Detection methods of binary stars with low- and intermediate-mass components

Jorissen, A.; Frankowski, A.

doi:10.1063/1.2999998

Cited by 8 publications

(6 citation statements)

References 146 publications

(240 reference statements)

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“…As a result, any companion later than ∼F0 V would not be detected. The tentative absence of variability ( §4.1) suggests the star does not have an irradiated companion (De Marco, Hillwig & Smith 2008;Miszalski et al 2009;Hajduk, Zilstra & Gesicki 2010), so time-series spectroscopic analysis is probably the best way to determine if Abell 48 is a binary (Jorissen & Frankowski 2008). However, at orbital periods greater than a year or two, the expected velocity shifts of the emission lines would be likely too small to be detected against the stochastic variations of the stellar wind.…”

Section: Stellar Spectral Energy Distributionmentioning

confidence: 99%

The planetary nebula Abell 48 and its [WN] nucleus

Frew¹,

Bojičić²,

Parker³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We have conducted a detailed multi-wavelength study of the peculiar nebula Abell 48 and its central star. We classify the nucleus as a helium-rich, hydrogen-deficient star of type [WN4-5]. The evidence for either a massive WN or a low-mass [WN] interpretation is critically examined, and we firmly conclude that Abell 48 is a planetary nebula (PN) around an evolved low-mass star, rather than a Population I ejecta nebula. Importantly, the surrounding nebula has a morphology typical of PNe, and is not enriched in nitrogen, and thus not the 'peeled atmosphere' of a massive star. We estimate a distance of 1.6 kpc and a reddening, E(B − V ) = 1.90 mag, the latter value clearly showing the nebula lies on the near side of the Galactic bar, and cannot be a massive WN star. The ionized mass (∼0.3 M ⊙ ) and electron density (700 cm −3 ) are typical of middle-aged PNe. The observed stellar spectrum was compared to a grid of models from the Potsdam Wolf-Rayet (PoWR) grid. The best fit temperature is 71 kK, and the atmospheric composition is dominated by helium with an upper limit on the hydrogen abundance of 10 per cent. Our results are in very good agreement with the recent study of Todt et al., who determined a hydrogen fraction of 10 per cent and an unusually large nitrogen fraction of ∼5 per cent. This fraction is higher than any other low-mass H-deficient star, and is not readily explained by current post-AGB models. We give a discussion of the implications of this discovery for the late-stage evolution of intermediate-mass stars. There is now tentative evidence for two distinct helium-dominated post-AGB lineages, separate to the helium and carbon dominated surface compositions produced by a late thermal pulse. Further theoretical work is needed to explain these recent discoveries.

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Section: Stellar Spectral Energy Distributionmentioning

confidence: 99%

The planetary nebula Abell 48 and its [WN] nucleus

Frew¹,

Bojičić²,

Parker³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…Companions to AGB stars are, however, extremely difficult to detect (Jorissen & Frankowski 2008) and it is probable that hidden binaries are included in our sample.…”

Section: Shaping Mechanismsmentioning

confidence: 99%

“…5,6 are available in electronic form at http://www.aanda.org companions are expected to influence the geometry, but information on the presence of companions is problematic. Apart from symbiotic systems, only a few dozen AGB binaries are known (Jorissen 2008), even though they are expected to be common. The reason so few are detected is because of the luminosity and variability of the AGB stars, and the opacity of their circumstellar envelopes.…”

