Mon. Not. R. Astron. Soc., 448, 1789-1806 (2015/April-1)
A radial velocity survey for post-common-envelope Wolf-Rayet central stars of planetary nebulae: first results and discovery of the close binary nucleus of NGC 5189.
MANICK R., MISZALSKI B. and McBRIDE V.
Abstract (from CDS):
The formation of Wolf-Rayet central stars of planetary nebulae ([WR] CSPNe) whose spectroscopic appearance mimics massive WR stars remains poorly understood. Least understood is the nature and frequency of binary companions to [WR] CSPNe that may explain their H-deficiency. We have conducted a systematic radial velocity (RV) study of six [WR] CSPNe to search for post-common-envelope (post-CE) [WR] binaries. We used a cross-correlation method to construct the RV time series as successfully done for massive close binary WR stars. No significant RV variability was detected for the late-[WC] type nuclei of Hen 2-113, Hen 3-1333, PMR 2 and Hen 2-99. Significant, large-amplitude variability was found in the [WC4] nucleus of NGC 5315. In the [WO1] nucleus of NGC 5189, we discovered significant periodic variability that reveals a close binary with Porb = 4.04±0.1 d. We measured a semi-amplitude of 62.3±1.3 km/s that gives a companion mass of m2 ≥ 0.5 M☉ or m2 = 0.84 M☉ (assuming i = 45°). The most plausible companion type is a massive white dwarf (WD) as found in Fleming 1. The spectacular nebular morphology of NGC 5189 fits the pattern of recently discovered post-CE PNe extremely well with its dominant low-ionization structures (e.g. as in NGC 6326) and collimated outflows (e.g. as in Fleming 1). The long 4.04 d orbital period is either anomalous (e.g. NGC 2346) or it may indicate that there is a sizeable population of [WR] binaries with massive WD companions in relatively wide orbits, perhaps influenced by interactions with the strong [WR] wind.
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
stars: AGB and post-AGB - binaries: spectroscopic - stars: Wolf-Rayet - planetary nebulae: general - planetary nebulae: individual: NGC 5189
Misprints: PN G355.2-03.6 = PN G335.2-03.6, PHR 1757-2724 = PHR 1757-2824.
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