Friday, July 5, 2013

1307.1238 (P. Mroz et al.)

Dwarf Novae in the OGLE Data. II. Forty New Dwarf Novae in the OGLE-III Galactic Disk Fields    [PDF]

P. Mroz, P. Pietrukowicz, R. Poleski, A. Udalski, I. Soszynski, M. K. Szymanski, M. Kubiak, G. Pietrzynski, L. Wyrzykowski, K. Ulaczyk, S. Kozlowski, J. Skowron
We report the discovery of forty erupting cataclysmic variable stars in the OGLE-III Galactic disk fields. Among them seventeen objects are of U Gem type, four of Z Cam type. Nineteen of the stars show outbursts and superoutbursts typical for SU UMa-type dwarf novae. In the case of five stars we were able to estimate their supercycle lengths. The obtained lengths are in the range 20-90 d, generally between the typical SU UMa-type variables and a few objects classified as the ER UMa-type variables. Since there is no significant difference between the two types but a higher mass-transfer rate resulting in more frequent outbursts and superoutbursts in the ER UMa-type stars, we propose to discard this type as a separate class of variables. We note that in one of the SU UMa-type stars, OGLE-GD-DN-039, we found a negative supercycle period change, in contrast to other active systems of this type. Two of the new OGLE objects showed long-duration WZ Sge-like superoutbursts followed by a sequence of echo outbursts. All stars reported in this paper are part of the OGLE-III Catalog of Variable Stars.
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