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Doctoral Dissertations

2019

Star formation

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Full-Text Articles in Stars, Interstellar Medium and the Galaxy

Observational Studies Of Fragmentation In Molecular Clouds, Riwaj Pokhrel Oct 2019

Observational Studies Of Fragmentation In Molecular Clouds, Riwaj Pokhrel

Doctoral Dissertations

In this dissertation, I explore fragmentation physics in multiple scales in nearby molecular clouds and discuss some implications of fragmentation for cloud structure formation and star formation, primarily by analyzing multi-wavelength observations of dust emission. First, I tested the complete thermal and combined thermal and nonthermal support mechanisms that balance gravitational contraction at multiple scales in the Perseus molecular cloud. I found that the observed multiscale structures in Perseus are consistent with an inefficient thermal Jeans fragmentation, where the Jeans efficiency increases from the largest scale ($\gtrsim$10s of pc) to the smallest scale ($\sim$10s of AU). Next, I studied the …


The Impact Of Protostellar Feedback On Astrochemistry, Brandt Gaches Oct 2019

The Impact Of Protostellar Feedback On Astrochemistry, Brandt Gaches

Doctoral Dissertations

Star formation is the lynch pin that lies in between the scales of galaxy and planet formation. Observational studies of molecular clouds, the sites of star formation, primarly use molecular line emission, providing dynamical and chemical information. Two of the key parameters of astrochemical models are far-ultraviolet (FUV) flux and the cosmic ray ionization rate. We use analytic accretion histories to predict the bolometric and FUV luminosities of protostar clusters and compare different histories with observed bolometric luminosities. We find that the Tapered Turbulent Core model best represents the observed luminosities and their dispersion. We extend the models to calculate …