The outer wind of γ Velorum
Abstract
Fine-structure mid-infrared emission lines with critical densities in the regime 104 ≤ ncrit ≤ 106 cm-3 can be employed to probe the outflow from Wolf-Rayet (WR) stars at radii of ∼1015 cm. Narrow-band mid-infrared imaging and spectroscopy of the nearest WR star to the Sun, γ Velorum is analysed for spatially resolved forbidden line emission in the WR outer wind. The [S IV] 10.52-μm and [Ne II] 12.81-μm emission regions are found to be spatially extended, compared to unresolved continuum and He and C recombination line emission. The [S IV] and [Ne II] emission line distributions have a high degree of azimuthal symmetry, indicating a spherically symmetric outflow. A model wind with a modest degree of clumping (clumping factor f ∼ 10) provides a better match to the observations than an unclumped model. The overall line intensity distributions are consistent with a freely expanding, spherically symmetric 1/r2 outflow with constant ionization fraction and modestly clumped density structure.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2012
- DOI:
- 10.1111/j.1365-2966.2012.22005.x
- arXiv:
- arXiv:1208.6016
- Bibcode:
- 2012MNRAS.427..581R
- Keywords:
-
- circumstellar matter;
- stars: abundances;
- stars: individual: γ Velorum;
- stars: winds;
- outflows;
- stars: Wolf-Rayet;
- infrared: stars;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 8 pages including 3 Tables and 7 Figures. MNRAS in press