A mid-infrared imaging catalogue of post-asymptotic giant branch stars★

Lagadec, E.; Verhoelst, Tijl; Mékarnia, D.; Suárez, Olga; Zijlstra, A. A.; Bendjoya, Philippe; Szczerba, R.; Chesneau, O.; Winckel, H. Van; Barlow, M. J.; Matsuura, M.; Bowey, J. E.; Lorenz-Martins, S.; Gledhill, Tim

doi:10.1111/j.1365-2966.2011.18557.x

Cited by 101 publications

(114 citation statements)

References 95 publications

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“…The discovery of mass transfer and, possibly, accretiondriven jets in post-AGB binaries opens a new avenue to exploring some of the long-standing puzzles of these objects, such as a variable mass-loss rate, a long lifetime of the circumbinary disks, a lack of extended dusty nebulae (Siódmiak et al 2008;Lagadec et al 2011), and the bipolar structure of the gaseous outflows (Bujarrabal et al 2007). By uncovering more systems such as this in the course of our spectroscopic survey, aided by complimentary observations, we hope to pin-point the exact geometrical structures responsible for the various non-photospheric features.…”

Section: Discussionmentioning

confidence: 99%

Time-resolved spectroscopy of BD+46°442: Gas streams and jet creation in a newly discovered evolved binary with a disk

Gorlova

Winckel

Gielen

et al. 2012

A&A

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Context. Previous studies have shown that many post-asymptotic giant branch (AGB) stars with dusty disks are associated with single-lined binary stars. The inferred orbital separations are too small to accommodate a fully grown AGB star, hence these systems represent a new evolutionary channel that bypasses a full AGB evolution. Aims. We wish to verify the binarity hypothesis for a larger sample establish the nature of the companions, and probe the disk structure and eventually the disk formation mechanisms in binary stars. To achieve these aims, we started a high-resolution spectral monitoring of ∼40 field giants whose binarity had been suspected based on either a light curve, an infrared excess, or a peculiar chemical composition. Methods. Starting from the spring of 2009, we monitored the programme stars with the fibre echelle spectrometer HERMES. We measure their radial velocities (RVs) with a precision of ∼0.2 km s −1 , perform detailed photospheric abundance analyses, and analyse the time-resolved high-resolution spectra to search for line-profile variability.Results. Here we report on the discovery of periodic RV variations in BD+46 • 442, a high Galactic latitude F giant with a disk. We infer that the variations are caused by the motion around a faint companion, and deduce the orbital parameters P orb = 140.77 ± 0.02 d , e = 0.083± 0.002, and a sin i = 0.31 AU. We find that it is a moderately metal-poor star ([M/H] = −0.7) without a strong depletion pattern in its photospheric abundances. Interestingly, many lines indeed show periodic changes with the orbital phase: Hα switches between a double-peak emission line and a P Cyg-like profile, while strong metal lines appear to be split at the maximum redshift. Similar effects are likely visible in the spectra of other post-AGB binaries, but their regularity is not always apparent owing to sporadic observations. We propose that these features result from an ongoing mass transfer from the evolved giant to the companion. In particular, the blueshifted absorption in Hα, which occurs only at superior conjunction, may result from a jet originating in the accretion disk around the companion and that is seen in absorption towards the luminous primary.

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Section: Discussionmentioning

confidence: 99%

Time-resolved spectroscopy of BD+46°442: Gas streams and jet creation in a newly discovered evolved binary with a disk

Gorlova

Winckel

Gielen

et al. 2012

A&A

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“…A review of techniques is given by Marengo (2009). Recent advances include millimeter interferometry of the molecular gas (e.g., Castro-Carrizo et al 2010) and imaging of the thermal dust A&A 551, A110 (2013) emission, in the mid-infrared with ground-based observations (e.g., Lagadec et al 2011) and in the far infrared with Herschel (Decin et al 2011). In this paper, we report progress using a different technique: observing the envelopes in dust-scattered Galactic light.…”

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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“…Results from interferometric observations towards the circumstellar envelopes (CSE) of WFs indicate that, in most cases, the spatial distribution of the detected H 2 O maser components (projected on the plane of the sky) can be correlated with large-scale bipolar structures (e.g. Sahai et al 2005b;Vlemmings et al 2006;Gómez et al 2011;Lagadec et al 2011;Yung et al 2011). …”

Section: Introductionmentioning

confidence: 99%

“…Given the velocity of the spectral features detected, the dynamics of these layers might be a consequence of the passage of a highvelocity outflow throughout the slower and relic AGB wind. Observational tools such as molecular H 2 emission at near infrared wavelengths, radio continuum emission, and both Hydroxyl (OH) and H 2 O maser emission have been used in order to trace the actions of shocks, magnetic fields, and ionized shells on large-scale bipolar structures observed towards post-AGB stars (Sahai et al 2005a;Cerrigone et al 2008;Walsh et al 2009;Bains et al 2009;Lagadec et al 2011;Cerrigone et al 2011;Pérez-Sánchez et al 2013;Tafoya et al 2014;Gonidakis et al 2014;Gledhill & Forde 2015). In the context of the evolution of the CSEs of late-type stars, multi-frequency observational studies of Water Fountain nebulae provide important information regarding the physics behind the shapes of the bipolar structures observed towards more evolved counterparts.…”

Section: Introductionmentioning

confidence: 99%

Deep into the Water Fountains

Pérez-Sánchez

Tafoya

López

et al. 2017

A&A

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Context. The formation of large-scale (hundreds to few thousands of AU) bipolar structures in the circumstellar envelopes (CSEs) of post-Asymptotic Giant Branch (post-AGB) stars is poorly understood. The shape of these structures, traced by emission from fast molecular outflows, suggests that the dynamics at the innermost regions of these CSEs does not depend only on the energy of the radiation field of the central star. Aims. Multi-frequency observations towards a group of post-AGB sources known as Water Fountain nebulae can help to constrain the nature of the mechanism responsible for the launching and collimation of the fast molecular outlflows traced by high-velocity features of H 2 O maser emission. Methods. Deep into the Water Fountains is an observational project based on the results of programs carried out with three telescope facilities: The Karl G. Jansky Very Large Array (JVLA), The Australia Telescope Compact Array (ATCA), and the Very Large Telescope (SINFONI-VLT). Results. Here we report the results of the observations towards the WF nebula IRAS 18043−2116: Detection of radio continuum emission in the frequency range 1.5 GHz -8.0 GHz; H 2 O maser spectral features and radio continuum emission detected at 22 GHz, and H 2 ro-vibrational emission lines detected at the near infrared. Conclusions. The high-velocity H 2 O maser spectral features, and the shock-excited H 2 emission detected could be produced in molecular layers which are swept up as a consequence of the propagation of a jet-driven wind. Using the derived H 2 column density, we estimated a molecular mass-loss rate of the order of 10 −9 M yr −1 . On the other hand, if the radio continuum flux detected is generated as a consequence of the propagation of a thermal radio jet, the mass-loss rate associated to the outflowing ionized material is of the order of 10 −5 M yr −1 . The presence of a rotating disk could be a plausible explanation for the mass-loss rates estimated.

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A mid-infrared imaging catalogue of post-asymptotic giant branch stars★

Cited by 101 publications

References 95 publications

Time-resolved spectroscopy of BD+46°442: Gas streams and jet creation in a newly discovered evolved binary with a disk

Time-resolved spectroscopy of BD+46°442: Gas streams and jet creation in a newly discovered evolved binary with a disk

Deep optical imaging of asymptotic giant branch circumstellar envelopes

Deep into the Water Fountains

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