WR 72: a born-again planetary nebula with hydrogen-poor knots

Abstract

We report the discovery of a handful of optical hydrogen-poor knots in the central part of an extended infrared nebula centred on the [WO1] star WR 72, obtained by spectroscopic and imaging observations with the Southern African Large Telescope (SALT). Wide-field Infrared Survey Explorer (WISE) images of the nebula show that it is composed of an extended almost circular halo (of $\approx 6$ arcmin or $\approx 2.4$ pc in diameter) and an elongated and apparently bipolar inner shell (of a factor of six smaller size), within which the knots are concentrated. Our findings indicate that WR 72 is a new member of the rare group of hydrogen-poor planetary nebulae, which may be explained through a very late thermal pulse of a post-AGB star, or by a merger of two white dwarfs.

7 pages, 5 figures, accepted for publication in MNRAS

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Cited by in corpus (8)

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• Catching a grown-up starfish planetary nebula II. Plasma analysis and central star properties of PC 22
• Non-thermal radio emission in Sakurai's Object
• First images of the molecular gas around a born-again star revealed by ALMA
• Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics
• A primer on the formation and evolution of hydrogen deficient Central Stars of Planetary Nebulæ and Related Objects