Related papers: Bipolar outflows in OH/IR stars
We present the results of a near-infrared monitoring programme of a selected sample of stars, initially suspected to be Mira variables and OH/IR stars, covering more than a decade of observations. The objects monitored cover the typical…
In the late stage of their evolution, low- to intermediate-mass stars pass through the asymptotic giant branch (AGB) phase, characterised by strong mass loss through dust driven winds. High angular resolution observations reveal that these…
In this paper we study the near-infrared emission spectrum of IRAS 16594-4656, a bipolar post-AGB star with spectral type B7 and no observed ionization. Using optical and near-infrared photometry we determined the total extinction towards…
The hydrogen-deficiency in extremely hot post-AGB stars of spectral class PG1159 is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse that consumes the hydrogen envelope, exposing the usually-hidden intershell…
An analysis of high-resolution near-infrared spectra of a sample of 45 asymptotic giant branch (AGB) stars towards the Galactic bulge is presented. The sample consists of two subsamples, a larger one in the inner and intermediate bulge, and…
We present our recent results on mm-wave CO observations of proto-planetary nebulae. These include high-resolution interferometric maps of various CO lines in three well known bipolar PPNe: M1-92, M2-56 and OH231.8+4.2. The global…
There is a growing number of observational indicators for the presence of bipolar outflows in massive, young stellar objects that are still accreting mass as part of their formation process. In particular, there is evidence that the…
We report optical long-slit spectra and direct imaging (ground-based and with HST) of the pre-planetary nebula (pPN) M2-56 obtained at different epochs. The optical nebula is composed by shock-excited material distributed in two pairs of…
Lithium and zirconium abundances (the latter taken as representative for s-process enrichment) are determined for a large sample of massive Galactic O-rich AGB stars, for which high resolution optical spectroscopy has been obtained…
We have carried out a new photometric V,Rc study of 12 protoplanetary nebulae, objects in the short-lived transition between the AGB and PN phases of stellar evolution. These had been the subjects of an earlier study, using data from…
The Mass loss of Evolved StarS (MESS) sample offers a selection of 78 Asymptotic Giant Branch (AGB) stars and Red Supergiants (RSGs) observed with the PACS photometer on-board Herschel at 70 and 160 {\mu}m. For most of these objects, the…
We investigate the properties of AGB and post-AGB (PAGB) stars, planetary nebulae, and young stellar objects (YSOs) in our Galaxy through an analysis of observational data covering visual and infrared (IR) wavelengths. Utilizing datasets…
We present observations of 86 post-Asymptotic Giant Branch (post-AGB) stars of OH maser transitions, taken with the Parkes Telescope between September 2002 and August 2003. Post-AGB stars are the precursors of planetary nebulae, which have…
We investigate mass transfer and the formation of disc in binary systems using a combination of numerical simulations and theory. We consider six models distinguished by binary separation, secondary mass and outflow mechanisms. Each system…
We present new optical broad-band (UBVRI) aperture polarimetric observations of 53 post-asymptotic giant branch (AGB) stars selected to exhibit a large near-infrared excess. 24 out of the 53 stars (45% of our sample) are presented for the…
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…
Asymptotic giant branch (AGB) stars are known to lose a significant amount of mass by a stellar wind, which controls the remainder of their stellar lifetime. High angular-resolution observations show that the winds of these cool stars…
The geometrical relationship between the distribution of circumstellar matter, observed optical linear polarization, outflows and binary orbital plane in Herbig Ae/Be stars is investigated. Optical linear polarization measurements carried…
The bipolar nebula, IRAS 19312+1950, is a unique SiO maser source exhibiting both properties as young and evolved objects. To clarify the nature of this object, we made molecular line observations with the Nobeyama 45-m radio telescope. We…
The near-star environment around obscured stars is very dynamic. Many classes of stars show evidence for winds, disks, inflows and outflows with many phenomena occurring simultaneously. These processes are involved in stellar evolution,…