Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES): A Catalog of Very Wide, Low-mass Pairs
We present the Sloan Low-mass Wide Pairs of Kinematically EquivalentStars (SLoWPoKES), a catalog of 1342 very-wide (projected separationgsim500 AU), low-mass (at least one mid-K to mid-M dwarf component)common proper motion pairs identified from astrometry, photometry, andproper motions in the Sloan Digital Sky Survey. A Monte Carlo-basedGalactic model is constructed to assess the probability of chancealignment for each pair; only pairs with a probability of chancealignment <=0.05 are included in the catalog. The overall fidelity ofthe catalog is expected to be 98.35%. The selection algorithm ispurposely exclusive to ensure that the resulting catalog is efficientfor follow-up studies of low-mass pairs. The SLoWPoKES catalog is thelargest sample of wide, low-mass pairs to date and is intended as anongoing community resource for detailed study of bona fide systems.Here, we summarize the general characteristics of the SLoWPoKES sampleand present preliminary results describing the properties of wide,low-mass pairs. While the majority of the identified pairs are diskdwarfs, there are 70 halo subdwarf (SD) pairs and 21 white dwarf-diskdwarf pairs, as well as four triples. Most SLoWPoKES pairs violate thepreviously defined empirical limits for maximum angular separation orbinding energies. However, they are well within the theoretical limitsand should prove very useful in putting firm constraints on the maximumsize of binary systems and on different formation scenarios. We find alower limit to the wide binary frequency (WBF) for the mid-K to mid-Mspectral types that constitute our sample to be 1.1%. This frequencydecreases as a function of Galactic height, indicating a time evolutionof the WBF. In addition, the semi-major axes of the SLoWPoKES systemsexhibit a distinctly bimodal distribution, with a break at separationsaround 0.1 pc that is also manifested in the system binding energy.Compared with theoretical predictions for the disruption of binarysystems with time, we conclude that the SLoWPoKES sample comprises twopopulations of wide binaries: an "old" population of tightly boundsystems, and a "young" population of weakly bound systems that will notsurvive more than a few Gyr. The SLoWPoKES catalog and future ancillarydata are publicly available on the Internet for utilization by theastronomy community.
| New Distant Companions to Known Nearby Stars. II. Faint Companions of Hipparcos Stars and the Frequency of Wide Binary Systems
We perform a search for faint, common proper motion companions ofHipparcos stars using the recently published Lépine-Shara ProperMotion-North catalog of stars with proper motionμ>0.15'' yr-1. Our survey uncovers a totalof 521 systems with angular separations3''<Δθ<1500'', with 15 triplesand 1 quadruple. Our new list of wide systems with Hipparcos primariesincludes 130 systems identified here for the first time, including 44 inwhich the secondary star has V>15.0. Our census is statisticallycomplete for secondaries with angular separations20''<Δθ<300'' and apparentmagnitudes V<19.0. Overall, we find that at least 9.5% of nearby(d<100 pc) Hipparcos stars have distant stellar companions withprojected orbital separations s>1000 AU. We observe that thedistribution in orbital separations is consistent with Öpik's law,f(s)ds~s-1ds, only up to a separation s~4000 AU, beyond whichit follows a more steeply decreasing power law f(s)ds~s-ldswith l=1.6+/-0.1. We also find that the luminosity function of thesecondaries is significantly different from that of the single stars'field population, showing a relative deficiency in low-luminosity(8
| 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.
|
Enviar un nou article
Enllaços Relacionats
- - No s'ha trobat enllaços -
Enviar un nou enllaç
Membre dels grups següents:
|
Dades d'Observació i Astrometria
| Constel·lació: | Bootes |
| Ascensió Recta: | 15h02m44.80s |
| Declinació: | +18°10'19.2" |
| Magnitud Aparent: | 11.229 |
| Moviment propi RA: | 163 |
| Moviment propi Dec: | -214.5 |
| B-T magnitude: | 12.633 |
| V-T magnitude: | 11.345 |
Catàlegs i designacions:
|
