Molecular Clouds as Probes of Milky Way Structure and Interstellar Turbulence PDF Download
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Author: Julia Duval
Publisher:
ISBN:
Category :
Languages : en
Pages : 536
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Book Description
Abstract: The Galactic Ring Survey, a 13 CO survey of the first quadrant of the Milky Way, is used to probe the spiral structure of the Galaxy and to constrain the formation and turbulent structure of molecular clouds. A sample of 829 molecular clouds has been identified in the Galactic Ring Survey (GRS). Kinematic distances to 750 of these GRS clouds are derived. The Galactic surface mass density of molecular gas is subsequently computed from 13 CO and 12 CO emission detected in the GRS and the University of Massachusetts-Stony Brook surveys. The Galactic distribution of molecular clouds is strongly enhanced along the Scutum-Crux, Sagittarius, and Perseus arms. These molecular data are consistent with a four-arm model of the Galaxy, while the locations of the Scutum-Crux and Perseus arms are consistent with the distribution of the old stellar population inferred from infrared maps. Physical properties of molecular clouds such as size, mass, and density, are also derived in order to compare clouds located inside and outside spiral arms, and to constrain formation models. Molecular clouds located inside inferred spiral arms are found to be more massive, to have higher surface mass densities, and to be more strongly gravitationally bound than inter-arm clouds. This supports cloud formation models involving spiral structure and suggests that molecular clouds must have lifetimes of a few million years. The turbulent structure of molecular clouds is a fundamental component of star formation. The GRS is the first large scale, fully sampled 13 CO survey of the Galaxy allowing the observation of the sub-parsec-scale structure of molecular clouds. Principal Component Analysis applied to both GRS clouds and numerical simulations allows the derivation of turbulent energy spectra over scales ranging from 0.1 pc to 50 pc. The slope of the energy spectrum, E(k), versus the wavenumber, k, obtained for the GRS clouds is consistent with compressible, intermittent turbulence. The slopes and amplitudes of the energy spectra of the clouds are fairly constant over three decades of masses, which indicates that turbulence is driven on large scales by an external, Galactic pool of kinetic energy.
Author: Julia Duval
Publisher:
ISBN:
Category :
Languages : en
Pages : 536
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Book Description
Abstract: The Galactic Ring Survey, a 13 CO survey of the first quadrant of the Milky Way, is used to probe the spiral structure of the Galaxy and to constrain the formation and turbulent structure of molecular clouds. A sample of 829 molecular clouds has been identified in the Galactic Ring Survey (GRS). Kinematic distances to 750 of these GRS clouds are derived. The Galactic surface mass density of molecular gas is subsequently computed from 13 CO and 12 CO emission detected in the GRS and the University of Massachusetts-Stony Brook surveys. The Galactic distribution of molecular clouds is strongly enhanced along the Scutum-Crux, Sagittarius, and Perseus arms. These molecular data are consistent with a four-arm model of the Galaxy, while the locations of the Scutum-Crux and Perseus arms are consistent with the distribution of the old stellar population inferred from infrared maps. Physical properties of molecular clouds such as size, mass, and density, are also derived in order to compare clouds located inside and outside spiral arms, and to constrain formation models. Molecular clouds located inside inferred spiral arms are found to be more massive, to have higher surface mass densities, and to be more strongly gravitationally bound than inter-arm clouds. This supports cloud formation models involving spiral structure and suggests that molecular clouds must have lifetimes of a few million years. The turbulent structure of molecular clouds is a fundamental component of star formation. The GRS is the first large scale, fully sampled 13 CO survey of the Galaxy allowing the observation of the sub-parsec-scale structure of molecular clouds. Principal Component Analysis applied to both GRS clouds and numerical simulations allows the derivation of turbulent energy spectra over scales ranging from 0.1 pc to 50 pc. The slope of the energy spectrum, E(k), versus the wavenumber, k, obtained for the GRS clouds is consistent with compressible, intermittent turbulence. The slopes and amplitudes of the energy spectra of the clouds are fairly constant over three decades of masses, which indicates that turbulence is driven on large scales by an external, Galactic pool of kinetic energy.
