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Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118
WR 118 is a highly evolved Wolf-Rayet star of theWC10 subtype surrounded by a permanent dust shell absorbing andre-emitting in the infrared a considerable fraction of the stellarluminosity. We present the first diffraction-limited 2.13 mu m speckleinterferometric observations of WR 118 with 73 masresolution. The speckle interferograms were obtained with the 6 mtelescope at the Special Astrophysical Observatory. The two-dimensionalvisibility function of the object does not show any significantdeviation from circular symmetry. The visibility curve declines towardsthe diffraction cut-off frequency to ~ 0.66 and can be approximated by alinear function. Radiative transfer calculations have been carried outto model the spectral energy distribution, given in the range of 0.5-25mu m, and our 2.13 mu m visibility function, assuming spherical symmetryof the dust shell. Both can be fitted with a model containingdouble-sized grains (``small'' and ``large'') with the radii of a = 0.05mu m and 0.38 mu m, and a mass fraction of the large grains greater than65%. Alternatively, a good match can be obtained with the grain sizedistribution function n(a) ~ a-3, with a ranging between0.005 mu m and 0.6 mu m. At the inner boundary of the modelled dustshell (angular diameter Thetain = (17 +/- 1) mas), thetemperature of the smallest grains and the dust shell density are 1750 K+/- 100 K and (1 +/- 0.2) x 10-19 g/cm3,respectively. The dust formation rate is found to be (1.3 +/- 0.5) x10-7 Msun/yr, assuming Vwind = 1200 kms-1.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
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Osservazione e dati astrometrici
| Costellazione: | Serpente |
| Ascensione retta: | 17h53m03.60s |
| Declinazione: | -10°53'59.0" |
| Magnitudine apparente: | 6.18 |
| Distanza: | 83.752 parsec |
| Moto proprio RA: | 44.5 |
| Moto proprio Dec: | -29 |
| B-T magnitude: | 7.618 |
| V-T magnitude: | 6.301 |
Cataloghi e designazioni:
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