Discovery of Very-Low-Mass Binary Stars and Circumstellar Disks in the Infrared PDF Download
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Author: Nick Siegler
Publisher:
ISBN:
Category :
Languages : en
Pages : 440
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Book Description
We present results from three infrared observational studies investigating different aspects of stellar evolution. The first survey, conducted in the near-infrared with adaptive optics, measures for the first time the stellar multiplicity properties of field M6-M7.5 dwarf stars. We report that their binary fraction, separation distribution, and mass ratio distribution are very similar to those of later spectral type stars and brown dwarfs while distinct from more massive stellar binaries. These differences, when coupled with age, shed light on possibly different formation mechanisms and kinematic evolution between binary systems of different primary masses. I incorporate these results with those from all known very-low mass binary systems and present their statistical properties. We also present the discovery of a very tight (66 mas) brown dwarf companion to a mid-L dwarf demonstrating the capabilities of laser guide star adaptive optics. In the second study we present mid-infrared Spitzer observations of members of the ~ 50 Myr open stellar cluster IC 2391 where, using photometric techniques, we report that about a third of the solar-like stars (spectral types FGK) likely possess debris disks. With respect to several other stellar groups of known age, we show for the first time the evolution of the debris disk fraction of solar-like stars. We conclude that, along with more massive late-B and A stars, the formation of planetesimals around solar-like stars appears to be a universal process of star formation. Lastly, we present preliminary near- and mid-infrared Spitzer observations of stars in the direction of the ~ 6 Myr open cluster IC 2395. Using photometric techniques, we identify upper main sequence cluster members and lower-mass candidate members with evidence of circumstellar disks at different stages of disk evolution - primordial, transition, and debris. We present for the first time the evolution of the median IRAC flux ratios emitted from the inner 0.2 AU regions of classic T Tauri stars. These results are possibly consistent with the processes of grain growth and dust settling as a mechanism for planetesimal formation.
Author: Nick Siegler
Publisher:
ISBN:
Category :
Languages : en
Pages : 440
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Book Description
We present results from three infrared observational studies investigating different aspects of stellar evolution. The first survey, conducted in the near-infrared with adaptive optics, measures for the first time the stellar multiplicity properties of field M6-M7.5 dwarf stars. We report that their binary fraction, separation distribution, and mass ratio distribution are very similar to those of later spectral type stars and brown dwarfs while distinct from more massive stellar binaries. These differences, when coupled with age, shed light on possibly different formation mechanisms and kinematic evolution between binary systems of different primary masses. I incorporate these results with those from all known very-low mass binary systems and present their statistical properties. We also present the discovery of a very tight (66 mas) brown dwarf companion to a mid-L dwarf demonstrating the capabilities of laser guide star adaptive optics. In the second study we present mid-infrared Spitzer observations of members of the ~ 50 Myr open stellar cluster IC 2391 where, using photometric techniques, we report that about a third of the solar-like stars (spectral types FGK) likely possess debris disks. With respect to several other stellar groups of known age, we show for the first time the evolution of the debris disk fraction of solar-like stars. We conclude that, along with more massive late-B and A stars, the formation of planetesimals around solar-like stars appears to be a universal process of star formation. Lastly, we present preliminary near- and mid-infrared Spitzer observations of stars in the direction of the ~ 6 Myr open cluster IC 2395. Using photometric techniques, we identify upper main sequence cluster members and lower-mass candidate members with evidence of circumstellar disks at different stages of disk evolution - primordial, transition, and debris. We present for the first time the evolution of the median IRAC flux ratios emitted from the inner 0.2 AU regions of classic T Tauri stars. These results are possibly consistent with the processes of grain growth and dust settling as a mechanism for planetesimal formation.
