Extended Deep Minimum and Subsequent Brightening of RX And in 1996-1997

We discovered that RX And, one of prototypical Z Cam-type dwarf novae,underwent a deep, extended faint state in 1996-1997. Time-resolved photometryat the bottom of the fading revealed the presence of strong flickering, and theabsence of detectable orbital modulation. This finding indicates that themass-transfer remained even at the deepest minimum of the fading, contrary towhat was observed in a deep minimum of a VY Scl-type star, MV Lyr. RX Andsubsequently underwent a brightening (outburst) during its recovery stage. Thephotometric and spectroscopic characteristics of the brightening significantlydiffered from those of ordinary outbursts of RX And, and are considered toresemble an inside-out type outburst of a long-period dwarf nova. Anexamination of historical visual observations revealed the possible presence of\~10-yr periodicity, which is close to what has been proposed for MV Lyr. Thecommon observed features between RX And and VY Scl-type stars may suggest acommon underlying mechanism for producing temporary deep fadings. The departurefrom the disk instability model, as observed in VY Scl-type stars, was notapparent in the present fading of RX And. In conjunction with the recentlypublished Hubble Space Telescope observation during the same fading, we canconclude that the phenomenological difference from the VY Scl-type fading isunderstood as a smaller effect of irradiation on the accretion disk in RX And.Comment: 7 pages, 5 figures, accepted for publication in PAS