Binary planetary nebulae nuclei towards the Galactic bulge

Abstract

Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). A binary companion is increasingly gaining support as a dominant shaping mechanism, however morphological studies of the few PNe that we know for certain were shaped by binary evolution are scarce or biased. Newly discovered binary central stars (CSPN) from the OGLE-III photometric variability survey have significantly increased the sample of post common-envelope (CE) nebulae available for morphological analysis. We present Gemini South narrow-band images for most of the new sample to complement existing data in a qualitative morphological study of 30 post-CE nebulae. Nearly 30% of nebulae have canonical bipolar morphologies, however this rises to 60% once inclination effects are incorporated with the aid of geometric models. This is the strongest observational evidence yet linking CE evolution to bipolar morphologies. A higher than average proportion of the sample shows low-ionisation knots, filaments or jets suggestive of a binary origin. These features are also common around emission-line nuclei which may be explained by speculative binary formation scenarios for H-deficient CSPN.

Discovery of close binary central stars in the planetary nebulae NGC 6326 and NGC 6778

“…They add to the mounting observational evidence of jets associated with post-CE PNe (Mitchell et al 2007;Miszalski et al 2009b;Corradi et al 2011;Miszalski et al 2011b). In NGC 6326 we have noted for the first time a thin pair of jets at PA = 145 • that complements what seems to be jets beyond the "whiskers" at PA = 50-80 • .…”

“…Section 2 presents proof of close binary CSPN in NGC 6326 (PN G338.1−08.3) and NGC 6778 (PN G034.5−06.7), both selected for study solely because of their rich attribution of low-ionisation structures (Schwarz et al 1992;Corradi et al 1996;Miranda et al 2010). These discoveries were made during the course of ongoing work by our team (Miszalski et al 2009a(Miszalski et al , 2011aCorradi et al 2011;Santander-García et al 2011) that aims to further strengthen the trends specific to post-CE nebulae first identified by Miszalski et al (2009b). Section 3 discusses the morphological features of both nebulae and Sect.…”

“…Sahai 2000;Sahai et al 2011). The first steps towards proving the connection between jets and post-CE CSPN have been made (Mitchell et al 2007;Corradi et al 2011;Miszalski et al 2011b), and further post-CE specific trends have been identified (Miszalski et al 2009b), but many other challenges remain (De Marco 2009). Further progress depends critically on developing new survey techniques for binary CSPN to build a statistically significant sample of a few hundred post-CE nebulae.…”

The post-common envelope central stars of the planetary nebulae Henize 2-155 and Henize 2-161

“…2), as well as several other post-CE PNe (e.g. Sab 41, Miszalski et al 2009b;and Fg 1, Boffin et al 2012b). Once again, the central binary of the Necklace shows extremely strong variability and a relatively short period (1.16 day, Corradi et al 2011), but is of special interest due to the chemical peculiarity of the companion star in the system.…”

Are planetary nebulae derived from multiple evolutionary scenarios?

“…Post-CE PNe appear to have quite distinct observational properties (Bond & Livio 1990;Frew & Parker 2007;Miszalski et al 2009). Moreover, some post-CE PNe may contain double degenerate cores (e.g.…”