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Author: Janice Christine Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 400
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Book Description
An outstanding question in galaxy evolution research is whether the star formation histories of low mass systems are dominated by global starbursts or modes that are more quiescent and continuous. In this thesis, we quantify the prevalence of global starbursts in dwarf galaxies at the present epoch, and attempt to infer their characteristic durations, frequencies and amplitudes in the past. Our approach is to directly tally the number of bursting dwarfs in a complete local sample, and to compute the fraction of star formation that is concentrated in these systems. The resulting starburst number and mass fractions are then combined with B-V colors from the literature, the H-alpha EWs presented here, and stellar evolutionary synthesis models in order to place constraints on the average starburst duty cycle. The primary dataset used has been put together by the 11 Mpc H-alpha UV Galaxy Survey, who have collected data on an approximately volume-limited, statistical sample of star-forming galaxies within 11 Mpc of the Milky Way. Our main observational results, along with the accumulation of star formation studies of dwarf galaxies over the past three decades, paint a consistent picture where systems that are currently experiencing a massive global burst are just the 6% +/- 3% tip of a low-mass galaxy iceberg. Moreover, bursts are responsible for 22% +/- 10% of the total star formation in the overall dwarf galaxy population, so the majority of stars in low-mass systems do not appear to be formed in this mode today. Over their lifetimes, however, a greater fraction of the stellar mass of a dwarf may be formed in the burst mode. Synthesis modeling suggests that bursts cycles appear to be necessary in order to simultaneously explain the present-day observed blue B-V colors and modest H-alpha EWs of TYPICAL, CURRENTLY NON-BURSTING dwarf irregulars, unlessnon-standard assumptions concerning the IMF and the escape fractions of Lyman continuum photons are made. The starburst cycle that we converge upon involves burst durations of 50-100 Myrs, cycle frequencies of 1 to 3 per Gyr, and elevated burst SFRs that are a factor of 6-10 higher than the rate in the quiescent state. Galaxies characterized by such a SFH would spend 1̃0% of their lives in the burst state, and form 5̃0% of their stellar mass during this time.
Author: Janice Christine Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 400
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Book Description
An outstanding question in galaxy evolution research is whether the star formation histories of low mass systems are dominated by global starbursts or modes that are more quiescent and continuous. In this thesis, we quantify the prevalence of global starbursts in dwarf galaxies at the present epoch, and attempt to infer their characteristic durations, frequencies and amplitudes in the past. Our approach is to directly tally the number of bursting dwarfs in a complete local sample, and to compute the fraction of star formation that is concentrated in these systems. The resulting starburst number and mass fractions are then combined with B-V colors from the literature, the H-alpha EWs presented here, and stellar evolutionary synthesis models in order to place constraints on the average starburst duty cycle. The primary dataset used has been put together by the 11 Mpc H-alpha UV Galaxy Survey, who have collected data on an approximately volume-limited, statistical sample of star-forming galaxies within 11 Mpc of the Milky Way. Our main observational results, along with the accumulation of star formation studies of dwarf galaxies over the past three decades, paint a consistent picture where systems that are currently experiencing a massive global burst are just the 6% +/- 3% tip of a low-mass galaxy iceberg. Moreover, bursts are responsible for 22% +/- 10% of the total star formation in the overall dwarf galaxy population, so the majority of stars in low-mass systems do not appear to be formed in this mode today. Over their lifetimes, however, a greater fraction of the stellar mass of a dwarf may be formed in the burst mode. Synthesis modeling suggests that bursts cycles appear to be necessary in order to simultaneously explain the present-day observed blue B-V colors and modest H-alpha EWs of TYPICAL, CURRENTLY NON-BURSTING dwarf irregulars, unlessnon-standard assumptions concerning the IMF and the escape fractions of Lyman continuum photons are made. The starburst cycle that we converge upon involves burst durations of 50-100 Myrs, cycle frequencies of 1 to 3 per Gyr, and elevated burst SFRs that are a factor of 6-10 higher than the rate in the quiescent state. Galaxies characterized by such a SFH would spend 1̃0% of their lives in the burst state, and form 5̃0% of their stellar mass during this time.
