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Period variations of the late type contact binaries YY ERI and AE Phe: How to use light curves outside minimum
We present and compare minimum times, computed for light curves of the WUma type binaries YY Eri and AE Phe. Two different methods are used: theLeiden method formulated by Kwee & van Woerden and the light curvesynthesis method developed by Wilson & Devinney. It is shown thatthe latter gives more and better information, and is even capable toextract the times of conjunction. Its application requires a completeanalysis of the parameters of the system, including the surfaceinhomogeneities. The observations are available in electronic form.
| Surface imaging of late-type contact binaries I: AE Phoenicis and YY Eridani
This paper presents the results of the first application of DopplerImaging to solar-type contact binaries. Our aim was to examine whetherthis technique can help discriminate between various types of surfaceinhomogeneities (dark vs. bright star-spots) which are produced bydifferent physical processes and which affect not only the surfacebrightness distribution but also the system's secular evolution.Simultaneous high dispersion spectroscopy and photometry for the systemsAE Phe and YY Eri were obtained at ESO using the Coude AuxiliaryTelescope (CAT) and the 50 cm telescope. The observed light-curves weresolved by means of the latest version of the Wilson-Devinney program.Doppler maps were constructed taking into account the effects of fastrotation and proximity of the system's components. Doppler maps revealthe presence of dark spots on both systems. For AE Phe, this result isin agreement with the light-curve solution. Indirect evidence ofenhanced chromospheric emission is also found. This emission appears tobe more intense on the primary components.
| Observations and analysis of the light curve of the WUMa system AE Phoenicis during 1975-1977
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1988A&A...189...89W&db_key=AST
| Hyades and Sirius supercluster members brighter than magnitude(V) 7.1. I - The first six hours of right ascension
This is the first of four papers listing the probable members of theHyades and Sirius superclusters among stars brighter than V = 7.1 mag.The star sample is contained in the Bright Star Catalogue and itsSupplement, augmented with a further supplement of 550 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 550 starsdiscussed here, as well as for all supercluster members.
| On the rarity of FK COM stars
Very high-dispersion spectra (2.5 A/mm) were obtained of 31 southernlate-type stars, predominantly early G giants, in an effort to find newrapidly rotating, active stars which would be FK Com-like. Measurementsof linewidths and the strength of chromospheric Ca II K-line emissionare presented, but no new star could be added to the class of 'rapidrotators'. Space densities and evolutionary lifetimes for FK Com starsare discussed.
| Estimation of spectral classifications for bright southern stars with interesting Stromgren indices
This paper investigates the degree of success with which uvby photometrycan be applied to predict spectral classifications for 947 A, F, and Gstars brighter than an apparent magnitude of 8.3 and with four-colorindices indicating some kind of interesting, unusual, or peculiarspectrum. One or several possible spectral classifications are estimatedfor each star from photometry alone, double stars are distinguished, andthe estimates are compared with published classifications. The resultsshow that the framework provided by uvby photometry can be extended toinclude most G and K stars, reddened stars, peculiar stars, and certaintypes of double star.
| Photometric study of AE Phoenicis
The bright W Ursae Majoris-type eclipsing binary system AE Phoenicis wasobserved with UBV filters during 1970 at the Cerro Tololo Inter-AmericanObservatory. A significant asymmetry in maximum light was observed andevidence for a small orbital eccentricity was detected. The eclipses arecomplete, and solutions of the light curves based on the Russell methodgive k equals 0.57.
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