Volume 562, February 2014
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||11 February 2014|
The post-common-envelope, binary central star of the planetary nebula Hen 2-11 ⋆
1 European Southern Observatory, Alonso de Córdova 3107, 19001 Casilla, Santiago, Chile
e-mail: firstname.lastname@example.org; email@example.com
2 Universidad de Atacama, Copayapu 485, Copiapó, Chile
3 South African Astronomical Observatory, PO Box 9, Observatory, 7935 Cape Town, South Africa
4 Southern African Large Telescope Foundation, PO Box 9, Observatory, 7935 Cape Town, South Africa
5 Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
6 Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
7 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
Received: 4 October 2013
Accepted: 2 January 2014
We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology – traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type i nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity.
Key words: binaries: close / binaries: eclipsing / circumstellar matter / ISM: abundances / stars: AGB and post-AGB / planetary nebulae: individual: Hen 2-11
Extracted 1D spectra, reduced 2D spectra, and table of photometry are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/562/A89
© ESO, 2014
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