Morphologies of Wolf–Rayet Planetary Nebulae Based on IFU Observations

Ashkbiz Danehkar

doi:10.3390/galaxies10020045

Abstract

Integral field unit (IFU) spectroscopy of planetary nebulae (PNe) provides a plethora of information about their morphologies and ionization structures. An IFU survey of a sample of PNe around hydrogen-deficient stars has been conducted with the Wide Field Spectrograph (WiFeS) on the ANU 2.3-m telescope. In this paper, we present the Hα kinematic observations of the PN M 2-42 with a weak emission-line star (wels), and the compact PNe Hen 3-1333 and Hen 2-113 around Wolf–Rayet ([WR]) stars from this WiFeS survey. We see that the ring and point-symmetric knots previously identified in the velocity [N ii] channels of M 2-42 are also surrounded by a thin exterior ionized Hα halo, whose polar expansion is apparently faster than the low-ionization knots. The velocity-resolved Hα channel maps of Hen 3-1333 and Hen 2-113 also suggest that the faint multipolar lobes may get to a projected outflow velocity of ∼100 ± 20 km s−1 far from the central stars. Our recent kinematic studies of the WiFeS/IFU survey of other PNe around [WR] and wels mostly hint at elliptical morphologies, while collimated outflows are present in many of them. As the WiFeS does not have adequate resolution for compact (≤6 arcsec) PNe, future high-resolution spatially-resolved observations are necessary to unveil full details of their morpho-kinematic structures.

Highlights

Introduction of WolfRayet Planetary NebulaeAsymptotic giant branch (AGB) stars with low to intermediate initial masses (1–8 M )expel hydrogen-rich envelopes, which are subsequently photo-ionized by UV radiation from post-AGB degenerate cores, resulting in so-called planetary nebulae (PNe)
We see that the ring and point-symmetric knots previously identified in the velocity [N II] channels of M 2-42 are surrounded by a thin exterior ionized Hα halo, whose polar expansion is apparently faster than the low-ionization knots
The gaseous structures of these expanding ionized H-rich envelopes seen in the optical band, thanks to photoionization, are modified by stellar winds from their remnant central stars as they move on their evolutionary path toward the white dwarf stage

Summary

Introduction of Wolf–Rayet Planetary Nebulae

Asymptotic giant branch (AGB) stars with low to intermediate initial masses (1–8 M ). The gaseous structures of these expanding ionized H-rich envelopes seen in the optical band, thanks to photoionization, are modified by stellar winds from their remnant central stars as they move on their evolutionary path toward the white dwarf stage Their strong collisionally excited line emissions reveal their morphological features to us across the Galaxy, making them powerful kinematic probes. The WiFeS offers a seeing of ∼ 200 and a velocity resolution of ∼21 km s−1 in the red channel at R ∼7000 This sample includes PNe around [WR] stars ranging from [WO 1] to [WC 6], and from [WC 9] to [WC 11] [37,40], as well as wels [41,42] (see Table 1 in Danehkar [29]), which could help us understand better the formation of aspherical morphologies and the mechanism scraping off hydrogen-rich layers in hydrogen-deficient degenerate cores.

M 2-42

Hen 3-1333 and Hen 2-113

Discussion

Conclusions