78,625 research outputs found

    Clustered Massive Star Formation in Molecular Clouds

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    I review some important questions in the field of massive star formation: What are the initial conditions for proto star clusters and how do they arise? What are the initial conditions for individual massive star formation within star clusters? How do massive protostars accumulate their mass? I compare the Turbulent Core Model (McKee & Tan 2003) to several nearby regions, including Orion KL. Here I also discuss the origin of BN's high proper motion.Comment: 10 pages, 2 figures, invited review, to appear in "Massive Star Birth - A Crossroads of Astrophysics" (CUP), eds. R. Cesaroni, E. Churchwell, M. Felli, and C. M. Walmsle

    Fire from Ice - Massive Star Birth from Infrared Dark Clouds

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    I review massive star formation in our Galaxy, focusing on initial conditions in Infrared Dark Clouds (IRDCs), including the search for massive pre-stellar cores (PSCs), and modeling of later stages of massive protostars, i.e., hot molecular cores (HMCs). I highlight how developments in astrochemistry, coupled with rapidly improving theoretical/computational and observational capabilities are helping to improve our understanding of the complex process of massive star formation.Comment: To appear in proceedings of IAU Symp. 322, Astrochemistry VII Through the Cosmos from Galaxies to Planet

    Parametrized energy spectrum of cosmic-ray protons with kinetic energies down to 1 GeV

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    A new estimation of the interstellar proton spectrum is made in which the source term of primary protons is taken from shock acceleration theory and the cosmic ray propagation calculation is based on a proposed nonuniform galactic disk model

    Analysis of experimental data on interstellar antiprotons in the light of measurements of high-energy electrons and He-3 nuclei

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    The interstellar antiproton calculations were reexamined in view of the recent progress in measurements of interstellar electrons and He(3) nuclei. It was found that the divergence between the predicted antiproton flux and the existing datum at very low energies is increased. The proposed nonuniform galactic disk (NUGD) model qualitatively explains the unexpectedly large flux of interstellar antiprotons. Some ambiguities existed in the prototype of the model. It was unclear what fraction of observed antiprotons is of local origin. Previously the value of cosmic ray escape pathlength was suggested with quite a large arbitrariness
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