Download or read book Shocks Superbubbles and Filaments written by Andrew Richard Pon and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Giant molecular clouds (GMCs), out of which stars form, are complex, dynamic systems, which both influence and are shaped by the process of star formation. In this dissertation, I examine three different facets of the dynamical motions within GMCs. Collapse modes in different dimensional objects.Molecular clouds contain lower dimensional substructures, such as filaments and sheets. The collapse properties of finite filaments and sheets differ from those of spherical objects as well as infinite sheets and filaments. I examine the importance of local collapse modes of small central perturbations, relative to global collapse modes, in different dimensional objects to elucidate whether strong perturbations are required for molecular clouds to fragment to form stars. I also calculate the dependence of the global collapse timescale upon the aspect ratio of sheets and filaments. I find that lower dimensional objects are more readily fragmented, and that for a constant density, lower dimensional objects and clouds with larger aspect ratios collapse more slowly. An edge-driven collapse mode also exists in sheets and filaments and is most important in elongated filaments. The failure to consider the geometry of a gas cloud is shown to lead to an overestimation of the star formation rate by up to an order of magnitude.Molecular tracers of turbulent energy dissipation.Molecular clouds contain supersonic turbulence that simulations predict will decay rapidly via shocks. I use shock models to predict which species emit the majority of the turbulent energy dissipated in shocks and find that carbon monoxide, CO, is primarily responsible for radiating away this energy. By combining these shock models with estimates for the turbulent energy dissipation rate of molecular clouds, I predict the expected shock spectra of CO from molecular clouds. I compare the results of these shock models to predictions for the emission from the unshocked gas in GMCs and show that mid-to-high rotational transitions of CO (e.g., J = 8 to 7), should be dominated by shocked gas emission and should trace the turbulent energy being dissipated in molecular clouds.Orion-Eridanus superbubble.The nearby Orion star forming region has created a large bubble of hot plasma in the local interstellar medium referred to as the Orion-Eridanus superbubble. This bubble is unusual in that it is highly elongated, is believed to be oriented roughly parallel to the galactic plane, and contains bright filamentary features on the Eridanus side. I fit models for a wind driven bubble in an exponential atmosphere to the Orion-Eridanus superbubble and show that the elongation of the bubble cannot be explained by such a model in which the scale height of the galactic disk is the typical value of 150 pc. Either a much smaller scale height must be adopted or some additional physics must be added to the model. I also show that the Eridanus filaments cannot be equilibrium objects ionized by the Orion star forming region.
Download or read book Terrestrial and Extraterrestrial Space Dangers Outer Space Perils Rocket Risks and the Health Consequences of the Space Environment written by Dirk C. Gibson and published by Bentham Science Publishers. This book was released on 2015-02-24 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural elements and cosmic phenomena in space, such as asteroids, comets, meteors, black holes and super bubbles pose a threat to the planet Earth and spacefarers in the near-Earth environment. Terrestrial and Extraterrestrial Space Dangers describes these dangers in the near-Earth outer space environment. The uniquely risky nature of rocket transportation is documented and quantified. The human health consequences for vision, muscles, and the neurovestibular system, for instance, on exposure to an outer space environment, are also explained in this book. Readers will benefit from the extensive information offered within this text which is also accompanied with a bibliography of references. This book offers a comprehensive primer for anyone interested in space travel and associated risk assessment.
Download or read book Cosmic Magnetic Fields written by Richard Wielebinski and published by Springer Science & Business Media. This book was released on 2005-09-13 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: While magnetic fields permeate the universe on all scales, the present book is dedicated to their investigation on the largest scales and affords a balanced account of both theoretical and observational aspects. Written as a set of advanced lectures and tutorial reviews that lead up to the forefront of research, this book offers both a modern source of reference for the experienced researchers as well as a high-level introductory text for postgraduate students and nonspecialist researchers working in related areas.
