GaAsphotomultiplier with an 0.9 m reflector. Based on night-to-nightvariations in the measures of individual stars, the internal errors maybe estimated to be roughly 0.01 mag for the colors and 0.015 for the Vmagnitudes. The photometric parallaxes reported for each star werecomputed in the manner discussed by Weis (1986).
| The donor star of the long-period dwarf nova DX Andromedae
Spectroscopic observations of the long-period dwarf nova DX Andromedaeare reported which show that it has a binary period of 0.44167 d, asecondary radial velocity amplitude of 107 km/s, and a projectedrotational velocity of 79 km/s. Photometric observations revealellipsoidal variation of 0.08 mag in Z. From all the data, it is foundthat DX And has a mass ratio of 0.96 and that the accretion diskcontributes about 15 percent of the light in the green region of thespectrum. The secondary has a spectral type of K1 V and a radius atleast 40 percent larger than the corresponding main sequence stars. Itis argued that the companion star mass is less than 0.8 solar. Thedistance to DX And is 630 pc. The secondary star's absorption spectrumdoes not exactly match that of a normal main-sequence star: enhancedabsorption is seen at some wavelengths.
| A new library of stellar optical spectra
Attention is given to a new digital optical stellar library consistingof spectra covering 3510-8930 R at 11-A resolution for 72 differentstellar types. These types extend over the spectral classes O-M andluminosity classes I-V. Most spectra are of solar metallicity stars butsome metal-rich and metal-poor spectra are included. This new library isquantitatively compared to two previously published libraries. It offersseveral advantages over them: it is photometrically well-calibratedindividually and consistently from star to star. Good temperature andluminosity coverage has been achieved. The incorporation of stars withwell-determined temperature, metallicity, and surface gravity parametersincreases the accuracy of the spectral type assigned to each compositelibrary star.
| Preliminary Version of the Third Catalogue of Nearby Stars
Not Available
| Photoelectric Photometry of 241 Stars in the Vilnius System
Not Available
| 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.
| G. P. Kuiper's spectral classifications of proper-motion stars
Spectral classifications are listed for over 3200 stars, mainly of largeproper motion, observed and classified by Kuiper during the years1937-1944 at the Yerkes and McDonald Observatories. While Kuiper himselfpublished many of his types, and while improved classifications are nowavailable for many of these stars, much of value remains. For many ofthe objects, no other spectral data exist.
| A library of stellar spectra
Spectra for 161 stars having spectral classes O-M and luminosity classesV, III, and I have been incorporated into a library available onmagnetic tape. The spectra extend from 3510 to 7427 A at a resolution ofabout 4.5 A. The typical photometric uncertainty of each resolutionelement in the spectra is on the order of 1 percent while broad-bandvariations are smaller than 3 percent. Potential uses for the libraryinclude population synthesis of galaxies and clusters, tests of stellaratmosphere models, spectral classification, and the generation of colorindices having arbitrary wavelength and bandpass.
| Results of the Herstmonceux parallax programme. III
Herstmonceux parallaxes measured with the 26-in. refractor for 28 starsare presented. Parameters examined include photometric V and Bmagnitudes to 0.01 mag or approximate visual and photographic magnitudesto 0.1 mag; the approximate effective photographic magnitude; theparallax weights of the right ascension and combined solutions; therelative parallax solutions and their standard errors; and the adoptedparallax, absolute magnitude, and the positive and negative rangecorresponding to the standard error of the relative parallax. A weakcorrelation appears to exist between the relative parallax solutions andright ascension. Though the phase is similar to that obtained by Thomas(1973), the variation is much smaller. Both the phase and the amplitudeof the relative parallax solutions are approximately the same as thoseobtained by Lippincott (1971).
| Observations of late-type dwarfs of the young and old disk population using DDO photometry
Intermediate-band DDO photometry is presented for 52 dwarf starscovering the spectral range from K2 to M2. All the stars have measuresof the emission intensities of the H and K lines of calcium in theirspectra, and it is suggested that thirty of these stars are young stars,based on their motion and calcium emission intensities. The DDOphotometry clearly defines the locus of the K and early M dwarfs, andshows a small separation between the young and old stars, which isinterpreted as a small difference in surface gravity and a possiblymarginal difference in cyanogen intensity.
| Some Cross-Reference Lists for the Catalog of Possible Nearby Stars
Not Available
| Catalogue of stars with CaII H and K emissions
Not Available
| Possible nearby stars brighter than tenth magnitude
Basic data are compiled for 447 stars brighter than 10th visualmagnitude which may be within 25 pc of the sun and are missing from boththe Gliese (1969) and the Woolley et al. (1970) catalogs of nearbystars. The list includes 245 stars with photometric parallaxes, 17 starswith trigonometric parallaxes, and nine stars with dynamical parallaxes,all of which parallaxes are at least 0.040 arcsec, as well as 176 likelycandidates. The stars are grouped into six categories according to thereliability of absolute-magnitude estimates and ranked within each groupon the basis of calculated distance. The distance estimates incorporatea kinematic correction to the photometric parallaxes which is based onthe size of a star's proper motion. A list of stars brighter than 10thmag which appear in the Gliese but not in the Woolley et al. catalog isalso provided to facilitate cross-reference with existing catalogs ofnearby stars.
| Three-dimensional motion of dwarf stars and RR Lyrae variables
A collection of 220 high-velocity dwarfs, 532 low-velocity dwarfs, and114 RR Lyrae variables is given in tables with calculations ofkinematical quantities in a three-dimensional model of galactic space. Ametal indicator, Delta-S, for RR Lyrae variables is transformed into theultraviolet excess, delta (0.6), which is utilized for a statisticalstudy of kinematics under the same metallicity classification. It isfound that the primordial Galaxy contracted by a factor of at least 20in the radial direction as compared to at least 50 in the Z direction.
| The motions of K and M dwarf stars of different ages
Parallax and proper-motion results are summarized for 145 nearby K and Mdwarfs, and space motions are calculated for most of the sample, whichis not biased toward stars with high velocity. The space motions andtheir U, V, and W components are presented, the mean motion and velocitydispersion of the stars are derived, and the velocity distributions arecompared with previous results. The stars are divided into groupsrepresenting the young-disk, old-disk, and halo populations, and thesizes of the groups are examined along with their kinematicalproperties. The weights of the space motions of the individual starscomprising each group are evaluated by means of a rigorous method basedon the premise that the error in tangential velocity must necessarily bea distance-dependent parameter whereas that in radial velocity is not.The results obtained indicate an outward motion of the young stars withrespect to the old ones and confirm that the kinematical local standardof rest is age-sensitive.
| Four-color photometry of late-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79.1424O&db_key=AST
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Dades d'Observació i Astrometria
| Constel·lació: | Cassiopeia |
| Ascensió Recta: | 00h57m04.42s |
| Declinació: | +69°02'36.4" |
| Magnitud Aparent: | 9.133 |
| Distancia: | 24.125 parsecs |
| Moviment propi RA: | 715 |
| Moviment propi Dec: | -233.7 |
| B-T magnitude: | 10.545 |
| V-T magnitude: | 9.25 |
Catàlegs i designacions:
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