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One solar cycle of solar astrometry with MDI/SOHO

Published online by Cambridge University Press:  26 February 2010

Marcelo Emilio ,
Jeff R. Kuhn  and
Rock I. Bush
Marcelo Emilio
Affiliation:
Observatório Astronômico-Departamento de Geociências Universidade Estadual de Ponta Grossa, Paraná, Brazil email: memilio@uepg.br
Jeff R. Kuhn
Affiliation:
Institute for Astronomy, University of Hawaii, Woodlawn Dr. 96822, HI, USA email: kuhn@ifa.hawaii.edu
Rock I. Bush
Affiliation:
Solar Physics Group, Stanford University, Stanford, CA, 94305, USA email: rbush@solar.stanford.edu
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Abstract

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In this work we describe the method and results of precise solar astrometry made with the Michelson Doppler Imager (MDI), on board the Solar and Heliospheric Observatory (SOHO), during one complete solar cycle. We measured an upper limit to the solar radius variation, the absolute solar radius value and the solar shape. Our results are 22 mas peak-to-peak upper limit for the solar radius variation over the solar cycle, the absolute radius was measured as 959.28 ± 0.15 arcsec at 1 AU and the difference between polar and equatorial solar radii in 1997 was 5 km and about three times larger in 2001.

Keywords

Sun: fundamental parameters(Sun:) solar-terrestrial relationsSun: oscillationsSun: photosphere

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