ER UMa ER Ursae Majoris stars or RZ Leo Minoris stars

- ER Ursae Majoris stars are dwarf nova subtypes that exhibit a standstill like phase similar to Z Camelopar-dalis stars. They exhibit short outbursts that resemble normal outbursts of SU Ursae Majoris stars in regards to their rapid decline rate, not recognized within the GCVS

ER UMa was originally discovered as an ultraviolet-excess object and confirmed to be a cataclysmic variable in 1986. Until very recently the object had been little studied. It was only in 1992 that the dwarf nova nature of this object was first noticed. Intensive visual observations have revealed that the object varies between 12T3 and 151'2 in V. The most peculiar photometric behavior of this object is the presence of a standstill-like phase following the initial decline of some outbursts.

The star stays in this phase for ten days or so at 0™5 to ln.'0 fainter than the outburst maximum. These characteristics closely resemble short standstills observed in Z Cam stars.

Another intriguing feature is the presence of short, but occasionally bright, outbursts with a maximum decline rate of 0™7 per day. These short outbursts resemble normal outbursts of SU UMa stars in the sense of its rapid decline rate, although no previously known SU UMa stars have been shown to exhibit the Z Cam-type characteristics at the same time.


A' fain' stars

Vs- Small omplitud

Q. Short periods

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