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The Disk and Environment of the Herbig Be Star HD 100546
Coronagraphic imaging of the nearest Herbig Be star with the SpaceTelescope Imaging Spectrograph (STIS) on board the Hubble SpaceTelescope, Ks (2.15 μm) imaging with ADONIS at the 3.6 m telescope atLa Silla, and mid-infrared imaging with OSCIR using the 4 m BlancoTelescope at Cerro Tololo Inter-American Observatory confirm thedetection of the disk reported by Pantin et al. and map the disk out to5" (~515 AU) in the optical and at Ks. While the source is unresolved at10 and 18 μm, it can be traced to 1.5" at 11.7 μm. We confirm thechange in the radial dependence of the disk surface brightness near 2.7"seen at 1.6 μm by Augereau et al. at Ks. No such break in the powerlaw is seen in the optical. The STIS data reveal spiral dark lanestructure, making HD 100546 the third near-zero-age main-sequence HerbigAe/Be star with structure more than 100 AU from the star. We alsooptically detect a low surface brightness envelope extending 10" (1000AU) from the star, in addition to nebulosity, which is probablyassociated with DC 292.6-7.9. The survival of the envelope throughessentially the entire pre-main-sequence lifetime of the star, coupledwith the absence of physical companions within 1500 AU of the star,suggests that envelope lifetimes owe more to the star-formingenvironment than to mass-loss activity from the Herbig Ae/Be star. Basedon observations made with the NASA/ESA Hubble Space Telescope, obtainedat the Space Telescope Science Institute, which is operated by theAssociation of Universities for Research in Astronomy, Inc., under NASAcontract NAS 5-26555. This study is part of the STIS IDT protoplanetarydisk Key Project. This work is also based on observations collected atthe European Southern Observatory, La Silla, Chile, Proposal ID63.I-0196. This work is also based on observations made at the CerroTololo Inter-American Observatory. CTIO is operated by AURA, Inc., undercooperative agreement with the National Science Foundation.
| Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| Hyades and Sirius supercluster members brighter than magnitude (V) 7.1. II - Right ascension six to twelve hours
The present star sample is contained in the Bright Star Catalogue andits Supplement, augmented with a further supplement of 788 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 788 starsdiscussed here, as well as all supercluster members.
| A Catalogue of Be-Stars
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| Observations of southern emission-line stars
A catalog of 1929 stars showing H-alpha emission on photographic platesis presented which covers the entire southern sky south of declination-25 deg to a red limiting magnitude of about 11.0. The catalog providesprevious designations of known emission-line stars equatorial (1900) andgalactic coordinates, visual and photographic magnitudes, H-alphaemission parameters, spectral types, and notes on unusual spectralfeatures. The objects listed include 16 M stars, 25 S stars, 37 carbonstars, 20 symbiotic stars, 40 confirmed or suspected T Tauri stars, 16novae, 14 planetary nebulae, 11 P Cygni stars, 9 Bep stars, 87 confirmedor suspected Wolf-Rayet stars, and 26 'peculiar' stars. Two new Tassociations are discovered, one in Lupus and one in Chamaeleon. Objectswith variations in continuum or H-alpha intensity are noted, and thedistribution by spectral type is analyzed. It is found that the skydistribution of these emission-line stars shows significantconcentrations in the region of the small Sagittarius cloud and in theCarina region.
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