Section: Introductionmentioning

confidence: 99%

Deep optical imaging of asymptotic giant branch circumstellar envelopes

Mauron

Huggins

Cheung

2013

A&A

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We report results of a program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered Galactic light. The goal is to characterize the shapes of the envelopes to probe the mass-loss geometry and the presence of hidden binary companions. The observations consist of deep optical imaging of 22 AGB stars with high mass loss rates: 16 with the ESO 3.6 m NTT telescope, and the remainder with other telescopes. The circumstellar envelopes are detected in 15 objects, with mass loss rates > ∼ 2 × 10 −6 M yr −1 . The surface brightness of the envelopes shows a strong decrease with Galactic radius, which indicates a steep radial gradient in the interstellar radiation field. The envelopes range from circular to elliptical in shape, and we characterize them by the ellipticity (E = major/minor axis) of iso-intensity contours. We find that ∼50% of the envelopes are close to circular with E < ∼ 1.1, and others are more elliptical with ∼20% with E > ∼ 1.2. We interpret the shapes in terms of populations of single stars and binaries whose envelopes are flattened by a companion. The distribution of E is qualitatively consistent with expectations based on population synthesis models of binary AGB stars. We also find that ∼50% of the sample exhibit small-scale, elongated features in the central regions. We interpret these as the escape of light from the central star through polar holes, which are also likely produced by companions. Our observations of envelope flattening and polar holes point to a hidden population of binary companions within the circumstellar envelopes of AGB stars. These companions are expected to play an important role in the transition to post-AGB stars and the formation of planetary nebulae.

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“…Our understanding of the intrinsic shaping mechanism of AGB envelopes is not well developed, but the expectation is that envelope shapes are different for single stars and binaries. Companions to AGB stars are, however, extremely difficult to detect (Jorissen & Frankowski 2008) and it is probable that hidden binaries are included in our sample.…”

Section: Shaping Mechanismsmentioning

confidence: 99%

“…Binary companions are expected to influence the geometry, Send offprint requests to: N. Mauron ⋆ Based on observations made at the European Southern Observatory, Chile (programs 078.D-0102, 082.D-0338 and 0.84.D-0302) and on de-archived data obtained with the ESO Very Large Telescope and with the NASA/ESA Hubble Space Telescope but information on the presence of companions is problematic. Apart from symbiotic systems, only a few dozen AGB binaries are known (Jorissen 2008), even though they are expected to be common. The reason so few are detected is because of the luminosity and variability of the AGB stars, and the opacity of their circumstellar envelopes.…”

Section: Introductionmentioning

confidence: 99%

Deep optical imaging of AGB circumstellar envelopes

Mauron,

Huggins,

Cheung

2013

Preprint

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We report results of a program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered Galactic light. The goal is to characterize the shapes of the envelopes to probe the mass-loss geometry and the presence of hidden binary companions. The observations consist of deep optical imaging of 22 AGB stars with high mass loss rates: 16 with the ESO 3.6 m NTT telescope, and the remainder with other telescopes. The circumstellar envelopes are detected in 15 objects, with mass loss rates > ∼ 2 × 10 −6 M⊙ yr −1 . The surface brightness of the envelopes shows a strong decrease with Galactic radius, which indicates a steep radial gradient in the interstellar radiation field. The envelopes range from circular to elliptical in shape, and we characterize them by the ellipticity (E = major/minor axis) of iso-intensity contours. We find that ∼50% of the envelopes are close to circular with E < ∼ 1.1, and others are more elliptical with ∼20% with E > ∼ 1.2. We interpret the shapes in terms of populations of single stars and binaries whose envelopes are flattened by a companion. The distribution of E is qualitatively consistent with expectations based on population synthesis models of binary AGB stars. We also find that ∼50% of the sample exhibit small-scale, elongated features in the central regions. We interpret these as the escape of light from the central star through polar holes, which are also likely produced by companions. Our observations of envelope flattening and polar holes point to a hidden population of binary companions within the circumstellar envelopes of AGB stars. These companions are expected to play an important role in the transition to post-AGB stars and the formation of planetary nebulae.

show abstract

Detection methods of binary stars with low- and intermediate-mass components

Cited by 8 publications

References 146 publications

The planetary nebula Abell 48 and its [WN] nucleus

The planetary nebula Abell 48 and its [WN] nucleus

Deep optical imaging of asymptotic giant branch circumstellar envelopes

Deep optical imaging of AGB circumstellar envelopes

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