AAVSO: American Association of Variable Star Observers

Search for Dwarf Novae in DASCH Scans Near M44 (Abstract)

Volume 36 number 2 (2008)

Sumin Tang
Silas Laycock
Jonathan Grindlay


(Abstract only) Dwarf novae (DNe) are a subclass of Cataclysmic Variables (CVs) with outbursts powered by a disk instability leading to a sudden increase in the accretion rate. The Digital Access to a Sky Century at Harvard (DASCH) Collaboration is preparing to digitize over 500,000 Harvard plates from the 1880s to the 1980s with limiting magnitudes ranging from B = 14–19. As a demonstration project, we have scanned more than 500 plates in the fields centered on the galactic open cluster M44. There are twenty-one CVs in the fields within ten degrees of M44 covered by the scans Here we present the preliminary results of DN outbursts of the known CVs to derive long-term DN outburst duty cycles. In addition, a one hundred year light curve for a XMM-Newton source is also presented to demonstrate DASCH capabilities.