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uvby-Hβ CCD photometry of NGC 1817 and NGC 1807
We have investigated the area of two NGC entries, NGC 1817 and NGC 1807,with deep CCD photometry in the uvby-Hβintermediate-band system. The photometric analysis of a selected sampleof stars of the open cluster NGC 1817 yields a reddening value of E(b-y)= 0.19±0.05, a distance modulus of V0-MV =10.9±0.6, a metallicity of [Fe/H] = -0.34±0.26 and an ageof log t = 9.05±0.05. Our measurements allow us to confirm thatNGC 1807 is not a physical cluster.Figure \ref{map} and Tables \ref{log} and \ref{chips} are only availablein electronic form at http://www.edpsciences.orgTables 4 and 5 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/426/827
| New membership determination and proper motions of NGC 1817. Parametric and non-parametric approach
We have calculated proper motions and re-evaluated the membershipprobabilities of 810 stars in the area of two NGC objects, NGC 1817 andNGC 1807. We have obtained absolute proper motions from 25 plates in thereference system of the Tycho-2 Catalogue. The plates have a maximumepoch difference of 81 years; and they were taken with the doubleastrograph at Zo-Sèstation of Shanghai Observatory, which has anaperture of 40 cm and a plate scale of 30 arcsec mm-1. Theaverage proper motion precision is 1.55 mas yr-1. Theseproper motions are used to determine the membership probabilities ofstars in the region, based on there being only one very extendedphysical cluster: NGC 1817. With that aim, we have applied and comparedparametric and non-parametric approaches to cluster/field segregation.We have obtained a list of 169 probable member stars.Table 5 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/426/819Tables 1, 2 and 4 and Fig. 1 are only available in electronic form athttp://www.edpsciences.org
| 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.
| Determination of proper motions and membership of the open clusters NGC 1817 and NGC 1807
Relative proper motions, their corresponding observed errors andmembership probabilities of 722 stars in the old open cluster NGC 1817region are determined from PDS measurements of 12 plate pairs. Theplates have the maximum epoch difference of 81 years and were taken withthe double astrograph at Zǒ-Sè station of ShanghaiObservatory, which has an aperture of 40 cm, a focal length of 6.9 m anda plate scale of 30''/mm. The average proper motion accuracy is 1.6mas/yr. These proper motions are used to determine the membershipprobabilities of stars in the region. The existence of two clusters inthe region (NGC 1817, NGC 1807) is discussed. The number of stars withmembership probability higher than 0.7 is 416 for NGC 1817 and 14 forNGC 1807. Table 5 is only available in electronic form from CDS viaanonymous ftp 130.79.128.5, and by e-mail request tolbalague@pchpc3.am.ub.es
| Dwarf K and M stars of high proper motion found in a hemispheric survey
A recently completed visual/red spectral region objective-prism surveyof more than half the sky found some 2200 dwarf K and M stars ofnegligible proper motion (Stephenson, 1986). The present paper adds the1800-odd spectroscopically identified dwarfs that did prove to havesignificant proper motions. About half of these had previous spectralclassifications of some sort, especially by Vyssotsky (1952, 1956). Forthe great majority, the present coordinates are more accurate thanprevious data. The paper includes about 50 stars with unpublishedparallaxes, likely to have parallaxes of 0.05 arcsec or more. Combiningthe present data with the first paper suggests that the number oflow-proper-motion stars in that paper was not unreasonable.
| New subdwarfs. IV - UBV photometry of 1690 high-proper-motion stars
A photometric list of 1690 stars of known high proper motion is used tosearch for potential high-velocity stars of various metallicity valuesin order to find candidates for trigonometric programs on subdwarfs andto enlarge the sample with which to study the relation between stellarkinematics and metal abundance. A list of 113 stars with tangentialspace velocities of 300 km/s or greater is obtained, the highesttangential velocity relative to the sun being 630 km/s. By using thevariation of the tangential velocity with longitude and adopting thegalactic rotation at the solar circle to be 220 km/s, the rotation ofthe subdwarf system is estimated at 0 + or - 50 km/s from the transversevelocity alone, in agreement with determinations based on other methods.
| 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.
| Spectral types for proper motion stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..239B&db_key=AST
| Lowell proper motions III : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory
Not Available
| New proper-motion stars, (third list)
Not Available
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Посматрања и Астрометриски подаци
| Сазвежђа: | Бик |
| Ректацензија: | 05h12m47.96s |
| Deклинација: | +16°18'25.4" |
| Apparent магнитуда: | 10.642 |
| Даљина: | 42.827 parsecs |
| Proper motion RA: | 33.3 |
| Proper motion Dec: | -263.5 |
| B-T magnitude: | 12.223 |
| V-T magnitude: | 10.773 |
Каталог и designations:
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