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.
| EC 19314 - 5915 - A bright, eclipsing cataclysmic variable from the Edinburgh-Cape Blue Object Survey
A deeply eclipsing cataclysmic variable, with an orbital period of 4.75hr, has been discovered in the southern Edinburgh-Cape Blue ObjectSurvey. The star, EC 19314 - 5915, lies close to the positionalconstraints of a previously unidentified HEAO-1 hard X-ray source,1H1930 - 5989. Its optical spectrum is unusual in that it shows, apartfrom the emission lines characteristic of a novalike, or dwarf novacataclysmic variable (Balmer, He I and He II), metallic absorption linestypical of a late-G star. The individual time-resolved spectra, with thetertiary absorption lines removed, show absorption reversals in theBalmer emission lines, increasing in strength for the higher series. TheBalmer emission radial velocities are therefore severely distorted incomparison to the He II 4686-A emission and He I 4471-A absorptionradial velocity curves. An independent distance estimate of about 600 pcis derived for EC19314 - 5915, from the spectroscopic parallax of thethird star.
| Estimation of stellar intrinsic colours, distances and colour excesses based on the Stromgren and H-beta photometry of 804 B, A, and F stars in 10 Selected Areas
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989A&AS...78..105F&db_key=AST
| Four-colour UVBY and H-beta photometry of all A3 to F5 stars brighter than m(pg) = about 11.0 mag in 6 Selected Areas close to the Galactic plane
Photometric observations of 540 A3-F5 stars in Selected Areas 171, 173,175, 177, 192, and 195 of the Potsdam survey (Becker and Brueck,1929-1938) are reported. Data obtained in the Stromgren uvby-beta systemusing a 6-channel spectrograph-photometer on the 50-cm Danish telescopeat ESO on 98 nights during 1986-1987 are presented in extensive tablesand graphs and briefly characterized. Comparisons with previousobservations of some program stars reveal no systematic differences inmagnitude or spectral indices.
|
הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
|
תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | מחוגה |
| התרוממות ימנית: | 15h01m35.62s |
| סירוב: | -59°38'40.3" |
| גודל גלוי: | 9.073 |
| תנועה נכונה: | -118.1 |
| תנועה נכונה: | -239 |
| B-T magnitude: | 10.083 |
| V-T magnitude: | 9.157 |
קטלוגים וכינוים:
|
