New Times of Minima of Some Eclipsing Variables
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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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A catalogue of eclipsing variables
A new catalogue of 6330 eclipsing variable stars is presented. Thecatalogue was developed from the General Catalogue of Variable Stars(GCVS) and its textual remarks by including recently publishedinformation about classification of 843 systems and making correspondingcorrections of GCVS data. The catalogue1 represents thelargest list of eclipsing binaries classified from observations.
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New Times of Minima of Some Eclipsing Variables
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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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Photoelectric Minima of Some Eclipsing Binary Stars
We present 70 minima times of 35 eclipsing binaries.
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Times of Minima of Eclipsing Binary Stars
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uvbyβ Photometry of Selected Eclipsing Binary Stars
New uvbyβ observations of 51 eclipsing binary stars are presented,and outside-eclipse averages for 45 of them are given. Many of thesebinaries are detached main-sequence pairs that have been discovered tobe double-lined spectroscopic binaries and appear suitable fordeterminations of accurate absolute dimensions and masses. Photometricproperties are recomputed for 14 of the binaries, for which absoluteproperties have been published previously. Intercomparisons are madewith previous photometry, when available, and notes are given for someindividual systems.
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Times of Minima of Eclipsing Binaries
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Times of Minima of Eclipsing Binaries
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On X-Ray Variability in Active Binary Stars
We have compared the X-ray emissions of active binary stars observed atvarious epochs by the Einstein and ROSAT satellites in order toinvestigate the nature of their X-ray variability. The primary aim ofthis work is to determine whether or not active binaries exhibitlong-term variations in X-ray emission, perhaps analogous to theobserved cyclic behavior of solar magnetic activity. We find that, whilethe mean level of emission of the sample remains steady, comparison ofdifferent ROSAT observations of the same stars shows significantvariation on timescales <~2 yr, with an ``effective variability''ΔI/I=0.32+/-0.04, where I and ΔI represent the mean emissionand variation from the mean emission, respectively. A comparison of theROSAT All-Sky Survey and later pointed observations with earlierobservations of the same stars carried out with Einstein yields onlymarginal evidence for a larger variation (ΔI/I=0.38+/-0.04 forEinstein vs. ROSAT All-Sky Survey and 0.46+/-0.05 for Einstein vs. ROSATpointed) at these longer timescales (~10 yr), thus indicating thepossible presence of a long-term component to the variability. Whetheror not this long-term component is due to the presence of cyclicvariability cannot be decided on the basis of existing data. However,assuming that this component is analogous to the observed cyclicvariability of the Sun, we find that the relative magnitude of thecyclic component in the ROSAT passband can, at most, be a factor of 4,i.e., I_cyc/I_min<4. This is to be compared with the correspondingbut significantly higher solar value of ~10-10^2 derived from GOES,Yohkoh, and Solrad data. These results are consistent with thesuggestions of earlier studies that a turbulent or distributive dynamomight be responsible for the observed magnetic activity on the mostactive, rapidly rotating stars.
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A Spectroscopic Survey of Late F--K Eclipsing Binaries
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJS..106..133P&db_key=AST
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The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
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Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
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Predicting the Secondary Minima Depths and Spectra of the Main Components for the Dm-Type Eclipsing Variable Stars
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A catalog of chromospherically active binary stars (second edition)
The catalog contains 206 spectroscopic binary systems with at least onelate-type component that shows Ca II H and K emission in its spectrum.These systems include the classical RS CVn binaries and BY Dra binaries.The catalog summarizes information on the photometric, spectroscopic,orbital, and physical properties of the systems as well as space motionsand positions. Up to 42 'parameters' for each stellar system are listedfollowed by the appropriate reference to direct interested colleagues tothe original papers. A comprehensive selection of further informationfor each star is given in the individual notes. In addition, the catalogcontains a candidate list of 138 stars that have similar characteristicsbut are not definitely known binaries or have not had Ca II H and Kemission observed.
