We present mid-infrared (10.4 μm, 11.7 μm, and 18.3 μm) imaging intended to locate and characterize the suspected protostellar components within the Bok globule CB54. We detect and confirm the protostellar status for the near-infrared source CB54YC1-II. The mid-infrared luminosity for CB54YC1-II was found to be Lmidir ≈ 8 L⊙, and we estimate a central source mass of M∗ ≈ 0.8 M⊙ (for a mass accr...

Although stars and planets form in cold environments, X-rays are produced in abundance by young stars. This review examines the implications of stellar X-rays for star and planet formation studies, highlighting the contributions of NASA's (National Aeronautics and Space Administration) Chandra X-ray Observatory. Seven topics are covered: X-rays from protostellar outflow shocks, X-rays from the ...

We report results from numerical simulations of star formation in the early universe that focus on gas at very high densities and very low metallicities. We argue that the gas in the central regions of protogalactic halos will fragment as long as it carries sufficient angular momentum. Rotation leads to the build-up of massive disk-like structures which fragment to form protostars. At metallici...

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...

The first stars in the universe form inside ∼ 106M⊙ dark matter (DM) haloes whose initial density profiles are laid down by gravitational collapse in hierarchical structure formation scenarios. During the formation of the first stars in the universe, the baryonic infall compresses the dark matter further. The resultant dark matter density is presented here, using an algorithm originally develop...

Circularly polarized 3.5 cm continuum emission was detected toward three radio sources in the R CrA region using the Very Large Array. The Class I protostar IRS 5b persistently showed polarized radio emission with a constant helicity over 8 yr, which suggests that its magnetosphere has a stable configuration. There is a good correlation between the Stokes I and Stokes V fluxes, and the fraction...

The origin of brown dwarfs (BDs) is an important component of the theory of star formation, because BDs are approximately as numerous as solar mass stars. It has been suggested that BDs originate from the gravitational fragmentation of protostellar disks, a very different mechanism from the formation of hydrogen burning stars. We propose that BDs are instead formed by the process of turbulent f...

We have carried out a submillimeter continuum and spectroscopic study of the W43 main complex, a massive star-forming region, which harbors a giant H ii region. The maps reveal a filamentary structure containing ∼ 50 fragments with masses of 40− 4 000 M⊙ and typical diameters of 0.25 pc. Their large sizes, large non-thermal velocities (∆v ∼ 5 km s), and high densities (nH2 ∼ 10 6 cm) suggest th...

Forming stars emit a substantial amount of radiation into their natal environment. We use ORION, an adaptive mesh refinement (AMR) three-dimensional gravito-radiation-hydrodyanics code, to simulate low-mass star formation in a turbulent molecular cloud. We compare the distribution of stellar masses, accretion rates, and temperatures in the cases with and without radiative transfer, and we demon...

When observed with sufficiently high spatial resolution and sensitivity, star formation regions are unusually complex X-ray sources. Low-mass protostars and T Tauri stars, Herbig Ae/Be stars, OB and Wolf-Rayet stars are seen at levels 28 ≤ logLx ≤ 34 erg/s. Highamplitude variability from magnetic reconnection flares are often present. From past star formation episodes, supernova remnants and X-...