Contents
Images
Upload your image
DSS Images Other Images
Related articles
Radial Velocity Studies of Close Binary Stars. XI.
Radial-velocity measurements and sine-curve fits to orbital radialvelocity variations are presented for 10 close binary systems: DU Boo,ET Boo, TX Cnc, V1073 Cyg, HL Dra, AK Her, VW LMi, V566 Oph, TV UMi, andAG Vir. With this contribution, the David Dunlap Observatory program hasreached the point of 100 published radial velocity orbits. The radialvelocities have been determined using an improved fitting technique thatuses rotational profiles to approximate individual peaks in broadeningfunctions. Three systems, ET Boo, VW LMi, and TV UMi, are found to bequadruple, while AG Vir appears to be a spectroscopic triple. ET Boo, amember of a close visual binary with Pvis=113 yr, waspreviously known to be a multiple system, but we show that the secondcomponent is actually a close, noneclipsing binary. The new observationshave enabled us to determine the spectroscopic orbits of the companion,noneclipsing pairs in ET Boo and VW LMi. A particularly interesting caseis VW LMi, for which the period of the mutual revolution of the twospectroscopic binaries is only 355 days. While most of the studiedeclipsing pairs are contact binaries, ET Boo is composed of twodouble-lined detached binaries, and HL Dra is a single-lined detached orsemidetached system. Five systems of this group have been observedspectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-linedbinary), V566 Oph, and AG Vir, but our new data are of much higherquality than in the previous studies.Based on data obtained at the David Dunlap Observatory, University ofToronto, Canada.
| 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.
| Key parameters of W UMa-type contact binaries discovered by HIPPARCOS
A sample of W UMa-type binaries which were discovered by the HIPPARCOSsatellite was constructed with the aid of well defined selectioncriteria described in this work. The selection process showed up thatseveral systems of which the variability types have been assigned as EBin HIPPARCOS catalogue are genuine contact binaries of W UMa-type. Thelight curves of the 64 selected systems based on HIPPARCOS photometrywere analyzed with the aid of light curve synthesis method by Rucinskiand their geometric elements (namely mass ratio q, degree of contact f,and orbital inclination i) were determined. The solutions were obtainedfor the first time for many of the systems in the sample and would be agood source for their future light curve analyses based on more precisefollow-up observations.Based on observations made with the ESA HIPPARCOSastrometry satellite.
| The 7.5 Magnitude Limit Sample of Bright Short-Period Binary Stars. I. How Many Contact Binaries Are There?
A sample of bright contact binary stars (W UMa type or EW, and related:with β Lyr light curves, EB, and ellipsoidal, ELL-in effect, allbut the detached, EA) to the limit of Vmax=7.5 mag is deemedto include all discoverable short-period (P<1 day) binaries withphotometric variation larger than about 0.05 mag. Of the 32 systems inthe final sample, 11 systems have been discovered by the Hipparcossatellite. The combined spatial density is evaluated at(1.02+/-0.24)×10-5 pc-3. The relativefrequency of occurrence (RFO), defined in relation to the main-sequencestars, depends on the luminosity. An assumption of RFO~=1/500 forMV>+1.5 is consistent with the data, although the numberstatistics is poor with the resulting uncertainty in the spatial densityand the RFO by a factor of about 2. The RFO rapidly decreases forbrighter binaries to a level of 1/5000 for MV<+1.5 and to1/30,000 for MV<+0.5. The high RFO of 1/130, previouslydetermined from the deep OGLE-I sample of disk population W UMa typesystems toward Baade's window, is inconsistent with and unconfirmed bythe new results. Possible reasons for the large discrepancy arediscussed. They include several observational effects but also apossibility of a genuine increase in the contact-binary density in thecentral parts of the Galaxy. Based on data from the Hipparcos satellitemission and from the David Dunlap Observatory, University of Toronto.
| 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
| On Identifications of New Variable Stars Announced by Woitas
Confusion in the positions of variable stars announced in IBVS No. 4444has been clarified.
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| Detection of 43 New Bright Variable Stars by the TYCHO Instrument of the HIPPARCOS Satellite
Not Available
| Transformation equations and other aids for VRI photometry
Transformations among VRI systems are commonly beset by Paschen-jumpeffects, for which fully satisfactory allowance has not previously beenmade. This paper describes two new techniques which are based on thework of Gutierrez-Moreno, and which allow fully for the effects of thePaschen jump. Values of E(V-R)/E(B-V) and E(R-I)/E(B-V) are also givenfor the Cousins system for a wide range of temperatures. These and thenew techniques contribute to a set of new transformation relations whichapply for most VRI systems; the status of the remaining systems isreviewed, and future work needed for them is described. Two majorsources of Cousins VRI data underlie the new relations; the consistencyof these sources is reviewed and found to be generally satisfactory,although more work on this question is needed. Finally, three tables oftransformed standard-star and other data are given for the Cousins andJohnson systems, and a description of ways to reproduce the latter ispresented.
| Red and infra-red magnitudes and colours for 300 F. G and K type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967MNRAS.135...23A&db_key=AST
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Dragon |
| Right ascension: | 18h34m26.30s |
| Declination: | +57°48'06.6" |
| Apparent magnitude: | 7.366 |
| Distance: | 156.495 parsecs |
| Proper motion RA: | -15.2 |
| Proper motion Dec: | -5.7 |
| B-T magnitude: | 7.608 |
| V-T magnitude: | 7.386 |
Catalogs and designations:
|
