# # Program information file # PROGRAM_ID 2022B032 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 an accretion disk/mass flow eclipses the AGB star every 44 years. An eclipse is now underway, currently about two years past mid-eclipse, with an eclipse taking between four and eight years. The eclipse occurs near periastron. At periastron the Roche lobe becomes smaller than the disk and fuels the peculiar aspects of this system. High-resolution infrared spectroscopy of the M and K windows with iSHELL is proposed to supplement archival observations. By measuring CO fundamental and first overtone lines, the velocities, temperatures, and column densities of gas in the disk and mass flow will be measured as they cross in front of the stellar photosphere, allowing resolution of few AU. Models of existing observations show emission from the disrupted disk edge and an accretion bright spot. CO is also observed streaming away from the hot disk edge. This proposal will obtain observations near egress. Of particular interest is the mass flow from the mira to the WD. PROGRAM_ABSTRACT_END