The planetary nebula K 1-2 and its binary central star VW Pyx

Abstract

New data are presented of the post‐common‐envelope binary VW Pyx and its associated planetary nebula (PN), K 1‐2. The central star is found to be a single‐lined (and possibly double‐lined) spectroscopic binary and is a good candidate for a system in which the main‐sequence secondary star is more massive than the subdwarf primary star. The old PN has a high excitation level and a measured electron temperature, TO∼ 17 000 K for an assumed log ne= 2.7 cm−3. The so‐called ‘jets’ are found to be lower‐ionization regions with TN∼ 11 000 K and TO∼ 16 000 K with log ne∼ 2.5 cm−3 and with low, but fairly typical, PN abundances. We discuss possible histories for K 1‐2 and the jets. However, there are still many unknowns in the study of accretion and jet formation for such PN binary central stars.

Binary Central Stars of Planetary Nebulae Discovered Through Photometric Variability. I. What We Know and What We Would Like to Find Out

“…Kohoutek & Schnur (1982) determined the Zanstra (He ii) temperature of the star (79,000-91,000 K). Exter et al (2003b) reported that the central star of this post-CE binary is a single-lined or possibly a doublelined spectroscopic binary, where the primary star absorption lines can barely be resolved, while the emission line spectrum of the irradiated secondary dominates. The spectrum is very similar to that of V664 Cas (HFG 1).…”

Binary planetary nebulae nuclei towards the Galactic bulge

“…The central CCD was read out with 2 × 2 binning to give a 5.5 × 2.5 arcmin field-of-view sampled at 0.145 ′′ /pixel. Bond & Livio (1990), (d) Schwarz, Corradi & Melnick (1992), (e) Walsh & Walton (1996), (f) Heckathorn, Fesen & Gull (1982), (g) Pollacco & Bell (1997), (h) Hua, Dopita & Martinis (1998), (i) Corradi et al (1999), (j) Bond (2000), (k) De Marco (2009), (l) Corradi et al (2000), (m) Exter, Pollacco & Bell (2003), (n) Liebert et al (1995) Our primary focus in this work is on the new OGLE sample rather than previously well-studied known sample. Section 4 will present a selection of more detailed images of the OGLE sample than that provided in Fig.…”

“…Perhaps the most ambiguous case being the highly collimated 'jet-like' pairs often quoted as 'jets' (e.g. Exter et al 2003) even though their velocities not substantially different from their nebulae (Gonçalves 2004). We describe knots as unresolved or small LIS with an aspect ratio of unity, and filaments as knots with an aspect ratio larger than unity (Gonçalves et al 2001).…”

“…All previous studies of K 1-2 have focused solely on the multiple opposing pairs of low-ionisation filaments (Corradi et al 1999;Exter et al 2003), rather than the overall nebula structure. ner gap and elongation in the N-S direction closely mirrors the elliptical shape and cross-section of the gap in Model A.…”

On the possible triple central star system of PN SuWt 2: no ménage à trois at the heart of the Wedding Ring

“…The strongest remaining candidate is, without doubt, PN SuWt 2 (Schuster & West 1976), a ring nebula (see figure 1) where the bright star closest to the projected nebular centre has been shown to be a 4.9 day period binary consisting of two, almost identical, A-type main-sequence stars (Bond et al 2002;Exter et al 2003). Exter et al (2010) performed a detailed analysis of this double A-type system (NSV 19992 from hereon; Kazarovets et al 1998), showing both components to be A1V stars of mass ∼2.7M ⊙ , neither of which could be the source of photoionisation nor the nebular progenitor (the nebular abundances indicate a post-AGB progenitor; Smith et al 2007).…”