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J/A+A/489/321       Period study of TW Draconis                   (Zejda+, 2008)

Period study of TW Draconis. Zejda M., Mikulasek Z., Wolf M. <Astron. Astrophys. 489, 321 (2008)> =2008A&A...489..321Z (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Photometry Keywords: stars: binaries: eclipsing - stars: individual: TW Dra - stars: fundamental parameters Abstract: We present a study of time series data for the Algol-type eclipsing binaries TW Draconis obtained over the past 150 years to detect changes in minima timings. There is significant evidence for miscellaneous interacting physical processes in the system, which manifest themselves as for example period and light curve changes. Using 561 available minima timings, we compile an extended O-C diagram analysis. A detailed description of period changes allows us to construct the true phased light curve at any moment. The timing residuals (according to the linear ephemeris) display two stages of differing behaviour in 1858-2007. The first part ends around 1942. It is characterized by more or less smooth linear/parabolic course of timing residuals. In 1858-1905, the period was almost constant P=2.806513(9)d, but, in 1905-1942, the period increased due to mass exchange between components. Since 1942, the system has been showing alternating and shortening period changes with the length of a cycle of about two decades, modulated by short-term periodic variations. The latter small variations with the period 6.5-years are caused by the light-time effect due to the presence of a third low-mass body in the system. Major oscillations can be explained as consequences of quadrupole moment variation in the system. Description: The main table contains timings of minima of TW Draconis spanning past 150 years (1858-2008). Objects: --------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------- 15 33 51.1 +63 54 26 TW Draconis = V* TW Dra --------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 94 572 Timings of minima for TW Draconis
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 13 F13.5 --- HJD Heliocentric Julian Date of Minimum 15- 16 A2 --- N [: ] Designation on the accuracy of observations 18 A1 --- Min [ps] Type of minimum (p-primary, s - secondary) 21- 29 A9 --- Type Type of observations (1) 31- 51 A21 --- Observer Name of observer(s) 53- 92 A40 --- Source Source of information Reference 94 I1 --- Note [1/2]? Note (2)
Note (1): Type of observations ad follows: plate = dimming on photographic plates vis = visual observations pg = photographic observations pe = photoelectric measurements (used filters) CCD = CCD measurements (used filters) Note (2): Note as follows: 1 = new timing based on original photographic observation 2 = mean (in regard of color) timing of minimum
Acknowledgements: Miloslav Zejda, zejda(at)
(End) M. Zejda [DTPA MU Brno, Czech Republic], P. Vannier [CDS] 18-Jul-2008
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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