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Discoveries from a Near-infrared Proper Motion Survey Using Multi-epoch Two Micron All-Sky Survey Data
We have conducted a 4030 deg2 near-infrared proper motionsurvey using multi-epoch data from the Two Micron All-Sky Survey(2MASS). We find 2778 proper motion candidates, 647 of which are notlisted in SIMBAD. After comparison to Digitized Sky Survey images, wefind that 107 of our proper motion candidates lack counterparts at B, R,and I bands and are thus 2MASS-only detections. We present results ofspectroscopic follow-up of 188 targets that include the infrared-onlysources along with selected optical-counterpart sources with faintreduced proper motions or interesting colors. We also establish a set ofnear-infrared spectroscopic standards with which to anchor near-infraredclassifications for our objects. Among the discoveries are six youngfield brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelveM-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. Wefurther refine the definitions of these exotic classes to aid futureidentification of similar objects. We examine their kinematics and findthat both the "blue L" and "red L" dwarfs appear to be drawn from arelatively old population. This survey provides a glimpse of the kindsof research that will be possible through time-domain infrared projectssuch as the UKIDSS Large Area Survey, various VISTA surveys, and WISE,and also through z- or y-band enabled, multi-epoch surveys such asPan-STARRS and LSST.Some of the spectroscopic data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership amongthe California Institute of Technology, the University of California,and the National Aeronautics and Space Administration. The Observatorywas made possible by the generous financial support of the W. M. KeckFoundation. Other spectroscopic data were collected at the SubaruTelescope, which is operated by the National Astronomical Observatory ofJapan.
| 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.
| BVR photoelectric photometry of late-type stars and a compilation of other data in the Small Magellanic Cloud
The basic data used in a discussion of the structure and morphology ofthe SMC Martin et al., (1989) are presented. New BVR photoelectric dataacquired at ESO, 88 SMC K-M type supergiants and three foreground Mstars; for all these stars, high-accuracy Coravel radial velocities hadbeen obtained. Taking into account all available data, a list of mean Vmagnitudes is obtained for 307 stars in the direction of the SMC withknown radial velocities. Also established is a list of mean weightedradial velocities on the IAU standard system for the 307 stars (amongwhich only two are probably foreground Galactic stars).
| The structure of the Small Magellanic Cloud
The structure of the SMC is investigated using previous H-I data,accurate radial velocities of 307 young stars and 35 H-II regions, andhigh-spectral-resolution profiles of interstellar absorption lines. Itis found that 224 stars and 30 H-II regions of the main body of the SMCare associated with four H-I components, and that 54 of the objects arenot associated with H I. Two main complexes of gas, stars, and H-IIregions are found, one with a velocity of about -28 km/s and the otherwith a velocity of about +9 km/s. Most of the young stars are shown tolie within a depth smaller than 10 kpc, in agreement with recentMagellanic Cepheid data.
| Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. VI - 233 F to M type stars in and near the Small Magellanic Cloud - Comparison with 80 spectrographic radial velocities of O to K type stars in this galaxy
Abstract image available at:http://adsabs.harvard.edu/abs/1987A&AS...67..423M
| Small Magellanic Cloud, additional lists of probable members and foreground stars
The continuation of a survey in the direction of the Small MagellanicCloud has made it possible to detect fourteen new probable members. MKspectral types, V magnitudes, (B-V) and (U-B) color indices, and remarksare given for these stars and also for eleven members already publishedwithout photometric data in a previous catalog; four new Wolf-Rayetstars detected in a specific survey by Azzopardi and Breysacher (1978)are added in order to complete the list of SMC members. An additionallist of 124 foreground stars in the direction of the SMC is presented,giving UBV photometry, remarks and an estimate of spectral type for mostof them. Coordinates for 1975 and finding charts are provided.
| MK classification in the Small Magellanic cloud
This paper compares in detail the spectra of SMC supergiants with thoseof galactic supergiants. The helium and metallic lines are weaker in theformer, but not uniformly so for all metals. Also the Balmer jump issmall compared with standards, and some stars have quite large hydrogenprofiles. Other peculiar features are described.
| Etude DU Petit Nuage de Magellan par la technique DU prisme-objectif de Fehrenbach.
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Membre dels grups següents:
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Dades d'Observació i Astrometria
| Constel·lació: | Tucana |
| Ascensió Recta: | 00h29m33.84s |
| Declinació: | -72°40'56.2" |
| Magnitud Aparent: | 10.978 |
| Moviment propi RA: | 210.6 |
| Moviment propi Dec: | -84.6 |
| B-T magnitude: | 11.8 |
| V-T magnitude: | 11.046 |
Catàlegs i designacions:
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