Radial-velocity measurements and sine-curve fits to orbital radial velocity 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, and AG Vir. With this contribution, the David Dunlap Observatory program has reached the point of 100 published radial velocity orbits. The radial velocities have been determined using an improved fitting technique that uses rotational profiles to approximate individual peaks in broadening functions. Three systems, ET Boo, VW LMi, and TV UMi, are found to be quadruple, while AG Vir appears to be a spectroscopic triple. ET Boo, a member of a close visual binary with Pvis = 113 yr, was previously known to be a multiple system, but we show that the second component is actually a close, noneclipsing binary. The new observations have enabled us to determine the spectroscopic orbits of the companion, noneclipsing pairs in ET Boo and VW LMi. A particularly interesting case is VW LMi, for which the period of the mutual revolution of the two spectroscopic binaries is only 355 days. While most of the studied eclipsing pairs are contact binaries, ET Boo is composed of two double-lined detached binaries, and HL Dra is a single-lined detached or semidetached system. Five systems of this group have been observed spectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-lined binary), V566 Oph, and AG Vir, but our new data are of much higher quality than in the previous studies.
Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 and 2010 in the Taurus and Lupus star formation regions are presented. Using light-curve modelling under ...the assumption of internal invariability of spots, we obtained small values of the solar-type differential-rotation parameter (k = 0.0005-0.009) for three spotted weak-line T Tauri stars, V410 Tau, V987 Tau and Lupus 3-14; for another spotted weak-line T Tauri star (WTTS), Lupus 3-48, the data are consistent with a rigidly rotating surface (k = 0). Three flares of similar rise (4 min and 30 s) and decay (1 h and 45 min) times were detected in the light curve of Lupus 3-14. The brightness of the classical T Tauri star RY Tau continuously decreased over 3 weeks of its observations with a variable modulation not showing any obvious periodic signal.
DDO spectroscopic survey of MOST variable stars Pribulla, Theodor; Rucinski, Slavek M.; Kuschnig, Rainer ...
Monthly notices of the Royal Astronomical Society,
January 2009, Letnik:
392, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A spectroscopic support survey of 103 objects observed by the Microvariability and Oscillations of STars (MOST) satellite is presented; 96 are variable stars with 83 of them being new MOST ...variable-star detections or stars with variability types verified and/or modified on the basis of the MOST data. The analysis of 241 medium-resolution spectra using the broadening-function formalism yielded radial velocities, projected rotational velocities (for 31 targets for which it was possible) and spectral-type estimates. Seven new spectroscopic binaries were discovered; orbital solutions are given for two of them (HD 73709 and GSC 0814−0323). The visual binary HD 46180 was found to be composed of two close binary stars (eclipsing and non-eclipsing one), very probably forming a physical quadruple system.
The Broadening Functions Technique Rucinski, Slavek M.
Proceedings of the International Astronomical Union,
07/2011, Letnik:
7, Številka:
S282
Journal Article
Recenzirano
Odprti dostop
Essential assumptions and features of the Broadening Function (BF) technique are presented. A distinction between BF determination and the BF concept and utilization is made. The BF's can be ...determined in various ways. The approach based on linear deconvolution involving stellar templates, as used during the DDO program (1999 – 2008) is described, but the LSD technique would also give excellent results. The BF concept to prove and/or verify photometric light-curve solutions has so far been very limited to only a few W UMa-type binaries, with AW UMa giving particularly unexpected results.
Tycho-Gaia Astrometric Solution (TGAS) parallax data are used to determine absolute magnitudes MV for 318 W UMa-type (EW) contact binary stars. A very steep (slope −9), single-parameter ( ), linear ...calibration can be used to predict MV to about 0.1-0.3 mag over the whole range of accessible orbital period, days. A similar calibration for the most common systems with days predicts MV values to about 0.06-0.16 mag. For orbital period values both shorter and longer than the central range, the period dependence is respectively steeper and shallower, i.e., the binaries are fainter in MV than predicted by the whole-range linear law. The steepness of the relation for short-period systems implies important consequences for the detectability of the faintest binaries, defining the short-period cut-off of the period distribution. Although the scatter around the linear -fit is fairly large (0.2-0.4 mag), the current data do not support the inclusion of a color term in the calibration.
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