A Compilation of Systems That Are Both Novae and Dwarf Novae

Student: Ashley Dowd

Major: Physics, Astrophysics 

Mentor: Dr. Ashley Pagnotta

Department: Physics and Astronomy 

A Compilation of Systems That Are Both Novae and Dwarf Novae

In star systems that contain a white dwarf star (which is the remnant left over after a star like our Sun uses all its fuel) and a companion star, novae and dwarf novae are frequent occurrences. Both phenomena occur because hydrogen is being transferred from the companion star to the surface of the white dwarf. On its way to the white dwarf surface, the hydrogen gas travels through an accretion disk, a disk of hot matter orbiting the white dwarf. Instabilities in this disk can cause larger-than-usual clumps of hydrogen to be transferred onto the surface all at once, which causes small brightenings that we observe as dwarf nova outbursts. As the hydrogen gas slowly builds up on the surface of the white dwarf, the pressure becomes high enough to trigger runaway nuclear fusion, which we observe as a large brightening known as a nova eruption. We identified all of the systems known to have both novae and dwarf novae and compiled all of the available data on those systems, since such a compilation does not exist. We used that data to look for predicted correlations between the amount of time from nova eruption to dwarf nova outburst and physical characteristics of the systems, to better understand the evolution of such systems.