Author: Ralph E. Pudritz
Publisher: Springer Science & Business Media
ISBN: 9400929730
Category : Science
Languages : en
Pages : 652
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Book Description
Recent advances in the instrumentation used to observe star forming regions in both our own Milky Way and in external galaxies have transformed the subject from a phenomenological pursuit into an increasingly unified, physical science. High resolution centimetre, millimetre, infrared, and optical studies of local star forming clouds have allowed us to probe the physics of star formation down to spatial scales approaching those of the solar system. These developments make it possible to better constrain the basic physical processes underlying star formation itself. At the same time, these new instruments have placed extragalactic studies on a footing detailed enough to allow comparison with star forming regions within our own galaxy. This revolution means that we will soon be able to link the physics of local star forming regions to the global star forming properties of galaxies. The entire structure of this NATO Advanced Study Institute was designed to explore this new view of the subject. This Institute on "Galactic and Extragalactic Star Formation" was held from June 21 -July 4, 1987 at the Conference Centre in the village of Whistler, British Columbia, Canada. The informal atmosphere of this lovely mountain resort stim ulated many valuable scientific exchanges. The Institute was funded by a major grant from NATO Scientific Affairs. Additional financial and I.I1oral assistance was provided by the Canadian Institute for Theoretical Astrophysics (CITA) and Mc Master University.
Author: Ole Marggraf
Publisher:
ISBN:
Category :
Languages : en
Pages : 119
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Book Description
Author: W.F. Wall
Publisher: Springer
ISBN:
Category : Medical
Languages : en
Pages : 492
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Book Description
This book is unique in containing comprehensive, tutorial articles by recognized experts on almost every aspect of millimeter-wavelength astronomy. These include scientific reviews of topics ranging from the solar system, to studies of the milky way and other galaxies, and finally cosmological studies. Articles on molecular structure and using molecules to probe the dense interstellar medium and star formation give a good overview of these important areas of research. A variety of critical astrophysical topics including molecule formation, shocks, magnetic fields, turbulence, and energetics of the dense interstellar medium are covered. In addition to theory and observation, the volume includes very useful articles on experimental techniques, including antennas, receivers, and spectrometers.
Author: James Lequeux
Publisher: Springer Science & Business Media
ISBN: 3540266933
Category : Science
Languages : en
Pages : 444
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Book Description
Describing interstellar matter in our galaxy in all of its various forms, this book also considers the physical and chemical processes that are occurring within this matter. The first seven chapters present the various components making up the interstellar matter and detail the ways that we are able to study them. The following seven chapters are devoted to the physical, chemical and dynamical processes that control the behaviour of interstellar matter. These include the instabilities and cloud collapse processes that lead to the formation of stars. The last chapter summarizes the transformations that can occur between the different phases of the interstellar medium. Emphasizing methods over results, The Interstellar Medium is written for graduate students, for young astronomers, and also for any researchers who have developed an interest in the interstellar medium.
Author: Edvige Corbelli
Publisher: Springer Science & Business Media
ISBN: 1402034075
Category : Science
Languages : en
Pages : 551
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Book Description
Theideatocelebrate50yearsoftheSalpeterIMFoccurredduringtherecent IAU General Assembly in Sydney, Australia. Indeed, it was from Australia that in July 1954 Ed Salpeter submitted his famous paper "The Luminosity Function and Stellar Evolution" with the rst derivation of the empirical stellar IMF. This contribution was to become one of the most famous astrophysics papers of the last 50 years. Here, Ed Salpeter introduced the terms "original mass function" and "original luminosity function", and estimated the pro- bility for the creation of stars of given mass at a particular time, now known as the "Salpeter Initial Mass Function", or IMF. The paper was written at the Australian National University in Canberra on leave of absence from Cornell University (USA) and was published in 1955 as 7 page note in the Astroph- ical Journal Vol. 121, page 161. To celabrate the 50th anniversary of the IMF, along with Ed Salpeter’s 80th birthday, we have organized a special meeting that brought together scientists involved in the empirical determination of this fundamental quantity in a va- ety of astrophysical contexts and other scientists fascinated by the deep imp- cations of the IMF on star formation theories, on the physical conditions of the gas before and after star formation, and on galactic evolution and cosmology. The meeting took place in one of the most beautiful spots of the Tuscan countryside, far from the noise and haste of everyday life.
