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The observational status of the Slowly Pulsating B star iota Herculis
New spectroscopic and photometric measurements are presented concerningthe SPB binary star iota Her. Our observations are spread over 10 years,and consist of 10 spectroscopic nights in 1985, 7 spectroscopic nightsand 22 photometric nights in 1987, and 15 spectroscopic nights in 1995.In addition, we analysed the photometric observations provided byHipparcos (1990-1993) as well as all published radial velocities. Weused all the spectroscopic data to refine the binary ephemeris. It wastherefore possible to study the pulsation variability properly. Despiteour large data set, only one frequency has been clearly established: nu1=0.28671 c.d-1, for which an ephemeris isprovided. Three other frequencies are detected: nu 2=0.43c.d-1, nu 3=0.77 c.d-1 and nu4=0.2483 c.d-1. The nu 2 frequency ispresent in most data sets, nu 4 is detected only in Hipparcosdata (longtime basis of homogeneous data set), while nu 3 isdetected in only one data set. The precision on the value of nu1 allowed us to estimate the phase-lag between photometricand spectroscopic variations for the first time in an SPB star. The lagof the photometric maxima with respect to those of velocity is around0.64 period i.e., significantly different from what is measured in theclasses of variable stars surrounding the SPB stars. The pulsationamplitude has varied in a complex way during the last 10 years. It hasincreased during the 3 years of photometric observations by Hipparcos,while a decrease by a factor 2 was observed in spectroscopic databetween 1985 and 1995. Periodograms of both photometric andspectroscopic variations show faint peaks in the [6;8] c.d-1and [15;25] c.d-1 frequency regions. However, one of our datasets, providing a good precision on the velocity variations, shows arather flat periodogram after 5 c.d-1, with no detectablepeak having an amplitude above 0.05 km s-1. Therefore, theserelatively high frequencies may have a transient nature. Although iotaHer is one of the best observed SPB star, its variability behaviour isstill uncertain, and long term monitoring is needed. Partially based onobservations obtained at the Observatoire de Haute Provence
| 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.
| Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | הרקולס |
| התרוממות ימנית: | 17h44m04.31s |
| סירוב: | +45°02'04.9" |
| גודל גלוי: | 6.734 |
| מרחק: | 164.204 פארסק |
| תנועה נכונה: | -1.4 |
| תנועה נכונה: | 15.9 |
| B-T magnitude: | 6.696 |
| V-T magnitude: | 6.731 |
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