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Radio continuum and X-ray properties of the coronae of RS Canum Venaticorum and related active binary systems
Data from circular polarization measurements are reported which yieldradio-continuum and X-ray characterizations of the coronae of activebinaries including RS CVn. The circular polarization measurements aretaken at 6 cm for 28 binary systems detected at flux densities of morethan 0.7 mJy, and the data are examined in conjunction with those byDrake et al. (1989). Optical positions are derived for 8 RS CVn objects,three previous detections are confirmed, and seven sources are shown tohave circular polarization at levels of 2-13 percent. A total of 49X-ray sources are confirmed in a total of 190 positions, and thecorrelation between X-ray and radio emissions is analyzed. Noobservational evidence exists to support the notion that radio and X-rayemissions are due to nonthermal electrons, and the data provide evidencefor and against thermal gyrosynchrotron radio emission.
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UBV photometry of selected eclipsing binary stars
The study reports new UBV observations of 69 eclipsing binary stars andprovides outside-eclipse averages. Revised photometric properties offive of the binaries, for which absolute properties were publishedpreviously, are computed. Comparisons are made with previous photometry,when available, and notes are given for some individual systems.
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A radio survey of weak T Tauri stars in Taurus-Auriga
A multi-epoch 5 GHz survey of candidate or confirmed weak T Tauri starsin the Taurus-Auriga molecular cloud complex was conducted with the VeryLarge Array. The stars were chosen from those having detectable X-ray orchromospheric emission, and weak-emission-line pre-main-sequence starsfound by other means. Snapshots of 99 VLA fields containing 119candidate stars were obtained with a sensitivity of 0.7 mJy; most fieldswere observed on two or three dates. Nine radio sources coincident withcataloged stars were found. One may be an RS CVn binary system; theother eight are pre-main-sequence stars. Three of the detected stars -HD 283447, V410 Tau, and FK X-ray 1 - were previously known radiosources. Five new detections are Herbig's Anon 1, Hubble 4, HDE 283572,Elias 12, and HK Tau/c. At least five of the sources are variable, andno linear or circular polarization was found. Several lines of evidencesuggest that the radio-detected weak T Tauri stars are quite young,perhaps younger on average than nondetected stars.
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An X-ray survey for pre-main-sequence stars in the Taurus-Auriga and Perseus molecular cloud complexes
Seventy-five fields from the Einstein X-Ray Observatory IPC detectorbetween 3h and 5h right ascension and 15 deg and 35 deg declination areexamined to search for X-ray-emitting low-mass pre-main-sequence (PMS)stars. Six such stars were previously found; they appear to be similarto T Tauri stars but without dense circumstellar envelopes or winds.Finding charts are presented for 59 X-ray sources that may be PMS stars.While some are likely to be spurious X-ray sources, chance coincidenceswith unrelated stars, or non-PMS stellar sources such as RS CVn typebinaries, approximately half are probably X-ray-selected PMS stars.
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A survey for transient accretion disks in short-period Algol systems. II
Time-resolved spectroscopy during primary eclipse was utilized in orderto search for emission lines from accretion disks surrounding theprimary component in short-period Algol systems. The results ofobservations of 46 systems surveyed during 80 eclipses are presented.For disks in long-period systems, the gas stream from the secondary starmoves around the trailing hemisphere of the primary and forms apermanent disk. However, in short-period systems the gas stream strikesthe primary star. Disks formed by this latter process are found to betransient and unstable. The discovery of two new transient disk systemsis reported: RW Mon and RR Dra. When the relative radius of the primarystar is plotted versus mass ratio, the systems with permanent disks,transient disks, and without disks segregate into three distinct regionsof the plot. This implies that the differences between systems withtransient disks and those without disks may be simply a matter of thelocation of the stream impact on the primary star.
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A catalogue of parameters for eclipsing binaries
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Visual minima of eclipsing binaries from Cracow observations in 1920-1950.
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Strömgren four-colour observations of Northern Hemisphere binary systems
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Ephemerides of eclipsing stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963AJ.....68..257W&db_key=AST
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The Light-curves of Eclipsing Binaries
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77 neue Veräderliche
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