1112.5878 (Costantino Sigismondi)
Costantino Sigismondi
The measurement of the solar diameter is introduced in the wider framework of
solar variability, and, consequently of the influences of the Sun upon the
Earth's climate. It is possible to measure the solar diameter with enough
accuracy to study climate changes and irradiation variations using ancient
eclipses. This would permit to extend the knowledge of the solar luminosity
back to three centuries, through the parameter W=dLogL/dLog R. The method of
eclipses and Baily beads is discussed, and a significant improvement with
respect to the last 40 years, has been obtained by reconstructing the Limb
Darkening Function from the Baily's bead light curve, and the search of its
inflexion point. The case of the Jan 15, 2010 annular eclipse has been studied
in detail, while the atlas of Baily's beads with worldwide contributions by
IOTA members, along with the solar diameter during the eclipse of 2006, have
been published. The transition between the photographic atlas of the lunar limb
(Watts, 1963) and the laser-altimeter map made by the Kaguya lunar probe and
published in November 2009 has been followed. The other method for the accurate
measurement of the solar diameter alternative to the Picard / Picard-sol
mission is the drift-scan method used either by the solar astrolabes either by
larger telescopes. The observatories of Locarno and Paris have started an
observational program of the Sun with this method with encouraging results. For
the first time an image motion of the whole Sun has been detected over
frequencies of 1/100 Hz. This may start explain the puzzling results of the
observational campaigns made in Greenwich and Rome from 1850 to 1955. A giant
pinhole telescope as the meridian line of Santa Maria degli Angeli in Rome,
permits to introduce almost all the arguments of classical astrometry presented
in this thesis. In this consists the final didactic outreach.
View original:
http://arxiv.org/abs/1112.5878
No comments:
Post a Comment