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A Survey of Radial Velocities in the Zodiacal Dust Cloud
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Название: A Survey of Radial Velocities in the Zodiacal Dust Cloud Автор: Brian May, Год: 2008 Издательство: Springer Формат: PDF ISBN: 0387777059 Размер: 111 Mb Страниц: 237 Язык: Английский The
Zodiacal Light, that misty diffuse cone of light seen in the West after
Sunset and the East before Sunrise, is a beautiful and intriguing
phenomenon. Even though everyone can enjoy the sight from a suitably
dark location, it is poorly understood, and has been the subject of
relatively little research. Brian May began his research into the
subject in 1970, and was finally awarded his PhD in 2007, after a hiatus
of more than 30 years pursuing his other career as guitarist with his
rock band Queen. This book is Brian’s thesis, and as such presents the
results of his research for astronomers. This thesis documents the
building of a pressure-scanned Fabry-Perot Spectrometer, equipped with a
photomultiplier and pulse-counting electronics, and its deployment at
the Observatorio del Teide at Izaña in Tenerife, at an altitude of 7,700
feet (2,567 m), to record high-resolution spectra of the Zodiacal
Light. The aim was to achieve the first systematic mapping of the
Magnesium I (MgI) absorption line in the night sky. More than 250 scans
of both morning and evening Zodiacal Light were obtained, in two
observing periods in 1971 and 1972. The scans showed profiles modified
by various Doppler-shifted components with respect to the unshifted
shape seen in daylight. The set of spectra obtained is compared with
predictions made from a number of different models of a dust cloud,
assuming various distributions of dust density as a function of position
and particle size, and differing assumptions about their speed and
direction. The observations fit predominantly prograde models fairly
well, but show a morning-evening asymmetry, different in the two
observing periods. Models are investigated containing various
components, including prograde and retrograde orbiting dust around the
Sun, a drift of interstellar material though the Solar System, and light
from distant emitting matter. The implications for possible asymmetries
of the Zodiacal Cloud are discussed. Other researches on the Zodiacal
Dust Cloud are reviewed, including recent insights into its structure,
orientation, and evolution. Brian’s observations are evaluated in this
context. BrianMay
