DQ Herculis
Encyclopedia
DQ Herculis (or Nova Herculis 1934) was a slow, bright nova
Nova
A nova is a cataclysmic nuclear explosion in a star caused by the accretion of hydrogen on to the surface of a white dwarf star, which ignites and starts nuclear fusion in a runaway manner...

 occurring in Hercules
Hercules (constellation)
Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles. Hercules was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations today...

 in December 1934. It reached magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 1.5.

DQ Herculis is the prototype for a category of cataclysmic variable stars called intermediate polar
Intermediate polar
An Intermediate Polar is a type of cataclysmic variable binary star system. In most cataclysmic variables, matter from a main-sequence companion star is gravitationally stripped by a white dwarf star in the form of an accretion disk. In intermediate polar systems, the accretion disk is disrupted...

s. The system shows orbital period variation, likely due to the presence of a third body.

Substellar companion

Dai & Qian (2009) invoke the presence of a third object to explain orbital period variations observed in the dwarf nova
Dwarf nova
A U Geminorum-type variable star, or dwarf nova is a type of cataclysmic variable starhttp://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/vartype.txt consisting of a close binary star system in which one of the components is a white dwarf, which accretes matter from its companion...

. If the third body is confirmed, it would likely turn out a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

 companion.
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