Presolar grains in meteorites formed in a sample of AGB stars that ended their lives within ≈1 Gyr of the origin of the Solar System 4.6 Gyr ago. The O-isotopic compositions of presolar O-rich stardust reflect the masses and metallicities of their parent stars. We present simple Monte Carlo simulations of the parent AGB stars of presolar grains. Comparison of model predictions with the grain da...

The remarkably filamentary spatial distribution of young stars in the Taurus molecular cloud has significant implications for understanding low-mass star formation in relatively quiescent conditions. The large scale and regular spacing of the filaments suggests that small-scale turbulence is of limited importance, which could be consistent with driving on large scales by flows which produced th...

We model the formation of high-mass stars, specifying the accretion rate in terms of the instantaneous and final mass of the star, the ambient pressure of the star-forming region and the form of polytropic pressure support of the pre-stellar gas core. The high pressures typical of Galactic regions of massive star formation allow a 100 M⊙ star to form in ∼ 105 yr with a final accretion rate ∼ 10...

We characterize protostellar multiplicity in the Orion molecular clouds using ALMA 0.87~mm and VLA 9~mm continuum surveys toward 328 protostars. These observations are sensitive to projected spatial separations as small $\sim$20~au, we consider source up 10$^4$~au potential companions. The overall fraction (MF) companion (CF) for protostars 0.30$\pm$0.03 0.44$\pm$0.03, respectively, considering...

We investigate the alignment between outflow axes in nine of the youngest binary/multiple systems in the Perseus Molecular Cloud. These systems have typical member spacing larger than 1000 AU. For outflow identification, we use CO(2-1) and CO(3-2) data from a large survey with the Submillimeter Array: Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES). The distribution o...

We present colour-colour and colour-magnitude diagrams for RCW 57 (NGC 3576) based on L-band data at 3.5 μm taken with SPIREX (South Pole Infrared Explorer), and 2MASS JHKs data at 1.25-2.2 μm. A total of 251 sources were detected. More than 50% of the 209 sources included in the diagrams have an infrared excess. The IR-excess is interpreted as coming from circumstellar disks and hence gives th...

Introduction: Carbonates have been recently detected in dust shells of evolved stars [1] and protostars [2,3] suggesting that they could form under dry conditions (without liquid water). Around young stars, silicates are mainly magnesium-rich, amorphous and porous dusts [4], believed to form in the interstellar medium (ISM) by irradiation [5]. Such material is far from equilibrium and potential...

In an effort to shed more light on the formation process of binary stars, we have started a program to study multiplicity among nearby low-and intermediate-mass protostars using the OVRO Millimeter Array. Here, we describe the project and present the first results on the protostellar core in the Bok globule CB 230 (L 1177). At 10 ′′ resolution , the molecular core is resolved into two component...

We observed the HH24-26 region in the L1630 Orion molecular cloud complex with the X-ray observatory ASCA in the 0.5−10 keV band. X-ray emission was detected from the T Tauri star SSV61 and from the region where the Class I protostars SSV63E and SSV63W are located (hereafter SSV63E+W). The spectra of both SSV63E+W and SSV61 are well explained by an optically thin thermal plasma model. The spect...