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Properties and nature of Be stars. XXI. The long-term and the orbital variations of V832 Cyg = 59 Cyg
An analysis of numerous homogenized UBV photoelectric observations andred spectra of the Be star V832 Cyg from several observatories led tothe following principal findings: 1. Pronounced long-term light andcolour variations of V832 Cyg result from a combination of two effects:from the gradual formation of a new Be envelope, and from an asymmetryand a slow revolution of the envelope (or its one-armed oscillation).The colour variations associated with the envelope formation arecharacterized by a positive correlation between brightness and emissionstrength, typical for stars which are not seen roughly equator-on. 2.The V magnitude observations prewhitened for the long-term changesfollow a sinusoidal orbital light curve with a small amplitude and aperiod of 28.1971d which is derived from observations spanning 43 years.This independently confirms a 12-year old suggestion that the star is aspectroscopic binary with a 29-d period. V832 Cyg thus becomes the fifthknown Be star with cyclic long-term V/R variations, the duplicity ofwhich has been proven, the four other cases being ζ Tau, V923 Aql,γ Cas and X Per. Therefore, the hypothesis that the long-term V/Rvariations may arise due to the attractive force of the binary companionat certain phases of the envelope formation is still worth consideringas a viable alternative to the model of one-armed oscillation. 3. Wehave shown that the RV and V/R variations of the Hα and He I 6678emission lines are all roughly in phase. In particular, the He I 6678emission also moves with the Be primary which differs from what wasfound for another Be binary, \varphi Per. 4. We derived the orbitalelements and found that in spite of the remaining uncertainties, thebasic physical properties of the 28.2d binary are well constrained. 5.The light minimum of the orbital light curve occurs at elongation whenthe Be star is approaching us and the object becomes bluest in (B-V) andreddest in (U-B) at the same time. This may indicate that a part of theoptically thick regions of the envelope is eclipsed at these orbitalphases. Guest investigator, Dominion Astrophysical Observatory, HerzbergInstitute of Astrophysics, National Research Council of Canada. Alsobased on observations from Castanet-Tolosan, Hvar, Ondřejov,Pic-du-Midi, Rozen, San Pedro Mártir, Toronto and Xing-LongObservatories and on photoelectric photometry by AAVSO members. Tables3, 5-7 are 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/387/580}
| Properties and nature of Be stars. XIX. Spectral and light variability of 60 Cygni
An analysis of electronic spectra secured between 1992 and 1999 at theHaute Provence, Ondřejov and Dominion Astrophysical Observatoriesand of differential UBV measurements of 60 Cyg obtained between 1984 and1999 at Hvar, San Pedro Mártir, Toronto and XinglongObservatories, the all-sky Hipparcos satellite H_p photometrytransformed to Johnson V and B magnitudes, and all-sky UBV observationspublished by several authors and dating back to fifties, led to thefollowing findings: 1. 60 Cyg exhibits pronounced long-term spectralvariations characterized by the B -> Be -> B phase transitions.These long-term spectral changes of 60 Cyg are also accompanied bycorresponding, though rather mild, secular light and colour variations.The character of these variations is indicative of a positivecorrelation between the brightness and emission-line strength. 2. NLTEmodel atmosphere analysis of spectra secured during the quiescence state(B phase) of 60 Cyg shows that the star has overabundance of helium.Best results were obtained for N_He/N_H= 0.2. 3. The presence ofperiodic medium-term changes, with a period of 146.6 d +/- 0.6 d wasfound in the radial-velocity of the Hα He I 4471 Å lines. Ifconfirmed by future observations, these variations could indicate that60 Cyg is a spectroscopic binary. 4. There are clear rapid periodicline-profile changes of (a) overall line asymmetry, and (b) weaksub-features passing across the line profiles every about 0.1 d. Theradial velocity and asymmetry of He I lines vary with a period of 1.0647d and a double-wave curve. There is no evidence of this period inphotometry, however. 5. The rapid light variations of 60 Cyg aredominated by rapid changes with a full amplitude of almost 0.1 m. Aperiod analysis of V magnitude data prewhitened for the long-termchanges indicates a period of 0.2997029 d, reported earlier. The mostinteresting finding is that also all recorded series of movingsub-features in the line profiles can be reconciled with this period:the sub-features reappear at the same phase intervals of the 0.2997 dperiod in the line profiles over an interval of several years.Considering the acceleration of these sub-features, 1900 km s^{-1}d^{-1}, it is conceivable that the true physical (super) period of thesechanges is either 0.8991 d or 1.1988 d. 6. The findings mentioned inpoints 4 and 5 represent a challenge for the NRP scenario since thelight changes would be dominated by a high-order mode instead of alow-order one.
| Photometry from the HIPPARCOS Catalogue: Constant MCP Stars, Comparison and Check Stars
Photometry from the Hipparcos catalogue is used to verify the constancyof four magnetic CP stars, as well as the comparison and the check starsused for variability studies of normal and chemically peculiar B and Astars with the Four College Automated Photoelectric Telescope;variability in these stars can produce spurious results. A few of thecomparison stars are found to be variable and should be replaced forfuture differential photometric studies.
