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Far-Ultraviolet and Optical Observations of BW Vulpeculae
We have compared the behavior of 39 Far-Ultraviolet SpectroscopicExplorer spectra through the pulsation cycle of the very large amplitudeβ Cephei star BW Vul with optical and UV (IUE) spectra, as well asoptical photometry. The FUSE light curve suggests a temperatureamplitude of about 4000 K, while the radial velocity curve is similar tocorresponding optical curves, except that the famous ``stillstand''feature, due to a shock wave caused by returning infall to theatmosphere from a previous cycle, is slightly weakened. We haveperformed line syntheses on a number of features in various spectralregions. We find that profiles of the red He I lines (λ6678 andλ5876) at ``faint star'' and ``bright star'' phases can besynthesized with standard Kurucz model atmospheres by assuming moderateand high microturbulences, respectively. For the faint-star profile, theline profiles are too deep to be explained other than by lowering theboundary temperature of a standard Kurucz model by 1000-2000 K. Thisresult is confirmed by line syntheses of the far-UV spectra at bothphases, which show that fits can be best achieved with models havingeffective temperatures 4000 K hotter than models fitting optical lines.This result is robust against non-LTE effects. The combined optical andfar-UV results suggest that the temperature distributions of both thelower and upper atmosphere are steeper than those computed in (static)Kurucz models. With ad hoc modifications to the atmospheric temperaturedistribution, we simulated the weakening of the temperature-sensitive CII λλ6578-6583 doublet during shock passages byintroducing a uniform shallow temperature gradient through the lineformation region. This result agrees with published hydrodynamic resultsthat these shocks produce a plateau-like elevation in gas variablesthrough the atmosphere.
| Period Changes of BW Vulpeculae: the Influence of Motion in a Binary System
This paper presents the reduced photoelectric observational data on thevariable star BW Vulpeculae obtained at Timisoara AstronomicalObservatory. Using the moments of the observed minima and others fromreferences, we computed a quadratic ephemeris describing a secularevolution. Removing the evolutionary term, from the O-C diagram, itstill remains a periodicity. Assuming this due to the light-time effectin a binary system, these residuals allowed us to compute the orbitalelements. Finally we concluded that the period variation is described bythe superposition of two separate physical effects: the evolution of thepulsating star and the orbital motion in a binary system.
| 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.
| Photoelectric photometry of the Beta Cephei star BW Vulpeculae (1988-1991)
BW Vul, the Beta Cephei star with the largest-known amplitude, has beenobserved through several cycles of pulsation. The data, obtained atthree observatories, were homogenized, and are presented in tabularform. Times of minimum and maximum light were derived, and acontemporary value for the period is deduced. Our data do not reveal anysudden period change in the time span 1988-1991.
| Time of Light Minimum of BW Vulpeculae
Not Available
| A Photometric Analysis of Bw-Vulpeculae
Not Available
| Research Note - Absolute UBV Photometry at the Zacatecas Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985RMxAA..11...55S&db_key=AST
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