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A Timing Model for the RR Lyrae Variable Star TU Ursae Majoris, a Probable Member of a Binary System
The epochs of maximum light (EMLs) in the light curve of TU UMa, a haloRR Lyrae variable star, depart from a linear ephemeris over the 85 yrinterval that the star has been under scrutiny. We have supplemented thelist of EMLs assembled by Saha & White with new photoelectric(photomultiplier tube or CCD) measurements made during the period1990-1999 in addition, we have collected other recent EMLs from theliterature. There are now 83 EMLs in the list, of which 35 are reportedfor the first time here. We analyze these data, combining a quadraticpulsation ephemeris with an orbital timing model, as previouslysuggested by Szeidl et al. and by Saha & White. The favored modelrelies exclusively on photoelectric measurements of EMLs, and it yieldsresiduals (2.4 minutes rms) that are comparable to the precision ofmeasurement. We conclude that TU UMa is a member of a binary star systemwith a period of approximately 23 yr. This conclusion is supported byavailable high-quality center-of-mass radial velocity data. The inferredorbit is highly eccentric, e~0.79, but not extremely so. The minimummass of the companion object in the favored model is ~0.4Msolar. The minimum projected size of TU UMa's orbital majoraxis is 10 mas. The binary system is presently near its widest orbitaland angular separation. TU UMa is the only RR Lyrae star that can beconsidered with high probability to be a member of a relativelyshort-period binary and as such is the only RR Lyrae star for whichthere is a prospect for direct measurement of the mass.
| 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.
| The luminosity scale of RR Lyrae stars with the Baade-Wesselink method. I - Photometry and radial velocities
UBVRI optical and JK IR photometry and radical velocities are presentedfor a sample of 13 field RR Lyrae stars with metallicities ranging frommetal-rich to metal-poor. These stars include 11 ab-type variables, SWAnd, RR Cet, SU Dra, Rx Eri, RR Gem, RR Leo, TT Lyn, AV Peg, AR Per, TUUMa, and UU Vir, and two c-type variables, TV Boo and T Sex. Light,color, and radial velocity curves of these RR Lyrae stars are alsopresented in the paper.
| Photoelectric photometry of stars near the north Galactic pole. II
UBV photometric observations of about 700 stars near the north Galacticpole, obtained using single-channel photometers on the 40-cm and 60-cmCassegrain telescopes at Kvistaberg Observatory (during 1976-1983) andthe Spanish International Observatory (during 1984), respectively, aspart of a program including the stars to be observed by the Hipparcosspacecraft, are reported. The data are presented in a series of tablesand briefly characterized.
| La mesure des vitesses radiales au prisme objectif - X - 4e liste de vitesses radiales déterminées au prisme objectif à vision directe
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| A finding-list of stars of spectral type F2 and earlier in a north galactic pole region.
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| Bergedorfer Spektral-Durchmusterung der 115 noerdlichen Kapteynschen Eichfelder+Bd.3: Eichfeld 44 bis 67, Deklination +30 deg.
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Observation and Astrometry data
| Constellation: | Άρκτος Μεγάλη |
| Right ascension: | 11h27m42.49s |
| Declination: | +29°49'25.6" |
| Apparent magnitude: | 9.188 |
| Proper motion RA: | -45 |
| Proper motion Dec: | -27 |
| B-T magnitude: | 9.557 |
| V-T magnitude: | 9.219 |
Catalogs and designations:
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