The binary fraction of planetary nebula central stars – II. A larger sample and improved technique for the infrared excess search
| Autor: | Dimitri Douchin, David J. Frew, Jean-Claude Passy, Michael T. Fitzgerald, George H. Jacoby, Maxwell Moe, D. Harmer, Orsola De Marco, G. Jasniewicz, Todd C. Hillwig |
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| Rok vydání: | 2015 |
| Předmět: |
Physics
Infrared excess education.field_of_study 010308 nuclear & particles physics Population Brown dwarf Astronomy Binary number White dwarf Astronomy and Astrophysics Astrophysics 01 natural sciences Planetary nebula Radial velocity Stars Space and Planetary Science 0103 physical sciences education 010303 astronomy & astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 448:3132-3155 |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | There is no conclusive explanation of why ∼80 per cent of planetary nebulae (PNe) are non-spherical. In the Binary Hypothesis, a binary interaction is a preferred channel to form a non-spherical PN. A fundamental step to corroborate or disprove the Binary Hypothesis is to estimate the binary fraction of central stars of PNe (CSPNe) and compare it with a prediction based on the binary fraction of the progenitor, main-sequence population. In this paper, the second in a series, we search for spatially unresolved I- and J-band flux excess in an extended sample of 34 CSPN by a refined measurement technique with a better quantification of the uncertainties. The detection rate of I- (J-)band flux excess is 32 ± 16 per cent (50 ± 24 per cent). This result is very close to what was obtained in Paper I with a smaller sample. We account conservatively for unobserved cool companions down to brown dwarf luminosities, increasing these fractions to 40 ± 20 per cent (62 ± 30 per cent). This step is very sensitive to the adopted brightness limit of our survey. Accounting for visual companions increases the binary fraction to 46 ± 23 per cent (71 ± 34 per cent). These figures are lower than in Paper I. The error bars are better quantified, but still unacceptably large. Taken at face value, the current CSPN binary fraction is in line with the main-sequence progenitor population binary fraction. However, including white dwarfs companions could increase this fraction by as much as 13 (21) per cent points. |
| Databáze: | OpenAIRE |
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