79,040 research outputs found
Clustered Massive Star Formation in Molecular Clouds
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
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
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
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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