Related papers: Second-generation protoplanetary discs around evol…

As mass-losing asymptotic giant branch (AGB) stars evolve to planetary nebulae (PNe), the mass outflow geometries transform from nearly spherical to extreme aspherical. The physical mechanisms governing this transformation are widely…

A new type of peculiarity -- a splitting or asymmetry of strong absorption lines, is found in the optical spectra of selected post-AGB stars with C-rich circumstellar envelopes. The effect is maximal in BaII lines whose profile is split…

Context. When low and intermediate-mass stars leave the Asymptotic Giant Branch (AGB) phase, and before they reach the Planetary Nebulae stage, they enter a very brief and rather puzzling stellar evolutionary stage named post-AGB. Aims. To…

Substructures in disc density are ubiquitous in the bright extended discs that are observed with high resolution. These substructures are intimately linked to the physical mechanisms driving planet formation and disc evolution. Surveys of…

We present a 3-5um LBT/MMT adaptive optics imaging study of three Upper Scorpius stars with brown dwarf (BD) companions with very low-masses/mass ratios (M_BD < 25M_Jup; M_BD / M_star ~ 1-2%), and wide separations (300-700 AU): GSC 06214,…

It is currently admitted that an AGB star in a binary system is likely to pollute its companion with carbon- and s-process-rich matter. After the AGB star has faded into an unconspicuous white dwarf, the polluted companion enters the zoo of…

Be/X-ray binaries are the most numerous group of high-mass X-ray binaries. Their long-term optical and infrared variability reflects the evolution of the circumstellar disk around the luminous companion. This variability manifests…

The formation of multiple stellar systems is a natural by-product of the star-formation process, and its impact on the properties of protoplanetary discs and on the formation of planets is still to be fully understood. To date, no detailed…

The INT Photometric H-Alpha Survey (IPHAS) is particular effective in tracing asymptotic giant branch (AGB) stars across the Galactic disk due to its use of broad-band r' and i' filters, and the clear separation of the dwarf and giant…

Nearly all young stars are initially surrounded by `protoplanetary' discs of gas and dust, and in the case of single stars at least 30\% of these discs go on to form planets. The process of protoplanetary disc formation can result in…

Recent observations of strikingly well-defined spirals in the circumstellar envelopes of asymptotic giant branch (AGB) stars point to the existence of binary companions in these objects. In the case of planet or brown dwarf mass companions,…

During their thermally pulsing phase, Asymptotic Giant Branch (AGB) stars eject material that forms extended dusty envelopes. Visible polarimetric imaging found clumpy dust clouds within two stellar radii of several oxygen-rich stars.…

Recently available near-infrared interferometric data on late-type stars show a strong increase of diameter for asymptotic giant branch (AGB) stars between the K (2.0 - 2.4 \mu m) and L (3.4 - 4.1 \mu m) bands. Aiming at an explanation of…

Obscured by their circumstellar dusty envelopes post-AGB stars emit a large fraction of their energy in the infrared and thus, infrared sky surveys like IRAS were essential for discoveries of post-AGBs in the past. Now, with the AKARI…

Previous studies have shown that many post-AGB stars with dusty disks are associated with single-lined binary stars. To verify the binarity hypothesis on a larger sample, we started a high-resolution spectral monitoring of about 40 field…

We present a long-term optical spectroscopic study of the post-AGB binary system 89 Herculis, with the aim to characterize the relationship between photospheric instabilities and dynamics in the close circumstellar environment of the…

Semi-regular (SR) variables are not a homogeneous class and their variability is often explained due to pulsations and/or binarity. This study focuses on IRAS 19135+3937, an SRd variable with an infra-red excess indicative of a dusty disc.…

Mid-infrared imaging traces the sub-micron and micron sized dust grains in protoplanetary disks and it offers constraints on the geometrical properties of the disks and potential companions, particularly if those companions have…

All four circumbinary (CB) protoplanetary disks orbiting short-period ($P < 20$ day) double-lined spectroscopic binaries (SB2s)---a group that includes UZ Tau E, for which we present new ALMA data---exhibit sky-plane inclinations $i_{\rm…

The innermost astronomical unit in protoplanetary disks is a key region for stellar and planet formation, as exoplanet searches have shown a large occurrence of close-in planets that are located within the first au around their host star.…