| Abstract
| - ABSTRACT. We present UKIRT UIST spectra of Sakurai's Object (= V4334 Sgr) showing CO fundamental-band absorption features around 4.7 μm. The line centres are at a heliocentric radial velocity of −170 ± 30 km s−1. The number and relative strengths of the lines indicate a CO gas temperature of 400 ± 100 K and a CO column density of 7+3−2× 1017 cm−2. The gas was moving away from the central star at an average speed of ∼290 ± 30 km s−1 in 2003 September. The lines appeared sometime between mid-1999 (well after the opaque dust shell formed) and mid-2000, and may have been somewhat more blueshifted initially than they are now. The observed CO velocity and temperature indicate the continued presence of a fast wind in the object, previously seen in the He i 1.083-μm line beginning just prior to massive dust formation, and more recently in atomic and ionized lines. The dust continuum is consistent with a temperature of 350 ± 30 K, indicating continued cooling of the shell. The similar CO temperature suggests that the bulk of the CO absorption occurs just outside the dust continuum surface.
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