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Binary post-AGB stars are interesting laboratories to study both the evolution of binaries as well as the structure of circumstellar disks. A multiwavelength high angular resolution study of the prototypical object 89 Herculis is performed…

HD 98800 is a nearby hierarchical quadruple system comprising two binaries orbiting each other. Surprisingly, despite its $\sim$ 10 Myr age and dynamic environment, the Ba-Bb component is surrounded by a compact gas-rich disc in a polar…

The Galactic object MWC 137 was suggested to belong to the group of B[e] supergiants. However, with its large-scale optical bipolar ring nebula and the high velocity jet and knots, it is a rather atypical representative of this class. We…

Coronagraphic imaging with the Near Infrared Camera and Multi Object Spectrometer on the Hubble Space Telescope reveals a large, ~400 AU (4'') radius, circumstellar disk around the Herbig Ae/Be star HD 141569. A reflected light image at 1.1…

The post-Asymptotic Giant Branch (AGB) star HR4049 is in an eccentric binary system with a relatively short period probably surrounded by a dusty circumbinary disk. Extremely anomalous oxygen isotopic ratios, O16/O17 ~ O16/O18 ~ 7, have…

Astrophysics · Physics 2009-11-10 Maria Lugaro , Onno Pols , Amanda I. Karakas , Chris A. Tout

Debris disks are the natural by-products of the planet formation process. Scattered or polarized light observations are mostly sensitive to small dust grains that are released from the grinding down of bigger planetesimals. High angular…

On the basis of far-infrared images obtained by the Herschel Space Observatory, we report the discovery of a large and massive dust shell around the yellow hypergiant Hen3-1379 . The nebula appears as a detached ring of 1 pc diameter which…

Solar and Stellar Astrophysics · Physics 2015-06-15 D. Hutsemekers , N. L. J. Cox , C. Vamvatira-Nakou

The presence of disks and outflows is widespread among post-AGB binaries. In the first paper of this series, a surprisingly large fraction of optical light was found to be resolved in the 89 Her post-AGB system. The data showed this flux to…

Solar and Stellar Astrophysics · Physics 2014-09-05 M. Hillen , J. Menu , H. Van Winckel , M. Min , C. Gielen , T. Wevers , G. D. Mulders , S. Regibo , T. Verhoelst

We present Very Large Array observations at 7 mm that trace the thermal emission of large dust grains in the HD 169142 protoplanetary disk. Our images show a ring of enhanced emission of radius ~25-30 AU, whose inner region is devoid of…

We present ALMA continuum and molecular line emission maps at $\sim$1 mm of OH 231.8, a well studied bipolar nebula around an AGB star. The excellent angular resolution of our maps ($\sim$20 mas) allows us to scrutinise the central nebular…

We report the discovery of a circumstellar disk around the young A0 star, HR 4796, in thermal infrared imaging carried out at the W.M. Keck Observatory. By fitting a model of the emission from a flat dusty disk to an image at lambda=20.8…

Astrophysics · Physics 2009-10-30 D. W. Koerner , M. E. Ressler , M. W. Werner , D. E. Backman

Aims: We aim at showing that the broad-band SED characteristics of our sample of post-AGB stars are best interpreted, assuming the circumstellar dust is stored in Keplerian rotating passive discs. Methods: We present a homogeneous and…

Astrophysics · Physics 2009-08-17 S. De Ruyter , H. Van Winckel , T. Maas , T. Lloyd Evans , L. B. F. M. Waters , H. Dejonghe

We aim to study the presence of both rotation and expansion in post-AGB nebulae, in particular around IW Car, a binary post-AGB star that was suspected to be surrounded by a Keplerian disk. We obtained high-quality ALMA observations of 12CO…

Solar and Stellar Astrophysics · Physics 2017-01-04 V. Bujarrabal , A. Castro-Carrizo , H. Van Winckel , C. Sanchez Contreras , M. Santander-Garcia

We present high-dynamic-range images of circumstellar dust around HR 4796A that were obtained with MIRLIN at the Keck II telescope at lambda = 7.9, 10.3, 12.5 and 24.5 um. We also present a new continuum measurement at 350 um obtained at…

Astrophysics · Physics 2014-10-13 Z. Wahhaj , D. W. Koerner , D. E. Backman , M. W. Werner , E. Serabyn , M. E. Ressler , D. C. Lis

In this paper we analyse a set of 33 optical spectra, which were acquired with the ARCES echelle spectrograph (R = 38,000) on the 3.5-m telescope at the Apache Point Observatory. We examine the H{\alpha} profile in each of these…

Solar and Stellar Astrophysics · Physics 2015-06-12 Joshua D. Thomas , Adolf N. Witt , Jason P. Aufdenberg , J. E. Bjorkman , Julie A. Dahlstrom , L. M. Hobbs , Donald G. York

Detailed atmospheric abundances have been calculated for a sample of A-G supergiant stars with IR fluxes and/or high galactic latitudes. HD 172481 and HD 158616 show clear indications of being post-AGB stars that have experienced third…

Astrophysics · Physics 2016-08-16 A. Arellano Ferro , Sunetra Giridhar , P. Mathias

We present diffraction limited (0.6") 24.5micron Subaru/COMICS images of the red supergiant mu Cep. We report the detection of a circumstellar nebula, that was not detected at shorter wavelengths. It extends to a radius of at least 6" in…

We present the first mid-IR long baseline interferometric observations of the circumstellar matter around binary post-AGB stars. Two objects, SX Cen and HD 52961, were observed using the VLTI/MIDI instrument during Science Demonstration…

I propose that the relatively high eccentricity found in some tidally strongly interacting binary systems, where the mass-losing star is an evolved giant star, e.g., an asymptotic giant branch star, is caused by an enhanced mass loss rate…

Astrophysics · Physics 2007-05-23 Noam Soker

We have modelled Atacama Large Millimeter/sub-millimeter Array (ALMA) long baseline imaging of the strong gravitational lens system H-ATLAS J090311.6+003906 (SDP.81). We have reconstructed the distribution of band 6 and 7 continuum emission…