We present an analysis of the evolution of circumstellar dust and molecules in the environment of the very late thermal pulse object V4334 Sgr ( Sakurai ’ s Object ) over a \sim 20 -year period , drawing on ground- , airborne- and space-based infrared photometry and spectroscopy .
The dust emission , which started in 1997 , resembles a blackbody that cooled from \sim 1 , 200 K in 1998 August to \sim ∼ 180 K in 2016 July .
The dust mass , assuming amorphous carbon , was \sim 5 \times 10 ^ { -10 } M _ { \odot } in 1998 August , and we estimate that the total dust mass was \sim 2 \times 10 ^ { -5 } M _ { \odot } by \sim 2016 .
The appearance of a near infrared excess in 2008 suggests a new episode of ( or renewed ) mass loss began then .
We infer lower limits on the bolometric luminosity of the embedded star from that of the dust shell , which rose to \sim 16 , 000 L _ { \odot } before declining to \sim 3 , 000 L _ { \odot } .
There is evidence for weak 6–7 \mu m absorption , which we attribute to hydrogenated amorphous carbon formed in material ejected by Sakurai ’ s Object during a mass ejection phase that preceded the 1997 event .
We detect small hydrocarbon and other molecules in the spectra , and trace the column densities in hydrogen cyanide ( HCN ) and acetylene ( C _ { 2 } H _ { 2 } ) .
We use the former to determine the ^ { 12 } C/ ^ { 13 } C ratio to be 6.4 \pm 0.7 , 14 times smaller than the Solar System value .