SX Leonis Minoris is a
dwarf nova
A U Geminorum-type variable star, or dwarf nova (pl. novae) is one of several types of cataclysmic variable star, consisting of a close binary star system in which one of the components is a white dwarf that accretes matter from its companion. ...
of the
SU Ursae Majoris
SU Ursae Majoris, or SU UMa, is a close binary star in the northern circumpolar constellation of Ursa Major. It is a periodic cataclysmic variable that varies in magnitude from a peak of 10.8 down to a base of 14.96. The distance to th ...
type that was first discovered as a 16th magnitude blue star in 1957, before its identity was confirmed as a dwarf nova in 1994. The system consists of a white dwarf and a donor star which orbit around a common centre of gravity every 97 minutes. The white dwarf sucks matter from the other star via its
Roche lobe
In astronomy, the Roche lobe is the region around a star in a binary system within which orbiting material is gravitationally bound to that star. It is an approximately teardrop-shaped region bounded by a critical gravitational equipotential, ...
onto an
accretion disc which is heated to between 6000 and 10000 K and periodically erupts every 34 to 64 days, reaching magnitude 13.4 in these outbursts and remaining at magnitude 16.8 when quiet. These outbursts can be split into frequent eruptions and less frequent supereruptions. The former are smooth, while the latter exhibit short "superhumps" of heightened activity and last 2.6% longer.
SX Leonis Minoris has been calculated as lying 489 to 688 light years (150 to 211 parsecs) distant from the
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
via extrapolation of the, or more recently as 360 parsecs (1174 light years) via calculation using orbital period and absolute magnitude. The donor star has been calculated to have only 11% the mass of the white dwarf. It is thought to be a red dwarf of spectral type M5 to M7, but infrared observation or spectroscopy is obscured by the white dwarf's accretion disc.
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External links
{{DEFAULTSORT:SX Leonis Minoris
Leo Minor
Dwarf novae
Leonis Minoris, SX