Symbiotic stars are interacting binary stars composed of an evolved
red giant and a hot companion star. Most symbiotics have orbital periods
of a few years; some systems orbit over several decades. In all systems,
the hot component - a main sequence star, a white dwarf, or a neutron
star - accretes material lost by the red giant. This accreted material
powers symbiotic activity, including occasional eruptions and jets.
Aside from writing the book on symbiotic stars (The Symbiotic Stars,
published by Cambridge University Press), I study the physical structure
and long-term evolution of these binary systems. I combine theoretical models
with multiwavelength spectroscopy to infer the physical properties of the
red giant, the hot component, and the disk surrounding the hot component.
Recently, I have worked with Jeno Sokoloski on the outbursts of Z And and RS Oph. In Z And, we showed that
a disk instability triggers thermonculear eruptions in the hot component. In RS Oph,
X-ray data from its recent outburst
allow us to infer that the hot component is a white dwarf with a mass
to the maximum allowed mass (Chandrasekhar limit).