Related papers: Salt-bearing disk candidates around high-mass youn…
We present K-band polarimetric images of several massive young stellar objects at resolutions $\sim$ 0.1-0.5 arcsec. The polarization vectors around these sources are nearly centro-symmetric, indicating they are dominating the illumination…
Context. This paper discusses the sensitivity of water lines to chemical processes and radiative transfer for the protoplanetary disk around TW Hya. The study focuses on the Herschel spectral range in the context of new line detections with…
We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution ($R\sim$ 6000) spectra of these stars to estimate…
Context - Circumstellar discs are ubiquitous around young stars, but rapidly dissipate their gas and dust on timescales of a few Myr. The Herschel space observatory allows for the study of the warm disc atmosphere, using far-infrared…
We carried out a 12CO(3-2) survey of 52 southern stars with a wide range of IR excesses (LIR/L*) using the single dish telescopes APEX and ASTE. The main aims were (1) to characterize the evolution of molecular gas in circumstellar disks…
Water is a key species in many astrophysical environments, but it is particularly important in proto-planetary disks. So far,observations of water in these objects have been scarce, but the situation should soon change thanks to the…
Single-dish spectra and interferometric maps of (sub)mm lines of H2O-18 and HDO are used to study the chemistry of water in eight regions of high-mass star formation. The spectra indicate HDO excitation temperatures of ~110 K and column…
Debris discs have often been described as gas-poor discs as the gas-to-dust ratio is expected to be considerably lower than in primordial,protoplanetary discs. However, recent observations have confirmed the presence of a non-negligible…
BP Psc is a puzzling late-type, emission-line field star with large infrared excess. The star is encircled and enshrouded by a nearly edge-on, dust circumstellar disk, and displays an extensive jet system similar to those associated with…
The results of a survey searching for outflows using near-infrared imaging is presented. Targets were chosen from a compiled list of massive young stellar objects (YSOs) associated with methanol masers in linear distributions. Presently, it…
We report on the observation of hot water vapor (steam) in the inner AU of a young massive star located in the star-forming region IRAS 08576-4334. The water lines are detected in a medium resolution (R=10,000) K-band spectrum taken by the…
We present an analysis of high-resolution spectroscopy of several bright T Tauri stars using the VLT/CRIRES and Keck/NIRSPEC spectrographs, revealing the first detections of emission from HCN and C2H2 in circumstellar disks at near-infrared…
Maser lines from different molecular species, including water, hydroxyl, and methanol, are common observational phenomena associated with massive star forming regions. In particular, the methanol maser appears as an ideal tool to study the…
Context: The Red MSX Source (RMS) survey has identified a large sample of candidate massive young stellar objects (MYSOs) and ultra compact (UC) HII regions from a sample of ~2000 MSX and 2MASS colour selected sources. Aims: To search for…
We present radio and infrared observations indicating on-going star formation activity inside the $\sim2-5$ pc circumnuclear ring at the Galactic center. Collectively these measurements suggest a continued disk-based mode of on-going star…
Circumstellar disks are an essential ingredient of the formation of low-mass stars. It is unclear, however, whether the accretion-disk paradigm can also account for the formation of stars more massive than about 10 solar masses, in which…
Circumstellar disks provide the material reservoir for the growth of young stars and for planet formation. We combine a high-level radiative transfer program with a thermal-chemical model of a typical T Tauri star disk to investigate the…
Planet-forming disks around brown dwarfs and very low-mass stars (VLMS) are on average less massive and are expected to undergo faster radial solid transport than their higher mass counterparts. Spitzer had detected C$_2$H$_2$, CO$_2$ and…
Debris disks are exoplanetary systems that contain planets, minor bodies (i.e., asteroids, Kuiper belt objects, comets, etc.), and micron-sized debris dust. Since water ice is the most common frozen volatile, it plays an essential role in…
There have been several recent detections of candidate Keplerian discs around massive young protostars. Given the relatively large disc-to-star mass ratios in these systems, and their young ages, it is worth investigating their propensity…