Author: Akio Makishima
Publisher: Elsevier
ISBN: 0128120592
Category : Science
Languages : en
Pages : 270
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Book Description
Origins of the Earth, Moon, and Life: An Interdisciplinary Approach presents state-of-the-art knowledge that is based on theories, experiments, observations, calculations, and analytical data from five astro-sciences, astronomy, astrobiology, astrogeology, astrophysics, and cosmochemistry. Beginning with the origin of elements, and moving on to cover the formation of the early Solar System, the giant impact model of the Earth and Moon, the oldest records of life, and the possibility of life on other planets in the Solar System, this interdisciplinary reference provides a complex understanding of the planets and the formation of life. Synthesizing concepts from all branches of astro-sciences into one, the book is a valuable reference for researchers in astrogeology, astrophysics, cosmochemistry, astrobiology, astronomy, and other space science fields, helping users better understand the intersection of these sciences. Includes extensive figures and tables to enhance key concepts Uses callout boxes throughout to provide context and deeper explanations Presents up-to-date information on the universe, stars, planets, moons, and life in the solar system Combines knowledge from the fields of astrogeology, astrophysics, cosmochemistry, astrobiology, and astronomy, helping readers understand the origins of the Earth, the moon, and life in our solar system
Author: W.B. Burton
Publisher: Springer Science & Business Media
ISBN: 3540316299
Category : Science
Languages : en
Pages : 409
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Book Description
The previous Saas-Fee Advanced Course dedicated to the interstellar medium took place in 1972. The tremendous scientific advances that have occurred in this field since then, in particular owing to the availabihty of receivers working at completely unexplored wavelength bands, fuUy justified a new set of lectures. As a consequence, the members of the Swiss Society for Astrophysics and As tronomy voted that "The Galactic Interstellar Medium" should be the subject of the 1991 course. The 21st Saas Fee Advanced Course took place in Les Diablerets from 18 to 23 March 1991, gathering together about 80 participants from all over the world, but mostly from Europe. According to a rule that has proved to lead to success, but also to chal lenge the lecturers' energy, the format of a Saas-Fee Advanced Course consists traditionally of 28 lectures of 45 minutes which take place in the morning and late afternoon, leaving ample time for discussions, self-study, hiking or skiing. Despite the inordinate work load imposed, this year's lecturers felt that the subject was sufficiently dense to increase the lecture time by 1/3! This proved judicious and left more time for questions and discussions during the lectures.
Author: José Franco
Publisher: Cambridge University Press
ISBN: 9780521651318
Category : Science
Languages : en
Pages : 304
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Book Description
This timely volume presents a series of review articles covering every aspect of interstellar turbulence--from accretion disks, molecular clouds, atomic and ionized media, through to spiral galaxies - based on a major international conference held in Mexico City.With advances in observational techniques and the development of more efficient computer codes and faster computers, research in this area has made spectacular progress in recent years. This book provides a comprehensive overview of the most important developments in observing and modelling turbulent flows in the cosmos. It provides graduate student and researchers with a state-of-the-art summary of observational, theoretical and computational research in interstellar turbulence.
Author: David Andrew Grabelsky
Publisher:
ISBN:
Category : Carbon monoxide
Languages : en
Pages : 362
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Book Description
