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Author: Benjamin F. Lane
Publisher: Universal-Publishers
ISBN: 1581122004
Category : Science
Languages : en
Pages : 169
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Book Description
This dissertation describes work performed at the Palomar Testbed Interferometer (PTI) during 1998-2002. Using PTI, we developed a method to measure stellar angular diameters in the 1-3 milli-arcsecond range with a precision of better than 5%. Such diameter measurements were used to measure the mass-radius relations of several lower main sequence stars and hence verify model predictions for these stars. In addition, by measuring the changes in Cepheid angular diameters during the pulsational cycle and applying a Baade-Wesselink analysis we are able to derive the distances to two galactic Cepheids (h Aql & z Gem) with a precision of 10%; such distance determinations provide an independent calibration of the Cepheid period-luminosity relations that underpin current estimates of cosmic distance scales. Second, we used PTI and the adaptive optics facility at the Keck Telescope on Mauna Kea to resolve the low mass binary systems BY Dra and GJ 569B, resulting in dynamical mass determinations for these systems. GJ 569B most likely contains at least one sub-stellar component, and as such represents the first dynamical mass determination of a brown dwarf. Finally, a new observing technique, dual star phase referencing, was developed and demonstrated at PTI. Phase referencing allows interferometric observations of stars previously too faint to observe, and is a prerequisite for large-scale interferometric astrometry programs such as the one planned for the Keck Interferometer; interferometric astrometry is a promising technique for the study of extra-solar planetary systems, particularly ones with long-period planets.
Author: Benjamin F. Lane
Publisher: Universal-Publishers
ISBN: 1581122004
Category : Science
Languages : en
Pages : 169
Get Book Here
Book Description
This dissertation describes work performed at the Palomar Testbed Interferometer (PTI) during 1998-2002. Using PTI, we developed a method to measure stellar angular diameters in the 1-3 milli-arcsecond range with a precision of better than 5%. Such diameter measurements were used to measure the mass-radius relations of several lower main sequence stars and hence verify model predictions for these stars. In addition, by measuring the changes in Cepheid angular diameters during the pulsational cycle and applying a Baade-Wesselink analysis we are able to derive the distances to two galactic Cepheids (h Aql & z Gem) with a precision of 10%; such distance determinations provide an independent calibration of the Cepheid period-luminosity relations that underpin current estimates of cosmic distance scales. Second, we used PTI and the adaptive optics facility at the Keck Telescope on Mauna Kea to resolve the low mass binary systems BY Dra and GJ 569B, resulting in dynamical mass determinations for these systems. GJ 569B most likely contains at least one sub-stellar component, and as such represents the first dynamical mass determination of a brown dwarf. Finally, a new observing technique, dual star phase referencing, was developed and demonstrated at PTI. Phase referencing allows interferometric observations of stars previously too faint to observe, and is a prerequisite for large-scale interferometric astrometry programs such as the one planned for the Keck Interferometer; interferometric astrometry is a promising technique for the study of extra-solar planetary systems, particularly ones with long-period planets.
Author: Hans Ulrich Käufl
Publisher: Springer Science & Business Media
ISBN: 9783540252566
Category : Science
Languages : en
Pages : 588
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Book Description
Two specialized new instruments for ESO's VLT, VISIR and CRIRES, spawned the idea for this workshop. CRIRES is a dedicated very high resolution infrared spectrograph; VISIR features a high resolution spectroscopic mode. Together, the instruments combine the sensitivity of an 8m-telescope with the now well-established reliability of VLT-facility instruments. High resolution here means that lines in cool stellar atmospheres and HII-regions can be resolved. The astrophysical topics discussed in this rather specialized workshop range from the inner solar system to active galactic nuclei. There are many possibilities for new discoveries with these instruments, but the unique capability, which becomes available through high-resolution infrared spectroscopy, is the observation of molecular rotational-vibrational transitions in many astrophysical environments. Particularly interesting and surprising in this context, many papers on modeling and laboratory spectroscopy at the workshop appear to indicate that astronomical observations are lagging a bit behind in this field. The papers are an interesting mix of reports from existing high resolution facilities, reports on modeling efforts of synthetic spectra and reports on laboratory spectra. In this sense, a fruitful exchange between molecular physics and astronomy was again accomplished and is documented in this volume.
Author:
Publisher:
ISBN:
Category : Astronautics
Languages : en
Pages : 490
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Book Description
Author: Raymond Y. Chiao
Publisher: Springer Science & Business Media
ISBN: 1461223784
Category : Science
Languages : en
Pages : 675
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Book Description
This Festschrift is a collection of essays contributed by students, colleagues, and ad mirers to honor an eminent scholar on a special anniversary: Charles Hard Townes on the occasion of his 80th birthday, July 28, 1995. In 1964, Townes shared the Nobel Prize in physics with Alexander Mikhailovich Prokhorov and Nikolai Gen nadyevich Basov "for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle. " His contributions have covered a much wider area, however. His fruitful interests spanning several decades have included many scientific subjects, includ ing, microwave spectroscopy and astrophysics (other articles in this volume will expand further on this point). He has also contributed to public service, having served as the chairman of the Science and Technology Advisory Committee for NASA's Apollo program, and as a member and vice chairman of the President's Science Advisory Committee. As the enormous breadth of contributions from his students shows, he has educated scholars who are now in a wide range of fields. The contributions from his many admirers, among whom are nine fellow Nobel laureates, attest to his impact on many disciplines ranging from electrical engi neering to medicine. His influence extends even to theology, as is indicated by one essay. The broadly international character of this Festschrift reflects his deep belief in the international, universal nature of science.
Author: Andrea Richichi
Publisher: Springer Science & Business Media
ISBN: 3540742565
Category : Science
Languages : en
Pages : 583
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Book Description
Celebrating the completion of the first phase of VLTI development, the ESO workshop The Power of Optical/IR Interferometry, held in 2005, gathered researchers together to review and discuss not just interferometers, but also how science uses interferometers and their impact on astronomy as a whole. This volume contains the proceedings of this workshop, serving as a reference for astronomers working with optical and infrared interferometry.
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ISBN:
Category : Aeronautics
Languages : en
Pages : 488
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
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.
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ISBN:
Category : Aeronautics
Languages : en
Pages : 1232
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Book Description
Author: P. DELACHE (Ed)
Publisher: Atlantica Séguier Frontières
ISBN: 9782863320617
Category : Astrophysics
Languages : en
Pages : 364
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Book Description
Author: A. Richard Thompson
Publisher: Springer
ISBN: 331944431X
Category : Science
Languages : en
Pages : 910
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Book Description
This book is open access under a CC BY-NC 4.0 license. The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics. With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferometer. From this foundation, it delves into the underlying relationships of interferometry, sets forth the coordinate systems and parameters to describe synthesis imaging, and examines configurations of antennas for multielement synthesis arrays. Various aspects of the design and response of receiving systems are discussed, as well as the special requirements of very-long-baseline interferometry (VLBI), image reconstruction, and recent developments in image enhancement techniques and astrometric observations. Also discussed are propagation effects in the media between the source and the observer, and radio interference, factors that limit performance. Related techniques are introduced, including intensity interferometry, optical interferometry, lunar occultations, tracking of satellites in Earth orbit, interferometry for remote Earth sensing, and holographic measurements of antenna surfaces. This book will benefit anyone who is interested in radio interferometry techniques for astronomy, astrometry, geodesy, or electrical engineering.