| UBV photometry of Be stars at Hvar: 1972--1990
A summary of results of the systematic UBV photoelectric monitoring ofbright northern Be stars carried out at the Hvar Observatory between1972 and 1990 is presented. Altogether, 76 Be stars of all luminosityclasses were observed and 13,848 UBV measurements secured.Simultaneously, 9,648 UBV measurements of 48 check stars (most of themof early spectral types) were obtained. A careful transformation of allobservations into the standard Johnson system allowed detection andmonitoring of even very mild long-term light and colour variations ofthese objects. Almost all early-type Be stars in the sample turned outto be variable. For several stars phase-locked light variations relatedto their binary nature were established. Sudden brightenings, on a timescale of a few days, were detected for o Cas and QR Vul. Tables 2 and 3are only available in electronic form at CDS via ftp tocdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
| Stromgren UVBY photometry of the magnetic Chemically Peculiar stars HD 32633, 25 Sex, HR 7224, and HD 200311
Differential Stromgren uvby photometric observations from the FourCollege Automated Photoelectric Telescope refine the rotational periodsand define the shapes of the light curves of four magnetic ChemicallyPeculiar stars. HD 32633 (P = 6.43000 d) exhibits an in-phasevariability with asymmetrically shaped light curves. 25 Sex (P = 4.37900d) has a complex variability with the v, b, and y light variabilitycrudely in phase, but quite different from that of u. HR 7224 (P =1.123095 d) shows in-phase variability with two nearly equal secondaryminima. HD 200311 (P = 26.0042 d), which was previous thought to be along period variable, is found to be a modest photometric variable.Tables 2 to 5 only in electronic form at CDS via ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html.
| Be Stars in the AAVSO Photoelectric Photometry Program
We present light curves, and an analysis of periodicity, for the threeBe stars in the AAVSO Photoelectric Photometry Program for which thereare adequate data. V2048 Ophiuchi was variable by 0.2 magnitude beforeJD 2447900, but has been constant, at minimum, since. V832 Cygni hasvaried quasi-cyclically by 0.1 magnitude over the period of observation.EW Lacertae showed a broad minimum, 0.2 magnitude deep. The spacing ofthe observations is not well suited for investigating the short-termvariations of these stars.
| 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.
| Reliable photometric reductions to the standard UBV (or uvby) system and accurate UBV magnitudes of bright standard stars from the northern part of the international Be program
A modified method of computer reduction of UBV (or uvby) photoelectricobservations to standard systems, which combines advantages of what hasso far been achieved in this area, is described in detail. A completereduction of over 46000 UBV observations obtained at Hvar Observatorybetween 1972 and 1991, and of nearly 5000 UBV observations secured atSkalnate Pleso Observatory between 1980 and 1987, was carried out usingthe new technique. It is argued that replacing the original Johnson'sUBV values for the non-variable stars that were observed by the meanvalues based on repeated observations over several years and applyingthe new reduction technique can ensure a stable reproduction of UBVmagnitudes, obviously quite close to the standard Johnson's ones, overmany years and from observatories situated at very different altitudesabove sea level within about 0.01mag in all three UBV magnitudes. A listof new accurate mean UBV values of 191 stars which were regularlyobserved at Hvar - and a part of them also at Skalnate Pleso - ascomparison, check and standard stars in the Be- and Ap-star observingprograms, is included for future use by photometric observers in theNorthern Hemisphere. For a number of these stars, we can guaranteesecular constancy within 0.mag01 during the past 5 to 15 years.
| An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| Photoelectric Photometry of Stars in the Vilnius System in the Area of the North America and Pelican Nebulae
Not Available
| Be Variable 59 Cyg: Rapid Light Variations Detected
Not Available
| Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
| Photoelectric monitoring of bright Be stars
The paper describes and summarizes BV photometric observations of 34bright, active Be stars made at various times between 1981 and 1987 witha 0.4-m telescope at the University of Toronto. These observationsdemonstrate the photometric variability of Be stars on time scales ofhours to years.
| Spectral types of 80 early-type stars of variable radial velocity
MK spectral types are given for 80 normal early-type stars of variableradial velocity. These spectral types were determined from spectrogramstaken with the Lick Observatory 0.9-m refractor during the years1957-58.
| 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
| The S201 far-ultraviolet imaging survey. II - A field in Cygnus
Far-ultraviolet imagery of a region in Cygnus, a 20 deg diameter fieldcentered near (1950) R. A. 21 h 31.2 m decl. +37 deg 25 arcmin, wasobtained by the S201 far-ultraviolet camera during the Apollo 16mission. In a 10 minute exposure covering the 1250-1600 A wavelengthrange (effective wavelength 1400 A), 730 star images can be detected,corresponding to a limiting ultraviolet magnitude of about m (1400) =10. Assuming nominal interstellar extinction values in this region nearthe galactic plane, this result corresponds to the detection of A0 Vstars to a distance of 300 pc and of B0 V stars to 1500 pc.Uncertainties in spectral classification and interstellar extinction forindividual objects are probably more significant than calibration ormeasurement errors. Most of the objects detected are identified withstars in the Smithsonian Astrophysical Observatory Star Catalog (1966),or the Catalog of Stellar Identifications (1979) or both, but 87 objectsremain unidentified (or are identified with late-type stars).
| Photometry of V1057 CYG and neighboring stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975PASP...87..379L&db_key=AST
| La mesure des vitesses radiales au prisme objectif. XII. 5ème Liste de vitesses radiales déterminées au prisme objectif à vision directe
Not Available
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