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There is a class of binary post-AGB stars that are surrounded by Keplerian disks and that often present outflows resulting from gas escaping from the disk. We present maps and complex models of 12CO and 13CO J=2-1 emission lines for four…

Solar and Stellar Astrophysics · Physics 2023-11-15 Iván Gallardo Cava

There is a class of binary post-asymptotic giant branch (post-AGB) stars that exhibit remarkable near-infrared (NIR) excess. These stars are surrounded by disks with Keplerian or quasi-Keplerian dynamics and outflows composed of gas…

Solar and Stellar Astrophysics · Physics 2023-03-08 I. Gallardo Cava , J. Alcolea , V. Bujarrabal , M. Gómez-Garrido , A. Castro-Carrizo

There is a class of binary post-AGB stars with a remarkable near-infrared excess that are surrounded by Keplerian or quasi-Keplerian disks and extended outflows composed of gas escaping from the disk. The Keplerian dynamics had been well…

Solar and Stellar Astrophysics · Physics 2021-04-21 I. Gallardo Cava , M. Gómez-Garrido , V. Bujarrabal , A. Castro-Carrizo , J. Alcolea , H. Van Winckel

There is a group of post-AGB stars that are part of a binary system and that show a significant NIR excess. These systems are known to host disks with Keplerian or quasi-Keplerian dynamics and to drive outflows of gas escaping from the…

Solar and Stellar Astrophysics · Physics 2025-12-01 I. Gallardo Cava , J. Alcolea , H. Van Winckel , V. Bujarrabal , M. Santander-García , M. Gómez-Garrido

Context. There is a class of binary post-asymptotic giant branch (post-AGB) stars that exhibit remarkable near-infrared (NIR) excess. Such stars are surrounded by Keplerian or quasi-Keplerian disks, as well as extended outflows composed of…

Solar and Stellar Astrophysics · Physics 2022-04-20 I. Gallardo Cava , V. Bujarrabal , J. Alcolea , M. Gómez-Garrido , M. Santander-García

So far, only one rotating disk has been clearly identified and studied in AGB or post-AGB objects (in the Red Rectangle), by means of observations with high spectral and spatial resolution. However, disks are thought to play a key role in…

Solar and Stellar Astrophysics · Physics 2015-02-25 V. Bujarrabal , A. Castro-Carrizo , J. Alcolea , H. Van Winckel

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 are studying a class of binary post-AGB stars that seem to be systematically surrounded by equatorial disks and slow outflows. Although the rotating dynamics had only been well identified in three cases, the study of such structures is…

Solar and Stellar Astrophysics · Physics 2018-06-13 V. Bujarrabal , A. Castro-Carrizo , H. Van Winckel , J. Alcolea , C. Sanchez Contreras , M. Santander-Garcia , M. Hillen

There is a group of binary post-AGB stars that show a conspicuous NIR excess, usually assumed to arise from hot dust in very compact possibly rotating disks. These stars are surrounded by significantly fainter nebulae than the "standard",…

Astrophysics of Galaxies · Physics 2015-06-16 V. Bujarrabal , J. Alcolea , H. Van Winckel , M. Santander-Garcia , A. Castro-Carrizo

We aim to study equatorial disks in rotation and axial outflows in post-AGB objects, as to disclose the formation and shaping mechanisms in planetary nebulae. So far, both disks and outflows had not been observed simultaneously. We have…

We present new high-quality ALMA observations of the Red Rectangle (a well known post-AGB object) in C17O J=6-5 and H13CN J=4-3 line emission and results from a new reduction of already published 13CO J=3-2 data. A detailed model fitting of…

Solar and Stellar Astrophysics · Physics 2016-10-05 V. Bujarrabal , A. Castro-Carrizo , J. Alcolea , M. Santander-Garcia , H. Van Winckel , C. Sanchez Contreras

We aim to study the structure of the nebula around the post-AGB, binary star 89 Her. The presence of a rotating disk around this star had been proposed but not been yet confirmed by observations. We present high-resolution PdBI maps of CO…

Astrophysics · Physics 2009-11-13 V. Bujarrabal , H. Van Winckel , R. Neri , J. Alcolea , A. Castro-Carrizo , P. Deroo

The Red Rectangle is a nebula surrounding the post-AGB star HD 44179. It is the prototype of a particular class of nebulae associated with post-AGB binaries characterised by the presence of stable circumbinary disks in (quasi-)Keplerian…

We investigate the development of bipolar outflows during the early post-AGB evolution. A sample of ten OH/IR stars is observed at high angular resolution, including bipolar nebulae (OH231.8+4.2), bright post-AGB stars (HD 101584) and…

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…

In this contribution we give a progress report on our systematic study of a large sample of post-AGB stars. The sample stars were selected on the basis of their infrared colours and the selection criteria were tuned to discover objects with…

Astrophysics · Physics 2007-05-23 Hans Van Winckel , Tom Lloyd Evans , Maarten Reyniers , Pieter Deroo , Clio Gielen

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…

Many aspects of the evolutionary phase in which Asymptotic Giant Branch stars (AGB stars) are in transition to become Planetary Nebulae (PNe) are still poorly understood. An important question is how the circumstellar envelopes of AGB stars…

Solar and Stellar Astrophysics · Physics 2019-08-14 L. Cerrigone , K. M. Menten , T. Kaminski

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 dust distribution in the central regions of the Keplerian disk of the Red Rectangle, the prototype of binary post-AGB stars with rotating circumbinary disks, and to compare it with the distribution of relevant molecular…

Solar and Stellar Astrophysics · Physics 2023-09-15 V. Bujarrabal , J. Alcolea , A. Castro-Carrizo , J. Kluska , C. Sanchez Contreras , H. Van Winckel
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