2020ApJ...904...34H

Observations of the ejecta from the final flash (FF) of helium shell burning in Sakurai's Object (V4334 Sgr) are presented for 2015-2019, a period ∼20-24 yr after discovery. Adaptive optics images at K_s trace the expanding debris. While most of the ejecta mass is in ∼200 K dust, a small fraction, ∼0.4%, of the dust mass is at ∼760 K. The 760 K continuum dominates the near-IR images. Spatial-spectral images in He I 10830 Å show an ∼1.''6 diameter bipolar planetary nebula at position angle 21° ± 5° with the SW moving toward us and the NE moving away. Seen in integrated light, the nebula is nearly circular. Near-IR continuum images show ejecta moving radially away from a bright central point source. High-resolution mid-IR spectra reveal molecular hydrocarbon lines with an expansion velocity of 270 ± 5 km s^–1 seen in absorption against the dust continuum. The hydrocarbons originate in material produced in the FF. The bipolar nebula and debris clouds are discussed in the context of a highly inclined disk model. The proper motion has been measured placing V4334 Sgr in the thick disk population. There is no evidence that a hot white dwarf Wolf-Rayet ([WR]) wind has emerged; no [WR] spectral features were detected. The possibility of a binary companion involved in the evolution is discussed.