engleski

Digging the Asiago plate archive for symbiotic stars

We present the results of digging the rich archive plate of the Asiago observatory for symbiotic stars. A first bunch of objects have been located and measured on 1237 plates: AS 323, Ap 3-1, CM Aql, V1413 Aql (=AS 338), V443 Her, V627 Cas (=AS 501), V919 Sgr, Hen 2-468, QW Sge, LT Del, V407 Cyg, K 3-9, V335 Vul, FG Ser and Draco C-1. The results are published in Munari et al. (2001, A\&A 370, 503 ; 2002 astro-ph/0202118). Their brightness has been estimated against the $UBV(IR)_{;C};$ photometric sequences calibrated by Henden and Munari (2000 A\&A 372, 145 ; 2001 A\&AS 143, 343). The program aims are twofold. First, to contribute the Asiago data to the community interested in reconstructing historical lightcurves of symbiotic stars. Second, to derive physical information and parameters like orbital periods, presence of eclipses, tidal distortions, etc. Historical data have allowed for the first time the determination of the orbital periods of Hen 2-468 (774 days), QW Sge (390.5 days), CM Aql (P=1058 days) and AS 323 (197.6 days) which was also discovered to be quite probably an eclipsing system with the shortest known orbital period among symbiotic stars. A significant improvement in the orbital period of LT Del (456.6 days) was obtained too. The lightcurves of the other program stars turned out to provide precious information on previously unknown outbursts, firmer mapping of pulsation cycles, secular trend of their cool components.

symbiotis stars; photometry

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