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Author: Willem A. Baan Publisher: Springer Science & Business Media ISBN: 1402038313 Category : Science Languages : en Pages : 312
Book Description
These proceedings summarize our present knowledge on astronomical molecules, highlight major problems to be addressed, and finally propose future work. Their theoretical understanding involves physics, numerical simulations and chemistry.
Author: Willem A. Baan Publisher: Springer Science & Business Media ISBN: 1402038313 Category : Science Languages : en Pages : 312
Book Description
These proceedings summarize our present knowledge on astronomical molecules, highlight major problems to be addressed, and finally propose future work. Their theoretical understanding involves physics, numerical simulations and chemistry.
Author: Adrian Vantyghem Publisher: ISBN: Category : Galaxies Languages : en Pages : 170
Book Description
In this thesis I use ALMA observations to map the distribution and kinematics of molecular gas in the brightest cluster galaxies of three galaxy clusters: 2A0335+096, RXJ0821+0752, and RXCJ1504-0248. The goal is to understand how the coldest gas in clusters is formed, identify any long-lived structures that could fuel sustained black hole accretion, and explore star formation in cluster environments. I use the J=1-0 and J=3-2 rotational transitions of carbon monoxide (CO) as tracers of the total molecular gas distribution. The two transitions provide different resolutions and fields of view. The molecular gas in all three central galaxies are complex and disturbed. None show evidence for rotationally-supported nuclear structures, such as a disk or ring, that would be expected from either a merger origin or long-lived cooling flow. Instead, the molecular gas is either clumpy with no clear velocity structure or extends away from the galactic center in filaments that are several kiloparsecs long. The molecular filaments are coincident with nebular and bright X-ray emission, suggesting that they have condensed out of the hot intracluster medium. They are also generally associated with cavities in the X-ray emission inflated by the active galactic nucleus (AGN), suggesting that AGN feedback has stimulated the formation of molecular gas. The narrow velocity gradients along the filaments are only consistent with freefall if the filament is situated close to the plane of the sky. This is a common feature in brightest cluster galaxies. Since ram pressure is ineffective at slowing dense molecular clouds, the filaments must either be pinned to the hot atmosphere by magnetic fields or have condensed in-situ relatively recently. In RXCJ1504-0248 I combine the ALMA analysis with spatially-resolved ultraviolet emission tracing young stars. The central gas falls on the Kennicutt-Schmidt relation, while the filament has elevated star formation surface densities. The ongoing consumption of a finite fuel supply by star formation, or spatial variations in the CO-to-H2 conversion factor, may be diminishing the molecular gas surface density to produce this effect. Despite their drastic differences in morphology and environment, the molecular gas in clusters is still converted into stars following the same relation as in spirals and starbursts. I have also detected the J=3-2 transition from 13CO, an optically thin isotopologue of 12CO, in RXJ0821.0+0752. This enables a measurement of the conversion between CO intensity and molecular column density for the first time in a galaxy cluster. The CO-to-H2 conversion factor in RXJ0821+0752 is half of the Galactic value. If this value applies to other clusters, then it would alleviate the high coupling efficiencies required for molecular filaments to be uplifted by X-ray cavities. This analysis also provides reassurance that the molecular gas masses measured in BCGs are unlikely to be overwhelmingly biased by adopting the Galactic conversion factor.
Author: J. M. T. Thompson Publisher: World Scientific ISBN: 1860945775 Category : Science Languages : en Pages : 434
Book Description
"Derived in part from work originally published in the Philosophical Transactions of the Royal Society, series A (Phil. Trans. R. Soc. A, 360, 2649-3004, 2002)."--t.p.
Author: Molly J. Gallagher Publisher: ISBN: Category : Astronomy Languages : en Pages : 181
Book Description
Gas density plays an important role in galactic evolution via its connection to star formation. Yet because dense gas is difficult to observe, we are only beginning to explore how interstellar gas density and its relationship to the star formation rate (SFR) depend on galactic environment. My thesis presents three comparisons between gas density, SFR, and galactic environment in nearby spiral galaxies.
Author: Steven W. Stahler Publisher: John Wiley & Sons ISBN: 3527618686 Category : Science Languages : en Pages : 865
Book Description
This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text for physics and astronomy graduate students, and as a reference for professional scientists.
Author: Willem A. Baan
Author: Willem A. Baan
Author: Willem A. Baan
Author: Adrian Vantyghem
Author: Andrew Jordan Baker
Author: J. M. T. Thompson
Author: Molly J. Gallagher
Author: Adam Kirby Leroy
Author: Steven W. Stahler
Author: 
Author: Yu Gao