Contenidos
Imágenes
Subir su imagen
DSS Images Other Images
Artículos relacionados
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.
| 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.
| The Metamorphosis of SN 1998bw
We present and discuss the photometric and spectroscopic evolution ofthe peculiar SN 1998bw, associated with GRB 980425, through an analysisof optical and near-IR data collected at ESO-La Silla. The spectroscopicdata, spanning the period from day -9 to day +376 (relative to Bmaximum), have shown that this supernova (SN) was unprecedented,although somewhat similar to SN 1997ef. Maximum expansion velocities ashigh as 3×104 km s-1 to some extent mask itsresemblance to other Type Ic SNe. At intermediate phases, betweenphotospheric and fully nebular, the expansion velocities(~104 km s-1) remained exceptionally high comparedto those of other recorded core-collapse SNe at a similar phase. Themild linear polarization detected at early epochs suggests the presenceof asymmetry in the emitting material. The degree of asymmetry, however,cannot be decoded from these measurements alone. The He I 1.083 and2.058 μm lines are identified, and He is suggested to lie in an outerregion of the envelope. The temporal behavior of the fluxes and profilesof emission lines of Mg I] λ4571, [O I] λλ6300,6364, and a feature ascribed to Fe are traced to stimulate futuremodeling work. The uniqueness of SN 1998bw became less obvious once itentered the fully nebular phase (after 1 yr), when it was very similarto other Type Ib/c-IIb objects, such as the Type Ib SN 1996N and theType IIb SN 1993J, even though SN 1998bw was 1.4 mag brighter than SN1993J and 3 mag brighter than SN 1996N at a comparable phase. Thelate-phase optical photometry, which extends up to 403 days after Bmaximum, shows that the SN luminosity declined exponentially butsubstantially faster than the decay rate of 56Co. Theultraviolet-optical-infrared bolometric light curve, constructed usingall available optical data and the early JHK photometry presented inthis work, shows a slight flattening starting on about day +300. Sinceno clear evidence of ejecta-wind interaction was found in the late-timespectroscopy (see also the work of Sollerman and coworkers), this may bedue to the contribution of the positrons since most γ-rays escapethermalization at this phase. A contribution from the superposed H IIregion cannot, however, be excluded. Based on observations collected atESO-La Silla.
| 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.
| Spectral classification of high-proper-motion stars
Spectral types have been found for about 900 stars of high proper motioncontained in the Lowell Observatory Northern Hemisphere proper-motionstar survey using all blue-region objective prism plates. The spectralclassification criteria are given. About eighty stars of largetangential velocity have been classified using slit spectrograms takenwith a 36-in. reflector. A new calibration of Luyten's absolutemagnitude vs reduced proper motion relation is made, and its dependenceon spectral type is investigated.
| Lowell proper motions II : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory
Not Available
|
Enviar un nuevo artículo
Enlaces relacionados
- - No se han encontrado enlaces -
En viar un nuevo enlace
Miembro de los siguientes grupos:
|
Datos observacionales y astrométricos
| Constelación: | Pegaso |
| Ascensión Recta: | 22h14m26.75s |
| Declinación: | +02°42'24.2" |
| Magnitud Aparente: | 10.356 |
| Distancia: | 30.931 parsecs |
| Movimiento Propio en Ascensión Recta: | 215.6 |
| Movimiento Propio en Declinación: | 23.7 |
| B-T magnitude: | 12.104 |
| V-T magnitude: | 10.501 |
Catálogos y designaciones:
|
