We present results of a sensitive 76 ksec Chandra observation of the young stellar cluster in NGC 2024, lying at a distance of ∼415 pc in the Orion B giant molecular cloud. Previous infrared observations have shown that this remarkable cluster contains several hundred embedded young stars, most of which are still surrounded by circumstellar disks. Thus, it presents a rare opportunity to study X...

Abstract We present Atacama Large Millimeter/submillimeter Array observations of the ∼10,000 au environment surrounding 21 protostars in Orion A molecular cloud tracing outflows. Our sample is composed Class 0 to flat-spectrum protostars, spanning full ∼1 Myr lifetime. derive angular distribution outflow momentum and energy profiles obtain first two-dimensional instantaneous mass, momentum, eje...

We present results from an extensive spectroscopic survey in the 3-5μm wavelength region of low-mass young stellar objects using VLT-ISAAC. Medium resolution spectra (λ/∆λ ∼ 1 000 − 10 000) of young embedded stars in the mid-infrared allow for detailed studies of ro-vibrational lines from molecular gas, interstellar ices and Polycyclic Aromatic Hydrocarbons (PAHs). By taking advantage of this w...

Cold molecular clouds are the birthplaces of stars and planets, where dense cores of gas collapse to form protostars. The dust mixed in these clouds is thought to be made of grains of an average size of 0.1 micrometer. We report the widespread detection of the coreshine effect as a direct sign of the existence of grown, micrometer-sized dust grains. This effect is seen in half of the cores we h...

Recent near-IR observations of Herbig-Haro (HH) jets and molecular outflows from very young, deeply embedded protostars are discussed. Proper motion measurements, and both lowand high-resolution spectroscopic studies reveal the excitation and kinematics of individual objects, which may be interpreted in terms of highvelocity bow shocks which sweep up and entrain ambient material to form molecul...

We present a study of molecular outflows using high-resolution mapping of the CO (1-0) line emission toward eight relatively nearby 6.7 GHz methanol masers, which are associated with massive star forming regions. Outflows were detected in seven out of eight sources, and five of them clearly show bipolar or multiple outflow morphologies. These outflows have typical masses of a few solar masses, ...

The characteristic signature of Be stars is the Balmer line emission understood to arise in a circumstellar disk. Unlike the accretion disks of protostars or mass-exchange binary systems, the evolved and generally single or wide-binary status of Be stars seems to require that its disk must form from mass ejection (a.k.a. decretion) from the star itself. In this paper, I use analogies with launc...

We present a high spatial resolution multi-wavelength survey of 44 young binary star systems in Taurus-Auriga with separations of 10 1000 AU. These observations, which were obtained using the Hubble Space Telescope and the NASA Infrared Telescope Facility, quadruple the number of close (< 100 AU) binary stars with spatially resolved measurements from 0.3 to 2.2 μm and are the first 3.6 μmmeasur...

Methanol lines observations of a sample of low mass Class 0 protostars are presented. Using a 1D radiative transfer model, I show that several protostars have large abundance jumps in the inner hot and dense region of envelopes, probably because of thermal grain mantle evaporation. These abundances are compared with a grain surface chemistry model.