Warm high-velocity CO in the wind of Sakurai's Object (= V4334 Sgr)

Abstract

Listen

Translate article

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.