Sakurai's Object: characterizing the near-infrared CO ejecta between 2003 and 2007 |
| |
Authors: | H L Worters M T Rushton S P S Eyres T R Geballe A Evans |
| |
Institution: | Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE;South African Astronomical Observatory, Observatory, 7935, South Africa;Gemini Observatory, 670 N. A'ohoku Place, Hilo, HI 96720, USA;Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG |
| |
Abstract: | We present observations of Sakurai's Object obtained at 1–5 μm between 2003 and 2007. By fitting a radiative transfer model to an echelle spectrum of CO fundamental absorption features around 4.7 μm , we determine the excitation conditions in the line-forming region. We find 12C/13C = 3.5+2.0−1.5 , consistent with CO originating in ejecta processed by the very late thermal pulse, rather than in the pre-existing planetary nebula. We demonstrate the existence of 2.2 × 10−6≤ M CO≤ 2.7 × 10−6 M⊙ of CO ejecta outside the dust, forming a high-velocity wind of 500 ± 80 km s−1 . We find evidence for significant weakening of the CO band and cooling of the dust around the central star between 2003 and 2005. The gas and dust temperatures are implausibly high for stellar radiation to be the sole contributor. |
| |
Keywords: | stars: abundances stars: AGB and post-AGB circumstellar matter stars: individual: V4334 Sgr stars: individual: Sakurai's Object stars: winds outflows |
|
|