Young stars form on a wide range of scales, producing aggregates and clusters with various degrees of gravitational self-binding. The loose aggregates have a hierarchical structure in both space and time that resembles interstellar turbulence, suggesting that these stars form in only a few turbulent crossing times with positions that map out the previous gas distribution. Dense clusters, on the...

The association between star-forming regions and X-ray emission was discovered over 30 years ago. We now know that essentially all young stellar objects, T Tauri stars and protostars, are X-ray emitters, although the case of the youngest, Class 0 protostars, is less clear. The paper highlights X-ray emission and absorption mechanisms, and summarizes X-ray observations of young stellar objects. ...

We report the direct detection of a binary/disk system towards the highmass (proto)stellar object IRAS20126+4104 at infrared wavengths. The presence of a multiple system had been indicated by the precession of the outflow and the double jet system detected earlier at cm-wavelengths. Our new K, L & M band infrared images obtained with the UKIRT under exceptional seeing conditions on Mauna Kea ar...

We present the results of an extensive 1.3 mm continuum mosaicing study of the ρ Ophiuchi central region obtained at the IRAM 30-m telescope with the MPIfR 19–channel bolometer array. The mosaiced field covers a total area of ∼ 480 arcmin2, corresponding to ∼ 1 pc2 at a distance of 160 pc, and includes the DCO dense cores Oph-A, Oph-B1, Oph-B2, Oph-C, Oph-D, Oph-E, and Oph-F. Our mosaic is sens...

The infrared represents an alternative wavelength regime in which to study the environments of maser emission, while at the same time complementing the information obtained through radio techniques. The near infrared (1-2 μm) yields information on outflows, shocks, and reflected dust emission, while the thermal infrared (3-30 μm) yields information on the thermal dust distribution around stars....

We present the results of an interferometric study of the N2H + (1–0) emission from nine nearby, isolated, low-mass protostellar cores, using the OVRO millimeter array. The main goal of this study is the kinematic characterization of the cores in terms of rotation, turbulence, and fragmentation. Eight of the nine objects have compact N2H + cores with FWHM radii of 1200 − 3500 AU, spatially coin...

We develop a new method to identify YSOs from star-forming regions using the photometry data from Spitzer’s c2d Legacy Project. The aim is to obtain YSO lists as complete as possible for studying the statistical properties, such as Star Formation Rate (SFR) and lifetimes of YSOs in different evolutionary stages. The largest obstacle for identifying YSOs comes from background galaxies with simil...

We report the results of a deep near infrared (JHK) survey of the outer parts of the Trapezium Cluster with Gemini South/Flamingos. 396 sources were detected in a 26 arcmin area, including 138 brown dwarf candidates, defined as M< 0.075M⊙ for an assumed age of 1 Myr. Only 33 of the brown dwarf candidates are planetary mass candidates (PMCs) with estimated masses in the range 0.003 <M< 0.012M⊙. ...

The ejection of prodigious amounts of material during birth still puzzles us. It is paradoxical that just when we expect to observe infall, the signatures of outflow prevail. Ultimately, we want to know why. Are we witnessing simply the disposal of waste material – the placenta being cast aside? Or are outflows essential, a means of removing some ingredient which allows the rest to flow inwards...