High-Resolution Velocity Fields of Low-Mass Disk Galaxies PDF Download
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Author: Phuongmai Truong
Publisher:
ISBN:
Category :
Languages : en
Pages : 101
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Book Description
Author: Phuongmai Truong
Publisher:
ISBN:
Category :
Languages : en
Pages : 101
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Book Description
Author: Rachel Kuzio De Naray
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Jesús Falcón-Barroso
Publisher: Cambridge University Press
ISBN: 1107035279
Category : Science
Languages : en
Pages : 657
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Book Description
The formation and evolution of galaxies is one of the most important topics in modern astrophysics. Secular evolution refers to the relatively slow dynamical evolution due to internal processes induced by a galaxy's spiral arms, bars, galactic winds, black holes and dark matter haloes. It plays an important role in the evolution of spiral galaxies with major consequences for galactic bulges, the transfer of angular momentum, and the distribution of a galaxy's constituent stars, gas and dust. This internal evolution is in turn the key to understanding and testing cosmological models of galaxy formation and evolution. Based on the twenty-third Winter School of the Canary Islands Institute of Astrophysics, this volume presents reviews from nine world-renowned experts on the observational and theoretical research into secular processes, and what these processes can tell us about the structure and formation of galaxies. The volume provides a firm grounding for graduate students and early career researchers working on galactic dynamics and galaxy evolution.
Author: Ralf Bender
Publisher: Springer Science & Business Media
ISBN: 9783540002055
Category : Science
Languages : en
Pages : 394
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Book Description
Measuring the masses of galaxies as a function of redshift is perhaps one of the most challenging open issues in current astronomical research. The evolution of the baryonic and dark matter components of galaxies is not only a critical test of the hierarchical formation paradigm, but ultimately also provides new clues on the complex interplay between star formation, the cooling and heating of gas and galaxy merging processes. This book reviews current techniques to measure the baryonic (stellar) and dark masses of nearby galaxies, and focusses on ongoing attempts to measure theses same quantities in galaxies at higher and higher redshifts. It also gives room to future perspectives, with special emphasis on new survey projects and satellite missions.
Author: Eric Robert Schulman
Publisher:
ISBN:
Category : Disks (Astrophysics)
Languages : en
Pages : 450
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 159
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Book Description
One of the most important drivers of galaxy evolution is feedback from massive stars and supernovae. Some of the most direct observational signatures of this are galactic winds, multi-phase outflows of gas and dust driven from a galaxy by feedback. The physically-extended nature of winds lends itself to spatially-resolved observations. As a result, integral-field spectroscopy has become an important component in the study of galactic winds. This thesis advances both our understanding of galactic winds and our capability for observing them in a spatially-resolved manner. I first present the design and construction of two new integral-field units (IFUs) optimized for the study of extragalactic targets. HexPak and GradPak are the first fiber-fed IFUs to use different fiber diameters in their designs, sampling multiple angular scales simultaneously. The different diameters allow for more efficient observing of both face-on and spheroidal galaxies as well as edge-on disk galaxies. HexPak features a hexagonal arrangement of fibers with an inlaid circular core of high spatial-resolution fibers. GradPak uses stacked rows of fibers, with fiber diameter increasing along the stack. Both designs trade spatial resolution for increased collecting area at large scale-distances from galaxy centers where surface brightnesses are lower. I also present studies of the properties of H-alpha-emitting and UV-absorbing gas in the galactic winds of the local starburst galaxies NGC 7552 and NGC 7714. The first study, targeting NGC 7552, examines the relationship between the properties of the galactic wind measured via H-alpha emission lines and measured via ultraviolet absorption lines. In the second study, focused on the galaxy NGC 7714, I present a model of the H-alpha kinematics of its galactic wind. This model recreates distinctive features of the galaxy's velocity field and constrains the outflow velocity of the wind. These studies suggest that outflow velocities and mass outflow rates are lower than typically calculated by other H-alpha-derived methods by factors of a few. Both studies also find that the total wind mass and mass outflow rate measured in H-alpha are lower than that measured in the UV by an order of magnitude.
Author: Regina von Berlepsch
Publisher: John Wiley & Sons
ISBN: 3527643850
Category : Science
Languages : en
Pages : 231
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Book Description
This 22nd volume in the series contains 15 invited reviews and highlight contributions from outstanding speakers presented during the 2009 annual meeting of the Astronomical Society on the subject of "Deciphering the Universe through Spectroscopy", held in Potsdam, Germany. Topics range from the measurements of magnetic fields on the surface of the sun via detailed measurements of abundances in stellar atmospheres to the kinematics of the universe at its largest scales. The result is a systematic overview of the latest astronomical and cosmological research.
Author: Frank Hohl
Publisher:
ISBN:
Category : Galaxies
Languages : en
Pages : 116
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Book Description
A computer model for isolated disks of stars is presented and is used to study the self-consistent motion of large numbers of point masses as they move in the plane of the galactic disk. The Control Data 6600 computer system at the Langley Research Center was used to integrate the equations of motion for each star for systems containing from 50,000 to 200,000 stars. Any initially cold balanced disk was found to be violently unstable. A sufficient amount of velocity dispersion will stabilize all small-scale disturbances. However, most disks investigated were found to be unstable against slowly growing long-wavelength modes, and after about two rotations the disks tended to assume a bar-shaped structure. It was also found that the final mass distribution for most disks could be closely approximated by an exponential variation irrespective of the initial mass distribution. To study the development of spiral structure, the model was modified to include a fixed central force similar to that in the Schmidt model of the Galaxy. The mass of the stars in the disk was taken to be from 5 to 50 percent of the total mass of the Galaxy. The evolution of a number of initial distributions of stars was investigated. The results of the calculation gave a velocity dispersion for the disk stars which was about 50 percent larger than the value of about 30 km/sec found from observation of stars in the solar neighborhood. For some of the disks investigated, a pronounced spiral structure remained even after 8.5 rotations.
Author: Roberto J. Galván-Madrid
Publisher: Springer Science & Business Media
ISBN: 1461433088
Category : Science
Languages : en
Pages : 131
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Book Description
The most massive stars in the galaxy - those with more than 15 to 20 solar masses - are lilkely to ionize their surroundings before they reach their final mass. How can they accrete in spite of the presence of over-pressurized gas? This thesis presents results of Submillimeter Array (SMA) and Very Large Array (VLA) studies of massive star formation regions in the early stages of ionization, as well as an analysis of numerical simulations of the evolution of these young HII regions. The results favor a picture in which very massive stars form in accretion flows that are partially ionized and that keep accreting material from their environment.
Author: A.K. Dupree
Publisher: Springer Science & Business Media
ISBN: 9400930372
Category : Science
Languages : en
Pages : 463
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Book Description
This book represents the Proceedings of the NATO Advanced Study Insti tute on Formation and Evolution of Low Mass Stars held from 21 September to 2 October 1987 at Viana do Castelo, Portugal. Holding the meeting in Portugal recognized both the historical aspects and the bright future of astronomy in Portugal. In the early sixteenth century, the Portugese played an important role in the critical diffusion of classical and medieval knowledge which formed so large a part of scientific activity at that time. Navigation and course setting, brought to a high level by Portugese explorers, relied on mathematics and astronomy to produce precise tables of solar positions. In contemporary Portu gal, astronomy is the focus of renewed interest and support at the universities. It is thus particularly appropriate that the NATO Advanced Study Institute was held on the coast of the Atlantic Ocean in the friendly surroundings of the Costa Verde.
