If massive stars form by disk accretion, then bipolar outflows should be generated as in the case of low-mass star formation. High accretion rates lead to high outflow rates and make the wind density very large near the protostar. We therefore predict that massive protostars have very small, jet-like H II regions confined by their outflows; we identify these H II regions with “hypercompact” (≤ ...

We present 1.3mm continuum and CS J = 5 → 4 maps at 12′′ resolution of the NGC1333 star forming region. The area covered is 8′ × 6′. The large-scale bolometer and CS maps delineate very nicely the large central cavity together with the cores situated in the surrounding compressed shell. In addition to the four dust cores IRAS4A-B, IRAS2 and SVS13, we discovered two fainter condensations, one of...

Abstract One critical remaining issue that is unclear in the initial mass function of first (Population III) stars final fate secondary protostars formed accretion disk—specifically, whether they merge or survive. We focus on magnetic effects formation star under a cosmological field. perform suite ideal magnetohydrodynamic simulations for 1000 yr after protostar formation. Instead sink particl...

Observations of stars in the vicinity of the Sun show that binary systems are prevalent and appear to be a general outcome of the star-formation process. One of the major goals of this research is to understand the nature of the formation of binary and multiple stellar systems with typical low-mass stars (∼ 0.2 to 3 M ) and the physical properties of these systems. Basic questions concerning th...

We present observations of the giant HII region complex N159 in the LMC using IRAC on the Spitzer Space Telescope. One of the two objects previously identified as protostars in N159 has an SED consistent with classification as a Class I young stellar object (YSO) and the other is probably a Class I YSO as well, making these two stars the youngest stars known outside the Milky Way. We identify t...

Context. The CrA region and the Coronet cluster form a nearby (138 pc), young (1−2 Myr) star-forming region that hosts a moderate population of Class I, II, and III objects. Aims. We study the structure of the cluster and the properties of the protostars and protoplanetary disks in the region. Methods. We present Herschel PACS photometry at 100 and 160 μm, obtained as part of the Herschel Gould...

We present evolutionary models for young low mass stars and brown dwarfs taking into account episodic phases of accretion at early stages of the evolution, a scenario supported by recent large surveys of embedded protostars. An evolution including short episodes of vigorous accretion (Ṁ ≥ 10−4M yr−1) followed by longer quiescent phases (Ṁ < 10−6M yr−1) can explain the observed luminosity spread...

Young protostars embedded in circumstellar discs accrete from an angular momentum rich mass reservoir. Without some braking mechanism, all stars should be spinning at or near breakup velocity. In this paper, we perform simulations of the self-gravitational collapse of an isothermal cloud using the ORION adaptive-mesh refinement code and investigate the role that gravitational torques might play...

This is a report on detailed modeling of young high-mass protostellar candidates during their most embedded and obscured phases. We performed narrowband mid-infrared imaging of three candidate high-mass protostellar objects in G11.94-0.62, G29.96-0.02, and G45.07+0.13 at Gemini Observatory using the Thermal-Region Camera and Spectrograph (T-ReCS). The sources were imaged through up to 11 narrow...

Although the space between stars in our galaxy appears to be completely empty of matter, there exists a very dilute gas even in “empty” space. This interstellar (meaning “between the stars”) medium varies in density (the amount of matter within a certain volume). Typical densities in the interstellar medium are one particle per cubic centimeter. Since hydrogen is the most single common element ...