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| 0072 | New Elements for 54 Eclipsing Binaries
3617 kB | Sebastián A. Otero | | 2007-10-14 | | | This research presents new elements for 54 eclipsing binaries found using data from the ASAS-3, Hipparcos and NSVS databases. Some of the systems studied are new and others are confirmed or had wrong elements in the literature. The discovery of apsidal motion in TZ Pyx is presented and an identification problem with CPD-41 7746 in NGC 6231 is addressed. Conspicuous BE-variability superposed to eclipsing variations is discovered in HD 61407. Simbad object(s): HD 326334, HD 326319, HD 152291, V3903 Sgr, AF Gru, V1905 Cyg, V1901 Cyg, HD 199587, BP Del, HD 188942, V2094 Cyg, BN Dra, NSV 11763, HD 174344, NSV 10625, CCDM J18061-2412AB, V1090 Sco, CPD-41 7746, V712 Her, HD 143156, ... | comments: 2 |
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Sebastián A. Otero wrote 2007-10-20:
ERRATUM on TZ Pyx apsidal motion
The announced apsidal motion for TZ Pyx is most likely spurious.
Further analysis showed that the eclipse durations for Min I and Min II are the same while Min II falls at phase 0.50. This is not consistent with an eccentric orbit and thus with apsidal motion.
Examination of old times of minimum published in IBVS 225 (Strohmeier, 1967) that were not used for the analysis because the star was classified as EW with a wrong period of 0.69 days in the original reference, supports the fact that there are not two different periods for Min I and Min II, the true and unique period being 2.318555 d, which is within the error limits of the period given for Min II in OEJV 72. Using this period still leaves a consistent shift (0.007 phase units) in the Hipparcos observations but the rest of the evidence and the physical nature of the system points to the HIP shift being just an unlucky coincidence caused by photometry errors due to this star being very much fainter (11th mag.) than the average Hipparcos star and the true photometric errors probably larger than stated in the catalogue. If there is a slight chance that this shift is caused by an actual apsidal motion in a very slightly eccentric orbit, this possibility is only marginal and shouldn't be considered as significant in the light of the new evidence.
Complete light curves would help to definitely solve the question.
The use of Hipparcos data for stars this faint should be made with special care to avoid jumping to conclussions like in this case.
Reference:
Strohmeier, W., 1967, IBVS, No. 225 (1967IBVS..225....1S)
uxzvgaihc fhqtimeb wrote 2008-07-10:
hlsag ejal vomstdnfe tesxmc kztadncru otlwvdha zcopsgtav
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