Author: International Astronomical Union. Symposium
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 656
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Author: William J. Caplan
Publisher:
ISBN:
Category :
Languages : en
Pages : 84
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Author: Anatoliĭ Mikhaĭlovich Cherepashchuk
Publisher: Taylor & Francis
ISBN: 9789056990121
Category : Science
Languages : en
Pages : 366
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Book Description
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309157994
Category : Science
Languages : en
Pages : 324
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Book Description
Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
Author: Henrik Beuther
Publisher: University of Arizona Press
ISBN: 0816531242
Category : Science
Languages : en
Pages : 945
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Book Description
Proceedings of a conference held in Heidelberg, Germany, July 15-20, 2013.
Author: C. Eiroa
Publisher: Springer Science & Business Media
ISBN: 9401154686
Category : Science
Languages : en
Pages : 333
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Book Description
The past year has produced some of the most exciting results in the history of astronomy, particularly in the area of planets outside our solar system. Only a half-year before our meeting in Toledo, Spain, the first unambiguous detection of planet-sized masses orbiting main sequence stars were reported. Since that time, evidence for a new exo planet has been reported almost at the rate of about once per month. Some of these objects are likely to turn out to be very low-mass stars, but something like half show characteristics - Jupiter-like mass and near-zero orbital eccentricity - which appear to be unique to planets. Almost at the same time that giant planets were being discovered regularly, the two major space agencies, ESA and NASA, have iden tified searches for and detailed study of Earth-like planets as a major priority for the future. In ESA's "Horizon 2000 Plus" programme, an infrared interferometer has been proposed as a possible future Cor nerstone mission. Similarly, scientists in the US produced the "Road Map for the Exploration of Neighboring Planetary Systems (ExNPS)", which provided NASA with a long-term plan which leads also to an infrared interferometer in space to study hypothetical Earth-like worlds beyond our Solar System. Such an observatory is designed to search for the thermal emission from a family of planets, using interferometric nulling to remove the contaminating light from the central star.
Author: Vincent Mannings
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1470
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Book Description
Click here for the online version of this book! This title, out of print in 2008, is now available free of charge, in it's entirety, online through the University of Arizona Press! Both a textbook and a status report for every facet of research into the formation of stars and planets, Protostars and Planets IV brings together 167 authors who report on the most significant advances in the field since the publication of the previous volume in 1993. Protostars and Planets IV reflects improvements in observational techniques and the availability of new facilities such as the Infrared Space Observatory, the refurbished Hubble Space Telescope, and the 10-m Keck telescopes. Advances in computer technology and modeling methods have benefited theoretical studies of molecular clouds, star formation, and jets and disks, while recent analyses of meteorites yield important insights into conditions and processes within our Sun's early protoplanetary disk. The 49 chapters describe context and progress for observational and theoretical studies of the structure, chemistry, and dynamics of molecular clouds; the collapse of cores and the formation of protostars; the formation and properties of young binary stars; the properties of winds, jets, and molecular outflows from young stellar objects; the evolution of circumstellar envelopes and disks; grain growth in disks and the formation of planets; and the properties of the early Solar nebula. Protostars and Planets IV is also the first book to include chapters describing the discoveries of extrasolar planets, brown dwarfs, and Edgeworth-Kuiper Belt objects, and the first to include high-resolution optical and near-infrared images of protoplanetary disks. Protostars and Planets IV is an unsurpassed reference not only for established researchers but also for younger scientists whose imagination and work will lead to tomorrow's discoveries.
Author: Lee Hartmann
Publisher: Cambridge University Press
ISBN: 9780521785204
Category : Science
Languages : en
Pages : 260
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Book Description
This first comprehensive account of the dynamical processes in the formation of stars and disks from which planets ultimately form.
Author: F. Palla
Publisher: Springer Science & Business Media
ISBN: 3540316337
Category : Science
Languages : en
Pages : 242
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Book Description
The book begins with a historical introduction, "Star Formation: The Early History", that presents new material of interest for students and historians of science. This is followed by two long articles on "Pre-Main-Sequence Evolution of Stars and Young Clusters" and "Observations of Young Stellar Objects". These articles on the fascinating problem of star formation from interstellar matter give a thorough overview of present-day theories and observations. The articles contain material so far unpublished in the astronomical literature. The book addresses graduate students and can be used as a textbook for advanced courses in stellar astrophysics.
