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Radial Velocity Studies of Close Binary Stars. XII.
Radial velocity measurements and sine-curve fits to the orbital radialvelocity variations are presented for 10 close binary systems: OO Aql,CC Com, V345 Gem, XY Leo, AM Leo, V1010 Oph, V2612 Oph, XX Sex, W UMa,and XY UMa. Most of these binaries have been observed spectroscopicallybefore, but our data are of higher quality and consistency than in theprevious studies. While most of the studied eclipsing pairs are contactbinaries, V1010 Oph is probably a detached or semidetached double-linedbinary, and XY UMa is a detached, chromospherically active system whosebroadening functions clearly show well-defined and localized dark spotson the primary component. A particularly interesting case is XY Leo,which is a member of visually unresolved quadruple system composed of acontact binary and a detached, noneclipsing, active binary with an 0.805day orbital period. V345 Gem and AM Leo are known members of visualbinaries. We found faint visual companions at about 2"-3" from XX Sexand XY UMa.Based on data obtained at the David Dunlap Observatory, University ofToronto.
| Measurement of Double Stars with a CCD Camera: Two Methods
This research aims to determine ρ and θ for double starsusing equatorial coordinates. Thisapproach offers several advantages. Acomparison of the derived values with those from traditional measures ofrectangular coordinates for the same images shows the results areequivalent. Measures for 62 double stars have been determined.
| Light-time effect in the eclipsing binary system AM Leonis
We report four new times of minimum light and the improved ephemeris forthe well known contact binary AM Leo. The O-C diagram, constructed withall reliable timings found in the literature was analyzed and the thelight-time effect in the system was confirmed. We found a periodicity of44.82 years in the O-C residuals with an amplitude of 0.0058 day. Theperiodic curve representing the O-C values is asymmetric indicating alarge eccentricity of 0.73 of the third body orbit. The mass of thethird body is found to be 0.175 Msun for the orbitalinclination of the eclipsing pair's orbit.
| New Light Curves and Orbital Solution for AM Leonis
New UBVRI photometry has been obtained for the W UMa eclipsing system AMLeonis. The data have been used to derive nine times of minimum and toconstruct light curves. The minimum timings show that the systemrecently had a significant period increase. Modeling of the light curvesshows AM Leo to be an overcontact system with a mass ratio of 2.51. BothRucinski & Duerbeck's absolute magnitude calibration for W UMa starsapplied to our photometry and the radial velocity curve combined withour derived parameters indicate a distance near 125 pc, larger than the77 pc from the Hipparcos parallax.
| The Hamburg/RASS Catalogue of optical identifications. Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources
We present the Hamburg/RASS Catalogue (HRC) of optical identificationsof X-ray sources at high-galactic latitude. The HRC includes all X-raysources from the ROSAT Bright Source Catalogue (RASS-BSC) with galacticlatitude |b| >=30degr and declination delta >=0degr . In thispart of the sky covering ~ 10 000 deg2 the RASS-BSC contains5341 X-ray sources. For the optical identification we used blue Schmidtprism and direct plates taken for the northern hemisphere Hamburg QuasarSurvey (HQS) which are now available in digitized form. The limitingmagnitudes are 18.5 and 20, respectively. For 82% of the selectedRASS-BSC an identification could be given. For the rest either nocounterpart was visible in the error circle or a plausibleidentification was not possible. With ~ 42% AGN represent the largestgroup of X-ray emitters, ~ 31% have a stellar counterpart, whereasgalaxies and cluster of galaxies comprise only ~ 4% and ~ 5%,respectively. In ~ 3% of the RASS-BSC sources no object was visible onour blue direct plates within 40\arcsec around the X-ray sourceposition. The catalogue is used as a source for the selection of(nearly) complete samples of the various classes of X-ray emitters.
| Photovisual Magnitude Differences for 169 Double Stars
Photovisual magnitude differences determined from multi-exposurephotographic plates for 169 double stars are presented. The separationsrange from 1.5'' to 113\arcsec, and the photovisual magnitudedifferences vary from 0.03 to 6.14 magnitudes. The internal mean errorof a single magnitude difference estimate is +/-0.064 magnitude.
| Photographic astrometry of binar and proper-motion stars: 8.
300 trigonometric parallaxes, 15 revised binary-star orbits, and 24 massratios are listed and annotated.
| CCD astrometry and instrumental Delta-V photometry of wide visual double stars. III - Differential measurements of often observed southern pairs
We present accurate relative positions and instrumental visual (BesselV) magnitude differences of southern wide star components. The meanaccuracy of the angular separation is 0.02 arcsecs, which corresponds to1.5 micron on the CCD chip, and of magnitude difference 0.007mag/exposure. The program pairs are targets of the HIPPARCOS mission andthey have been observed at least four times in the last 150 yrs.
| Multiple systems of astrophysical interest. III - When is a binary wide?
The possibility that the statistics of wide binaries, used to testtheories of stellar encounters, are biased against large separations isexamined on the basis of known widely spaced systems of objects withcommon space motion. It is possible to conclude that before concepts ofstellar interactions can be quantized both unbiased samples of widebinaries and some knowledge of their ages are necessary.
| Contact binaries, II.
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Observation and Astrometry data
| Constellation: | Leo |
| Right ascension: | 11h02m10.11s |
| Declination: | +09°53'42.8" |
| Apparent magnitude: | 11.015 |
| Proper motion RA: | -12 |
| Proper motion Dec: | -33.4 |
| B-T magnitude: | 11.611 |
| V-T magnitude: | 11.065 |
Catalogs and designations:
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