In-the-gap SU UMa-type dwarf nova, Var73 Dra with a supercycle of about 60 days

¹ Hida Observatory, Kyoto University, Kamitakara, Gifu 506-1314, Japan
² Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan
³ Cosmic Radiation Laboratory, Institute of Physical and Chemical Research (RIKEN), 2-1, Wako, Saitama 351-0198, Japan
⁴ DeKalb Observatory, 2507 County Road 60, Auburn, Auburn, Indiana 46706, USA
⁵ Department of Biosphere-Geosphere Systems, Faculty of Informatics, Okayama University of Science, 1-1 Ridaicho, Okayama 700-0005, Japan
⁶ Center for Backyard Astrophysics (Belgium), Walhostraat 1A, 3401 Landen, Belgium
⁷ Crimean Astrophysical Observatory, Nauchny, 98409 Crimea, Ukraine
⁸ Isac Newton Institute of Chile, Crimean Branch, Ukraine
⁹ Sternberg Astronomical Institute, 119899 Moscow, Russia
¹⁰ Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnij Arkhyz, Karachaevo-Cherkesia, Russia
¹¹ King's University College, Department of Physics, 9125 50th Street, Edmonton, AB T5H 2M1, Canada
¹² Center for Backyard Astrophysics (Concord), 1730 Helix Court, Concord, CA 94518, USA
¹³ Physics Department, University of Rome “Tor Vergata” Via della Ricerca Scientifica, 1 00133 Rome, Italy
¹⁴ Campo Catino Astronomical Observatory 03025 Guarcino, Italy

Corresponding author: D. Nogami, nogami@kwasan.kyoto-u.ac.jp

Received: 25 February 2003
Accepted: 1 April 2003

Abstract

An intensive photometric-observation campaign of the recently discovered SU UMa-type dwarf nova, Var73 Dra was conducted from 2002 August to 2003 February. We caught three superoutbursts in 2002 October, December and 2003 February. The recurrence cycle of the superoutburst (supercycle) is indicated to be ~60 d, the shortest among the values known so far in SU UMa stars and close to those of ER UMa stars. The superhump periods measured during the first two superoutbursts were 0.104885(93) d, and 0.10623(16) d, respectively. A 0.10424(3)-d periodicity was detected in quiescence. The change rate of the superhump period during the second superoutburst was , which is an order of magnitude larger than the largest value ever known. Outburst activity has changed from a phase of frequent normal outbursts and infrequent superoutbursts in 2001 to a phase of infrequent normal outbursts and frequent superoutbursts in 2002. Our observations are negative to an idea that this star is an related object to ER UMa stars in terms of the duty cycle of the superoutburst and the recurrence cycle of the normal outburst. However, to trace the superhump evolution throughout a superoutburst, and from quiescence more effectively, may give a fruitful result on this matter.