Deep Optical Images of the Ejecta Nebula around the Wolf–Rayet Star WR 8 (HD 62910)

Abstract

We report the results of deep H α and [O iii ] images of the bright WN6/WC4 Wolf–Rayet (WR) star WR 8 (HD 62910). These data show considerably more surrounding nebulosity than seen in prior imaging. The brighter portions of the nebula span $\simeq {6}^{{\prime} }$ in diameter and exhibit considerable fine-scale structure including numerous emission clumps and bright head-tail-like features, presumably due to the effects of the WR star’s stellar winds. Due to the overlap of a relatively bright band of unrelated foreground diffuse interstellar H α emission, WR 8’s nebula is best viewed via its [O iii ] emission. A faint ${9}^{{\prime} }\times 1{3}^{{\prime} }$ diffuse outer nebulosity is detected surrounding the nebula’s main ring of emission. Comparison of the nebula’s optical structure with that seen in Wide-field Infrared Survey Explorer 22 μ m data shows a similarly clumpy structure but within a better-defined emission shell of thermal continuum from dust. The infrared shell is coincident with the nebula’s southern [O iii ] emissions but is mainly seen in the fainter outer portions of the northern [O iii ] emission clumps. It is this greater radial distance of dust emission in the nebula’s northern areas that leads to a striking off-center position of the WR star from the IR shell.

Keywords

• Wolf-Rayet stars
• Emission nebulae