This is a program of observations of a remarkable class of celestial objects, the Soft X-ray Transient systems, consisting of a black hole or neutron star accreting matter from a Sun-like companion star. The accretion is episodic, with short intense outbursts of X-rays (the bulk of the emitted energy) alternating with long stretches of quiescent behavior. By combining observations of quiescence phases and of the outbursts, and by studying the optical and infrared radiation alongside the high energy radiation, one can create a more complete and detailed picture of these remarkable sources and the exotic physical effects that take place in them. Without such complementary ground-based optical/infrared observations, the data from NASA's fleet of high-energy observatories cannot be adequately interpreted.
Broader Impacts. This project is one of the key programs in the Small and Moderate Aperture Research Telescope System, and the Principal Investigator is the Principal Scientist of this consortium. The group provides well-instrumented 1m-class telescopes in the southern hemisphere at the Cerro Tololo Interamerican Observatory that are available to all US astronomers through proposals to the National Optical Astronomy Observatories. Data of the kind obtained forms an ideal basis for undergraduate research projects, and this program provides many opportunities for undergraduates to carryout front-line research. There is continuing work in creating web-based public outreach tools and on-line courses to inform the public of project results.
