Symbiotic Stars as Laboratories for the Study of Accretion and Jets A Call for Optical Moni.pdfVIP

Sokoloski, JAAVSO Volume 31, 2003 89 Symbiotic Stars as Laboratories for the Study of Accretion and Jets: A Call for Optical Monitoring J. L. Sokoloski Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 Invited review paper, received June 20, 2003 Abstract Symbiotic binary stars typically consist of a white dwarf (WD) that accretes material from the wind of a companion red giant. Orbital periods for these binaries are on the order of years, and their relatively small optical outbursts tend to occur every few years to decades. In some symbiotics, material that is transferred from the red giant to the WD forms a disk around the WD. Thus, symbiotic stars are a bit like overgrown cataclysmic variables (CVs), but with less violent eruptions. Symbiotic stars are not as well understood as CVs, in part because their longer variability time scales mean that observations over many years are required to cover different outburst states and orbital phases. The recent discovery of collimated outflows (“jets”) from a number of symbiotics provides a new motivation for such long-term study of these objects. Astrophysical jets are observed in almost every type of accretion-powered system, and symbiotic stars may help us understand these structures. In symbiotics, most jets appear to be associated with optical eruptions. Optical monitoring by amateurs can identify systems in outburst, and also help to build a comprehensive database of outburst and quiescent symbiotic light curves. Together with radio through X-ray observations that will be performed when new outbursts are found, long-term optical light curves will improve understanding of symbiotic outbursts, jet production, and the connection between outbursts, jets, and accretion disks in symbiotic stars. 1. Introduction: What are symbiotic stars? Symbiotic stars are interacting binar