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The Keck Aperture-masking Experiment: Near-Infrared Sizes of Dusty Wolf-Rayet Stars
We report the results of a high angular resolution near-infrared surveyof dusty Wolf-Rayet stars using the Keck I Telescope, including newmultiwavelength images of the pinwheel nebulae WR 98a, WR 104, and WR112. Angular sizes were measured for an additional eight dustyWolf-Rayet stars using aperture-masking interferometry, allowing us toprobe characteristic sizes down to ~20 mas (~40 AU for typical sources).With angular sizes and specific fluxes, we can directly measure thewavelength-dependent surface brightness and size relations for oursample. We discovered tight correlations of these properties within oursample that could not be explained by simple spherically symmetric dustshells or even the more realistic ``pinwheel nebula''(three-dimensional) radiative transfer model, when using Zubko's opticalconstants. While the tightly correlated surface brightness relations weuncovered offer compelling indirect evidence of a shared and distinctivedust shell geometry among our sample, long-baseline interferometersshould target the marginally resolved objects in our sample in order toconclusively establish the presence or absence of the putativeunderlying colliding-wind binaries thought to produce the dust shellsaround WC Wolf-Rayet stars.
| Photoelectric observations of lunar occultations. XI
Occultation observations of 466 events are presented. These includediameter measures of Aldebaran under very bad conditions and a gooddiameter measure of 82 Vir. The list includes 91 reappearances andobservations of 34 double or multiple stars, both new and previouslyknown. The inconsistencies of the observations of Kui 88 are discussed.Further observations are most desirable.
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Observation and Astrometry data
| Constellation: | Sagittarius |
| Right ascension: | 18h00m24.74s |
| Declination: | -19°13'51.6" |
| Apparent magnitude: | 7.921 |
| Distance: | 1587.302 parsecs |
| Proper motion RA: | 3.1 |
| Proper motion Dec: | -0.3 |
| B-T magnitude: | 10.176 |
| V-T magnitude: | 8.108 |
Catalogs and designations:
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