Download or read book Protostars and Planets VI written by Henrik Beuther and published by University of Arizona Press. This book was released on 2014-12-18 with total page 945 pages. Available in PDF, EPUB and Kindle. Book excerpt: The revolutionary discovery of thousands of confirmed and candidate planets beyond the solar system brings forth the most fundamental question: How do planets and their host stars form and evolve? Protostars and Planets VI brings together more than 250 contributing authors at the forefront of their field, conveying the latest results in this research area and establishing a new foundation for advancing our understanding of stellar and planetary formation. Continuing the tradition of the Protostars and Planets series, this latest volume uniquely integrates the cross-disciplinary aspects of this broad field. Covering an extremely wide range of scales, from the formation of large clouds in our Milky Way galaxy down to small chondrules in our solar system, Protostars and Planets VI takes an encompassing view with the goal of not only highlighting what we know but, most importantly, emphasizing the frontiers of what we do not know. As a vehicle for propelling forward new discoveries on stars, planets, and their origins, this latest volume in the Space Science Series is an indispensable resource for both current scientists and new students in astronomy, astrophysics, planetary science, and the study of meteorites.
Download or read book The Interplay Between Massive Star Formation the ISM and Galaxy Evolution written by D. Kunth and published by Atlantica Séguier Frontières. This book was released on 1996 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of X ray and Gamma ray Astrophysics written by Cosimo Bambi and published by Springer Nature. This book was released on with total page 5912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Galactic and Extragalactic Background Radiation written by International Astronomical Union. Symposium and published by Springer Science & Business Media. This book was released on 1990-08-31 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 139th Symposium of the International Astronomical Union on `The Galactic and Extragalactic Background Radiation, held in Heidelberg, FRG, June 12-16, 1989
Download or read book From the Realm of the Nebulae to Populations of Galaxies written by Mauro D'Onofrio and published by Springer. This book was released on 2016-07-26 with total page 809 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to outline possible future directions in galaxy research, this book wants to be a short stopover, a moment of self-reflection of the past century of achievements in this area. Since the pioneering years of galaxy research in the early 20th century, the research on galaxies has seen a relentless advance directly connected to the parallel exponential growth of new technologies. Through a series of interviews with distinguished astronomers the editors provide a snapshot of the achievements obtained in understanding galaxies. While many initial questions about their nature have been addressed, many are still open and require new efforts to achieve a solution. The discussions may reveal paradigms worthwhile revisiting. With the help of some of those scientists who have contributed to it, the editors sketch the history of this scientific journey and ask them for inspirations for future directions of galaxy research.
Download or read book ESO Workshop on Low Mass Star Formation and Pre main Sequence Objects written by Bo Reipurth and published by . This book was released on 1989 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring the X Ray Universe written by Philip A. Charles and published by CUP Archive. This book was released on 1995-10-12 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: The one-stop general book on the whole of X-ray astronomy.
Download or read book How does the Galaxy work written by Emilio Javier Alfaro and published by Springer Science & Business Media. This book was released on 2006-03-30 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: TheinternationalconferenceHowdoestheGalaxywork? Agalactictertulia rd th with Don Cox and Ron Reynolds, was held during the week of 23 to 27 of June 2003 in the marvelous city of Granada, Spain. This week marked the beginningofoneofthehottestsummersthatwehaveeverlived, butincontrast, the meeting was one of the coolest events that we can remember! First, it certainly wasa?rstclassscienti?creunion, withanexcellent program, talented speakers, and alive discussions in a friendly atmosphere. Second, the whole event was embedded in the passionate Andalucian way of life, a true tertulia, well seasoned with tasty tapas and perfectly marinated in cool and dry sherry wine. Third, the celebration was framed by some of the most beautiful settings thatonecanimagine; weenjoyedthemagni?centsplendoroftheAlhambra,the unique Muslim-Jewish-Christian ?avor of the Albaicin, and the magical gipsy heartbeat of Sacromonte. Last but not least, all discussions, whether they were duringthesessionsoratabartable,weresprinkledwiththecharmandwitofthe twoguestsofhonor: DonCoxandRonReynolds. Theideaofhavingascienti?c feast to celebrate their 60th birthday in Granada was actually conceived at a bar table in Seville, with plenty of manzanilla at hand, a couple of summers ago. That, perhaps, was the dif?cult part of the project. The rest was relatively easy to achieve because Don and Ron are not only remarkable astronomers but they are also great human beings. Indeed, we had a very positive response from all parties involved: every person we talked to was enthusiastic about the celebration, and wanted to give their own point of view in this tertulia.
