We have observed the W75 N massive star forming region in SiO(J=2–1 & J=1–0) at 3′′ − 5′′ resolution and in 6 cm, 2 cm, and 7 mm continuum emission at 1.4′′ − 0.2′′ resolution. The abundance ratio of [SiO]/[H2] ∼ 5 − 7 × 10−11 which is typical for what is expected in the ambient component of molecular clouds with active star formation. The SiO morphology is diffuse and centered on the positions...

We describe near-IR imaging data for a sample of 23 Class I sources in the Taurus-Auriga dark clouds. Combining our data with previous photometry, we detect brightness variations of 0.1–0.5 mag in many sources. The near-IR morphologies are consistent with millimeter continuum measurements. Most ( 60%) of the sample are true protostars; the rest may be objects in transition between Class I and C...

Recent observations of nearby star forming regions have offered evidence that young brown dwarfs undergo a period of mass accretion analogous to the T Tauri phase observed in young stars. Brown dwarf analogs to stellar protostars, however, have yet to be definitively observed. These young, accreting objects would shed light on the nature of the dominant brown dwarf formation process, as well as...

Context. Molecular clouds near the H  regions tend to harbor more luminous protostars. Aims. Our aim in this paper is to investigate whether or not radiation-driven implosion mechanism enhances luminosity of protostars near regions of high-ionizing fluxes. Methods. We performed numerical simulations to model collapse of cores exposed to UV radiation from O stars. We investigated dependence of...

It is expected that an average protostar will undergo at least one impulsive interaction with a neighbouring protostar whilst a large fraction of its mass is still in a massive, extended disc. If protostars are formed individually within a cluster before falling together and interacting, there should be no preferred orientation for such interactions. As star formation within clusters is believe...

As Pr. Th. Henning said at the conference, cold precursors of high-mass stars are now “hot topics”. We here propose some observational criteria to identify massive infrared-quiet dense cores which can host the highmass analogs of Class 0 protostars and pre-stellar condensations. We also show how far-infrared to millimeter imaging surveys of entire complexes forming OB stars are starting to unve...

Disk accretion onto magnetic stars occurs in a variety of systems, including accreting neutron stars (with both high and low magnetic fields), white dwarfs, and protostars. We review some of the key physical processes in magnetosphere-disk interaction, highlighting the theoretical uncertainties. We also discuss some applications to the observations of accreting neutron star and protostellar sys...

We compare the infrared colors predicted by theoretical models of protostellar envelopes and protoplanetary disks with initial observations of young stellar objects made with the Infrared Array Camera ( IRAC) on the Spitzer Space Telescope. Disk and envelope models characterized by infall and/or accretion rates found in previous studies can quantitatively account for the range of IRAC colors fo...

Observations of Lynds Dark Nebula 1221 from the Spitzer Space Telescope are presented. These data show three candidate protostars towards L1221, only two of which were previously known. The infrared observations also show signatures of outflowing material, an interpretation which is also supported by radio observations with the Very Large Array. In addition, molecular line maps from the Five Co...

In this study I present new K and L-band infrared photometry and 2-4μm spectra of ten Class I and flat spectrum stars forming within the Taurus dark cloud complex. Nine sources have H2 v=0-1 S(1) emission, and some show multiple H2 emission features in their K-band spectra. Photospheric absorptions characteristic to low mass stars are detected in five of the targets, and these stars were fit wi...