Author: John Michael Cannon
Publisher:
ISBN:
Category :
Languages : en
Pages : 448
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Publisher: Cuvillier Verlag
ISBN: 3736909594
Category : Science
Languages : de
Pages : 186
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Book Description
Author: Xuan Thuan Trinh
Publisher: Atlantica Séguier Frontières
ISBN: 9782863320501
Category : Galaxies
Languages : en
Pages : 626
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Book Description
Author: Polychronis Papaderos
Publisher: Springer Science & Business Media
ISBN: 3642220185
Category : Science
Languages : en
Pages : 347
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Book Description
Dwarf galaxy research constitutes an extremely vibrant field of astrophysical research, with many long-standing questions still unsettled and new ones constantly arising. The intriguing diversity of the dwarf galaxy population, observed with advanced ground-based and space-borne observatories over a wide spectral window providing an unprecedented level of detail, poses new challenges for both observers and theoreticians. The aim of this symposium was to bring together these two groups to exchange ideas and new results on the many evolutionary aspects of and open issues concerning dwarf galaxies. The main topics addressed include: the birth of dwarf galaxies: theoretical concepts and observable relics across wavelengths and time, the morphological, structural and chemical evolution of dwarf galaxies, possible evolutionary connections between early-type and late-type dwarfs, the star formation history of dwarf galaxies and its dependence on intrinsic and environmental properties, the origin and implications of starburst activity in dwarf galaxies, the fate of dwarfish systems born out of tidally ejected matter in galaxy collisions.
Author: L. Tacconi
Publisher: Springer Science & Business Media
ISBN: 3642565387
Category : Science
Languages : en
Pages : 349
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Book Description
A major fraction of star formation in the universe occurs in starbursts. These regions of particularly rapid star formation are often located towards the centers of host galaxies. Studies of this kind of star formation at high redshift have produced astonishing results over recent years that were only possible with the latest generation of large ground-based and space telescopes. The papers collected in this volume present these results in the context of the much firmer foundation of star formation in the local universe, and they emphasize all the important topics, from star formation in different environments to the cosmic star formation history.
Author: Susanne Hüttemeister
Publisher: American Institute of Physics
ISBN:
Category : Science
Languages : en
Pages : 452
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Book Description
Starbursts are a spectacular phase in the life of galaxies, with the potential of changing the appearance of the galaxy and enriching its environment with metals in galactic winds. They are a sign post of galaxy evolution and galaxy assembly at high redshifts. This volume brings together all aspects of starburst evolution, focusing on the much debated question of what triggers starbursts.
Author: Richard de Grijs
Publisher: Springer Science & Business Media
ISBN: 140203539X
Category : Science
Languages : en
Pages : 390
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Book Description
Starbursts are important features of early galaxy evolution. Many of the distant, high-redshift galaxies we are able to detect are in a starbursting phase, often apparently provoked by a violent gravitational interaction with another galaxy. In fact, if we did not know that major starbursts existed, these conference proceedings testify that we would indeed have difficulties explaining the key properties of the Universe! These conference proceedings cover starbursts from the small-scale star-forming regions in nearby galaxies to galaxy-wide events at high redshifts; one of the major themes of the conference proved to be "scalability", i.e., can we scale up the small-scale events to describe the physics on larger scales. The key outcome of this meeting – and these proceedings – is a resounding "yes" to this fundamental, yet profound question. The enhanced synergy facilitated by the collaboration among observers using cutting-edge ground and space-based facilities, theorists and modellers has made these proceedings a true reflection of the state of the art in this very rapidly evolving field.
Author: Claus Leitherer
Publisher: Cambridge University Press
ISBN: 9780521404655
Category : Science
Languages : en
Pages : 354
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Book Description
This book reviews the importance of massive stars in several areas of astrophysics. Massive stars are objects that are 10-100 times the mass of our Sun. Above ten solar masses, loss through stellar winds begins to have a major impact on the evolution of a star. The upper limit of 100 solar masses is derived from observations. Significant progress has now been achieved in massive star research. New models, along with high quality observations, have improved our understanding of the formation, structure, atmosphere, and evolution of these massive objects. They are formed in violent bursts of star formation and are probably related to the phenomena observed in active galactic nuclei. The workshop at the Space Telescope Science Institute examined the interplay between the astrophysics of massive stars and their location in extragalactic starburst regions. There are eighteen chapters by leading researchers. Each has been carefully edited to ensure that the book is a comprehensive introduction to the theory and observation of massive stars in starburst regions.
Author: Wu Zhongqi
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Book Description