Download or read book Physics of Thermal Gaseous Nebulae written by L.H. Aller and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gaseous nebulae offer outstanding opportunities to atomic physicists, spectroscopists, plasma experts, and to observers and theoreticians alike for the study of attenuated ionized gases. These nebulae are often dusty, heated by radiation fields and by shocks. They are short-lived phenomena on the scale of a stellar lifetime, but their chemical compositions and internal kinematics may give important clues to advanced stages of stellar evolution. The material herein presented is based on lectures given at the University of Michigan, University of Queensland, University of California, Los Angeles, and in more abbreviated form at the Raman Institute, at the Scuola Internazionale di Trieste, and elsewhere. Much of it is derived origionally from the series "Physical Processes in Gaseous Nebulae" initiated at the Harvard College Observatory in the late 1930s. I have tried to emphasize the basic physics of the mechanisms involved and mention some of the uncertainties that underlie calculations of many basic parameters. Emphasis is placed on ionized plasmas with electron temperatures typically in the neighborhood of 10,OOOoK. Dust and other ingredients of the cold component of the interstellar medium are treated briefly from the point of view of their relation to hot plasmas of H II regions and planetaries. Chemical composition determinations for nebulae are discussed in some detail while the last section deals with interpretations of elemental abundances in the framework of stellar evolution and nucleogenesis. Gaseous nebulae offer some particularly engaging opportunities for studies of stellar evolution.
Download or read book The Evolution of Galaxies and Their Environment written by David J. Hollenbach and published by . This book was released on 1993 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Symposium written by International Astronomical Union and published by . This book was released on 1992 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gamma ray and Neutrino Signatures of Galactic Cosmic ray Accelerators written by Silvia Celli and published by Springer Nature. This book was released on 2019-12-17 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses three “hot” topics concerning the general problem of the origin of Galactic cosmic rays, namely (1) the acceleration, propagation, and radiation of particles in supernova remnants; (2) very high energy neutrinos from the Galactic Center; and (3) the potential held by the next-generation gamma-ray and neutrino detectors CTA and KM3NeT for studying extended non-thermal sources in the Galaxy. The topics are intrinsically connected to determining the nature (“hadronic or leptonic?”) of gamma-ray emissions from young and middle-aged supernova remnants and the search for cosmic-ray PeVatrons. The results and conclusions provided here are based on extensive analytical and numerical simulations, which are formulated and presented in a straightforward format that can be readily used in the interpretations of gamma-ray and neutrino observations, as well as for confident predictions for future measurements.
Download or read book The Heliosphere in the Local Interstellar Medium written by Rudolf von Steiger and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: In summary, we can conclude that the contributions of the different ionization processes to the total ionization rate for the most abundant interstellar species are basically known. The ionization of the noble gases He and Ne is almost completely dominated by photoionization, whereas for H charge-exchange with the solar wind is most important. For other species, such as 0 and Ar, both processes contribute significantly. Electron impact ionization can typically contribute by '" 10% to the total rate in the inner Solar System. Because direct measurements of the solar EUV flux are not yet continuously available, the variation of the ionization rate over the solar cycle still contains a relatively large uncertainty. The recent measurements of pickup ion distributions and of the neutral helium gas provide an independent tool to determine the total ionization rate that can be used to cross calibrate with the results obtained for the individual ionization processes. Acknowledgements The authors are grateful to M. Allen for supplying us with new data on photoioniza tion cross-sections compiled by him. We thank also M. Gruntman for drawing our attention to and support in collecting the most recent data on charge-exchange cross-sections. D. R. was supported by grant No. 2 P03C. 004. 09 from the Com mittee for Scientific Research (Poland). This work was also supported in part through NASA contract NAS7-918, NSF Grant INT-911637, NASA Grant NAGW- 2579.
Download or read book Literature 1991 Part 2 written by Astronomisches Rechen-Institut and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Astronomy and Astrophysics Abstracts" appearing twice a year has become oneof the fundamental publications in the fields of astronomy, astrophysics andneighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. The abstrats are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world.
