Download or read book Dynamical Evolution of Dust in Expanding Circumstellar Shells written by Carl Covatto and published by . This book was released on 2002 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics and Chemistry of Circumstellar Dust Shells written by Hans-Peter Gail and published by Cambridge University Press. This book was released on 2014 with total page 699 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores why dust forms around stars, and how to model stellar dust formation and dust-forming environments consistently.
Download or read book Extremely Extended Dust Shells Around Evolved Intermediate Mass Stars written by Basil Menzi Mchunu and published by . This book was released on 2011 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intermediate mass stars ( %0 .8 - 8 solar masses), at the asymptotic giant branch phase (AGB) suffer intensive mass loss, which leads to the formation of a circumstellar shell (s) of gas and dust in their circumstellar envelope. At the end of the AGB phase, the mass-loss decreases or stops and the circumstellar envelope begins to drift away from the star. If the velocity of the AGB phase wind has been relatively constant, then dust or molecular emission furthest from the star represents the oldest mass loss, while material closer to the star represents more recent mass loss. Therefore, the history of mass loss during the AGB phase is imprinted on the dust shells of the post-AGB envelope. Thus, by studying the distribution of material in the form of dust emission in the circumstellar shells of late evolved stars (i.e. the post AGB phases are pre - planetary nebula (PPN) and the planetary nebula (PN)) we can gain a better understanding of the mass-loss processes involved in the evolution of intermediate mass stars. I studied two groups of intermediate mass stars, namely six oxygen rich and six carbon rich candidates. In this thesis a study of evolution of intermediate mass stars is confronted by means of observations, in which far - infrared (FIR) images, are used to study the physical properties and the material distribution of dust shells of AGB and post AGB circumstellar envelope. Infrared radiation from thermal dust emission can be used to probe the entire dust shell because, near to mid-infrared radiation arises solely from the hottest regions close to the star; while the outer regions away from the star are cool such that they emit at longer infrared wavelengths. Essentially, radiation in the FIR to sub-millimeter wavelengths is emitted by the entire dust shell and hence can be used to probe the entire dusty envelope. Therefore far-infrared emission by late evolved stars can be used to probe the large scale - structure of AGB and post - AGB circumstellar shells.Our results from space observations indicated the following: The sizes of the circumstellar dust shell observed in oxygen rich stars are within %1 pc. We derived the dust masses derived from far infrared ISO PHT 32 observation of oxygen rich stars that are between 1.7 -- 4 x 10-4 solar masses. These results provides us with a lower limit in the progenitor masses of stars estimated to be within 0.56 -- 0.76 solar masses. These results indicate that the initial main sequence masses fro oxygen rich stars are within 1 - 3.5 solar masses. The time scales derived since the oldest mass was ejected during the evolution of oxygen rich stars are 4 - 13 x 104 years. For the carbon rich stars: The size of the circumstellar dust shells are within 1 - 1.6 pc. The masses of dust in the shells are a approximated to be within 0.1 - 1.44 x 10-4 solar masses. A lower limit to the progenitor masses of carbon rich stars that are between 0.61 - 0.9 solar mass, suggesting that these stars evolved from the main sequence masses between 2. - 6 solar masses.
Download or read book Hydrodynamics and Dust Formation in the Circumstellar Shells of Miras and Long Period Variables written by Axel J. Fleischer and published by . This book was released on 1994 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrodynamics and Dust Formation in the Circumstellar Shells of Miras and Long Period Variables written by Axel J. Fleischer and published by . This book was released on 1994 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Circumstellar Media in Late Stages of Stellar Evolution written by Robin E. S. Clegg and published by Cambridge University Press. This book was released on 1994-08-25 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last throes of their lives, how do low- and high-mass stars interact with their immediate surroundings? How does the circumstellar medium affect the shape of a nebula? How are supernovae effected by a dense medium? And what do we understand of how stellar winds interact with their environments? These and many other exciting issues are addressed in these proceedings, from the 34th Herstmonceux conference, held in Cambridge. Highlights of developments in the field covered in this volume include the latest observational results that show how various types of stellar ejecta differ in shape, and a unified view of the physical processes involved; as well as the latest results on the media around supernovae 1987A and 1993J. This timely volume provides review articles that serve both as an excellent introduction for graduate students, and a handy reference for researchers; and up-to-date research papers for those who want to keep abreast of developments in the field.
Download or read book Literature 1981 Part 2 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 803 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structure of Circumstellar Shells written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-04 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document provides a report on research activities carried out with the support of NASA grant NAG 5-1174, the Structure of Circumstellar Shells, funded under the Astrophysics Data Program. The research carried out with the support of this grant is a study of the properties of circumstellar dust shells for which spectra are available through IRAS low resolution spectrometry (LRS). This research consisted of the development and application of models of axisymmetric circumstellar shells and a preliminary survey of the applicability of neural nets for analysis of the IRAS LRS spectra of circumstellar dust shells. Fix, John D. NASA-CR-192337, NAS 1.26:192337 NAG5-1174...
Download or read book The Origin and Evolution of Dust in Interstellar and Circumstellar Environments written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: This status report covers the period from the commencement of the research program on 1 Jul. 1992 through 30 Apr. 1993. Progress is reported for research in the following areas: (1) grain formation in circumstellar envelopes; (2) photochemistry in circumstellar envelopes; (3) modeling ice features in circumstellar envelopes; (4) episodic dust formation in circumstellar envelopes; (5) grain evolution in the diffuse interstellar medium; and (6) grain evolution in dense molecular clouds. Whittet, Douglas C. B. and Leung, Chun M. Unspecified Center...
Download or read book The Biggest Baddest Coolest Stars written by Donald Gerard Luttermoser and published by . This book was released on 2009 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cool evolved stars are among the brightest point sources in the infrared sky, and contribute significantly to the interstellar dust of galaxies. They are in a short-lived but important stage of stellar evolution, characterized by pulsations, dust formation, and the production of expanding circumstellar shells. This conference highlighted the physics of evolved cool stars in relation to their stage of evolution, atmospheric structure and dynamics, stellar winds, and associated dust formation. The conference was held at the Millennium Centre near the campus of East Tennessee State University in Johnson City, Tennessee, in July 2007. It brought together astronomers, both professional and amateur, who are working on different aspects of cool star research. These included dust theorists, numerical modelers, and experts in observations at different wavelengths. The result of the meeting was a more complete picture of these stars, which is summarized in this volume. Several recent developments motivated the need for this conference. Current hydrodynamic models of evolved stars are now able to reproduce the optical/UV spectra of such stars. However, simultaneous modeling of the infrared spectrum has proven difficult. Also, adding dust to such modeling is problematic because of the complicated physics of dust formation, destruction, and emission in these dynamic environments. Furthermore, the exact evolutionary relationship between the various types of cool evolved stars still is uncertain. The perceptive reader will discover a number of provocative research directions embedded in the many fine contributions herein.
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2001 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Evolution of Dust in the Terrestrial Planet Region of Circumstellar Disks Around Young Stars written by Diane Dutkevitch and published by . This book was released on 1995 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book From Miras to Planetary Nebulae written by M. O. Mennessier and published by Atlantica Séguier Frontières. This book was released on 1990 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Literature 1992 Part 1 written by Astronomisches Recheninstitut and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1456 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 abstracts 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.
Download or read book The Dynamics of Circumstellar Shells written by Mark G. Mulhern and published by . This book was released on 1991 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Supernovae written by Athem W. Alsabti and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:
