Advanced Evolution Of Massive Stars .4. Secondary Nucleosynthesis During Helium Burning

NSF GP-32051, GP-23282Astronom

Rapid neutron capture in supernova explosions

Rapid neutron capture in supernova explosion

Massive Stars in the Range 13−25M⊙\rm 13-25 M_\odot: Evolution and Nucleosynthesis. II. the Solar Metallicity Models

We present the evolutionary properties of a set of massive stellar models (namely 13, 15, 20 and 25 $\rm M_\odot$) from the main sequence phase up to the onset of the iron core collapse. All these models have initial solar chemical composition, i.e. Y=0.285 and Z=0.02. A 179 isotope network, extending from neutron up to $\rm ^{68}Zn$ and fully coupled to the evolutionary code has been adopted from the Carbon burning onward. Our results are compared, whenever possible, to similar computations available in literature.Comment: 42 pages, 18 figures, 26 tables, accepted for publicatin in ApJ

The natural resources of Bolinas Lagoon: their status and future

This publication is an integral part of the Department's high-priority inventory and assessment of coastal marshland and tideflat resources. It is intended as a guide for citizens, planners, administrators, and all others interested in the use and development of coastal lands and waters. Although the resources and problems of Bolinas Lagoon have probably been the subject of more biological and physical investigations than any small estuarine area of the California coast, many of the pertinent reports and information are not readily available to the public. Consequently, it is one purpose of this report to summarize the lagoon's history, ecological attractions, educational values and the problems facing its continued existence. At the same time, it should provide concerned citizens with a knowledge of the sources of additional and more specific information. Publication of this report is consistent with the obligation of the Department of Fish and Game to do everything in its power to protect and maintain the State's fish and wildlife resources. Therefore, its purpose transcends local issues on pollution and development, and the Department is, in fact, submitting a report to the people on the status and future of part of its inheritance and the dowry of coming generations. The report is the third of a scheduled series. It follows similar releases on Upper Newport Bay (Orange County) and Goleta Slough (Santa Barbara county) in March and June of 1970. Documentation of the resources of other critical areas is in progress. There will be future reports of this nature on Elkhorn Slough, Morro Bay, Tomales Bay, Humboldt Bay, and highly threatened marshlands in southern California. (137 pp.

Computing and data processing

The applications of computers and data processing to astronomy are discussed. Among the topics covered are the emerging national information infrastructure, workstations and supercomputers, supertelescopes, digital astronomy, astrophysics in a numerical laboratory, community software, archiving of ground-based observations, dynamical simulations of complex systems, plasma astrophysics, and the remote control of fourth dimension supercomputers

The natural resources of Humboldt Bay

In spite of its past abuses by man, Humboldt Bay is one of the few coastal estuaries remaining in California that has not been rendered largely unsuitable for wildlife by commercial development, dredging, filling or pollution. Its importance is emphasized considering that about 65 percent of the State's original estuarine tidelands have already been destroyed. The people have demonstrated their concern for our dwindling natural resources. If we are to preserve what remains it will be necessary for the people to exercise the wisest possible use of these resources. Because of the importance of coastal wetlands to the fish and wildlife of California, the Department of Fish and Game has initiated a high priority statewide inventory of these wetlands. This publication is an integral part of that program. It is intended as a guide for citizens, planners, administrators and all others interested in the use and development of coastal lands and waters. The Department has been charged with the responsibility of protecting and maintaining the fish and wildlife resources of the State. This publication is directed towards meeting this responsibility by outlining the specific resources and recreational aspects of Humboldt Bay, elucidating problems, and recommending courses of action for future development. Preservation of the Humboldt Bay resources is much more than a local issue. What is done or not done here can have statewide, national and international implications. It also must be recognized that there is an obligation to future generations. Decisions made today will affect all those who follow in our footsteps. (200pp.

Presupernova Structure of Massive Stars

Issues concerning the structure and evolution of core collapse progenitor stars are discussed with an emphasis on interior evolution. We describe a program designed to investigate the transport and mixing processes associated with stellar turbulence, arguably the greatest source of uncertainty in progenitor structure, besides mass loss, at the time of core collapse. An effort to use precision observations of stellar parameters to constrain theoretical modeling is also described.Comment: Proceedings for invited talk at High Energy Density Laboratory Astrophysics conference, Caltech, March 2010. Special issue of Astrophysics and Space Science, submitted for peer review: 7 pages, 3 figure

Inclusive Masculinity and Facebook Photographs Among Early Emerging Adults at a British University

Central to debates about the construction of masculinity in sociology is the influence of culture and what constitutes acceptable displays of masculinity. This article adopts a novel approach in examining this question. It adopts a summative content analysis, combined with a semiotic analysis, of 1,100 Facebook photographs, in order to explore the underlying meanings within the photos and the performances of masculinity. Facebook photographs from 44, straight, White, male, early emerging adults attending the same university are used as a representation of an individual’s ideal self. These are then analyzed in order to determine the behaviors endorsed by peer culture. It was found that the sample overwhelmingly adopted inclusive behaviors (including homosocial tactility, dancing, and kissing each other), and inclusive masculinity theory was utilized to contextualize participants’ constructions of masculinity. Thus, this research shows that emerging adult males at this university construct their masculine identities away from previous orthodox archetypes. It is argued that the reducing importance of gendered behavior patterns may represent an adoption of what are perceived as wider cultural norms and act as a symbol of adulthood to these early emerging adults

The natural resources of Elkhorn Slough: their present and future use

This report summarizes the history of the slough, ecological attractions, educational value, and problems facing its continued existence. Appended references provide the interested and concerned citizen with sources of more specific information. As a result of the initial survey of estuarine areas of California (California Department of Fish and Game, 1969), the critical status of the coastal marshes became obvious. This report on Elkhorn Slough is part of the high priority inventory and assessment of coastal wetlands by the Department of Fish and Game, and it is intended as a guide for citizens, planners, administrators, and all others interested in the use and development of coastal lands and waters. As such, this report transcends local issues on pollution and development and, in fact, documents the status and future of natural resources that should be a part of the inheritance of following generations. This publication is one of a scheduled series. It follows similar documents on Upper Newport Bay (orange county), Goleta Slough (Santa Barbara County) and the Bolinas Lagoon (Marin county). (Document has 126 pages

Bondi Accretion and the Problem of the Missing Isolated Neutron Stars

A large number of neutron stars (NSs), ~10^9, populate the Galaxy, but only a tiny fraction of them is observable during the short radio pulsar lifetime. The majority of these isolated NSs, too cold to be detectable by their own thermal emission, should be visible in X-rays as a result of accretion from the interstellar medium. The ROSAT all sky survey has however shown that such accreting isolated NSs are very elusive: only a few tentative candidates have been identified, contrary to theoretical predictions that up to several thousands should be seen. We suggest that the fundamental reason for this discrepancy lies in the use of the standard Bondi formula to estimate the accretion rates. We compute the expected source counts using updated estimates of the pulsar velocity distribution, realistic hydrogen atmosphere spectra, and a modified expression for the Bondi accretion rate as suggested by recent MHD simulations, and supported by direct observations in the case of accretion around supermassive black holes in nearby galaxies and in our own. We find that, whereas the inclusion of atmospheric spectra partly compensates for the reduction in the counts due to the higher mean velocities of the new distribution, the modified Bondi formula dramatically suppresses the source counts. The new predictions are consistent with a null detection at the ROSAT sensitivity.Comment: accepted to ApJ; 19 pages, 4 figure