תוכן
תמונות
הוסף תמונה שלך
DSS Images Other Images
מאמרים קשורים
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.
| Astrometric positions of stars with high proper motions in the Southern Hemisphere
Several stars with large proper motions, cited by W.J. Luyten, wereincluded in the preliminary programme for the HIPPARCOS mission. Whenperforming preparatory measurements of plates, difficulties wereencountered in identifying certain of these stars when relying only onpublished coordinates. We have taken advantage of this work whichrelates to the southern sky in order to determine the astrometricposition of the greatest possible number of these objects, even forthose which were not included in the programme. Catalogue is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Luminosities, abundances, and motions of stars brighter than visual magnitude 15.1 and annual proper motions larger than one-half arcsecond
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987AJ.....93..393E&db_key=AST
| Catalog of proper-motion stars. III - Stars brighter than visual magnitude 15.1, south of declination +30 deg, and with annual proper motion between 0.5 and 0.7 arcsec
A catalog of (VRI) photometry for the some one thousand stars withannual proper motion between 0.5 and 0.7 arcsec, brighter than visualmagnitude 15.1, and south of declination +30 deg is presented. Theavailable proper-motion and radial-velocity data are also summarized.
| The stellar component of the galaxy as seen by the AFGL infrared sky survey
The noise-limited magnitudes for the Air Force Geophysical Laboratory(AFGL) Infrared Sky Survey have been estimated by direct comparison withground-based observations. Using these limiting magnitudes, 'pruned'versions of the AFGL catalog have been generated. Infrared observationsof all the stellar objects seen at 11, 20, or 27 microns and astatistical sample of the stars seen only at 4 microns are reported.Analysis of the observations leads to estimates of the absolute 4 and 10microns magnitudes and space densities for the two clases of objects.The expected results from the Infrared Astronomical Satellite arereexamined.
| Measurement of unambiguous rotation measures of extragalactic sources
The results are reported of polarization measurements conductedspecifically to check for the existence of very high Faraday rotationmeasures, which might otherwise have been undetected. Polarizationmeasurements are presented for 24 extragalactic radio sources at 4contiguous bands around 9 cm, from observations at the NRAO 300 ft.telescope. It is shown how these measurements can be used to deriverotation measures (and limits) which are free from n pi phaseambiguities around 9 cm. It is found that the data can not be madeconsistent with arbitrarily large rotation measures. Revised rotationmeasures and initial position angles are presented for the observedsources.
| Visual multiples. VII - MK classifications
Classifications are given for 865 components of visual multiples; theyshow no systematic differences from the MK system, and the random errorsare one subclass in type and two-thirds of a luminosity class. It isfound that at least 1% of the F-type IV and V stars are weak-lined, 32%of the A4-F1 IV and V stars are Am, and 5% of the A0-A3 IV and V starsare early-type Am. Attention is called to the large fraction (55%) ofthe A3-A9 III-V stars that are of luminosity classes III or IV, unlikethe percentage (16%) at neighboring types.
|
הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
|
תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | אוקטנט |
| התרוממות ימנית: | 03h10m40.44s |
| סירוב: | -84°32'35.4" |
| גודל גלוי: | 10.269 |
| תנועה נכונה: | 591.6 |
| תנועה נכונה: | 208.6 |
| B-T magnitude: | 11.247 |
| V-T magnitude: | 10.35 |
קטלוגים וכינוים:
|
