# # Program information file # PROGRAM_ID 2021B076 PROGRAM_TITLE The Disk Eclipse of R Aqr PROGRAM_INV1 Kenneth Hinkle PROGRAM_INV2 Sean Brittain PROGRAM_INV3 Francis Fekel PROGRAM_INV4 Thomas Lebzelter PROGRAM_INV5 Adwin Boogert PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG The AGB/white dwarf [WD] binary system R Aqr contains a dusty flow from the AGB star to an accretion disk around the WD. R Aqr is nearby, bright, and extensively studied. The system is a 'disk-eclipse' binary where the accretion disk/mass flow eclipses the AGB star every 44 years. An eclipse is currently underway. We observed the eclipse using high-resolution M and K iSHELL spectra in September 2020. We propose to continue the observations. Spectra of the CO fundamental and first overtone probe the gas in the disk and mass flow as it passes in front of the AGB star. Velocities, temperatures, and column densities can be measured in streams crossing in front of the stellar photosphere, allowing resolution of few AU. First spectra of the leading edge show a 1200 K region of the Keplerian disk facing the AGB star. CO is seen in emission from the hot edge and in absorption streaming inward to the cooler disk. A set of spectra spanning the eclipse will map flows showing how the gas and dust is routed through the circumstellar region and onto the WD. This will provide the first detailed observations to compare with models of the mass transfer and accretion disk. PROGRAM_ABSTRACT_END