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An improved ephemeris and physical elements of ER Vul
New photoelectric U B{V} and BV RI observations, secured duringAugust-November of 2002 at two observatories distant in local time areanalyzed together with two earlier photometric data sets and allavailable radial velocities to derive the most accurate ephemeris of thebinary and to set limits on its basic physical elements. Theseobservations were obtained as a support for a high-dispersionspectroscopic study, results of which will be published separately. Itwas found that radial velocities and photometric observations spanning53 years can be reconciled with the linear ephemeris T_prim.min.=HJD 2440 182.25628(46) + 0698095113(29)d × E, where the rms errors ofthe last digits are given in brackets. Masses of the stars are 1.02 \fmsand 0.97 \fms and the binary separation is 4.170 Rȯ.There is still a large uncertainty in the stellar radii. We also reportthe discovery of rapid light variations on a time scale of hours seen inthe U band light curve and offer a few thoughts on the futureinvestigation of this binary.This research is based on photoelectric observations from Hvar andUniversity of Victoria Observatories.Table 4 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/415/289
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| The active close binary system ER Vulpeculae
UBV (RI)c photometry of the short period RS CVn binary ERVul, gathered in the years 1990-1992, is analyzed. A set of binarysystem parameters is finally derived with some confidence, after duetests and comparisons with literature values. The well-knownirregularities of ER Vul are interpreted largely in terms of darkmaculae, whose major characteristics (size, surface position) arequantified. The occurrence of at least one bright spot (facula) is alsoevidenced, however. The maculation representation is shown to beconsistent with a 'quasi-poloidal' spot distribution - high latitudespot concentrations tending to be roughly symmetric in both hemispheres.This model requires further observational checking.
| UBV photometry of ER Vulpeculae
UBV photometry of the RS CVn-type eclipsing binary system ER Vulpeculaehas been presented. The period comes out to be 0.698093d. The averagedepths of primary and secondary minima are, respectively, 0.21 and0.12m. The colors at various phases have been given. A dip is seenaround phase 0.73P as was seen in the observations of Arevalo et al.(1988). Large scatter is present in the observations as noticed earlier,and may be due to activity of the components.
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