Volume 439, Number 2, August IV 2005
|Page(s)||645 - 650|
|Section||Stellar structure and evolution|
|Published online||29 July 2005|
Determination of stellar shape in microlensing event MOA 2002-BLG-33
Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, UK e-mail: firstname.lastname@example.org
2 Solar Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601, Japan
3 Department of Physics, Notre Dame University, Notre Dame, IN 46556, USA
4 Institute of Information and Mathematical Sciences, Massey University, Auckland, New Zealand
5 Department of Physics, University of the Free State, Bloemfontein, South Africa
6 Instituto de Astrofísica de Andalucía, CSIC, Apartado 3004, 18080 Granada, Spain
7 Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, CA 94563, USA
8 Hubble Fellow, Caltech Astronomy, MS 105-24, California Institute of Technology, 1200 E. California Bl., Pasadena, California
9 CEA, DSM, DAPNIA, Centre d'Études de Saclay, 91191 Gif-sur-Yvette Cedex, France
10 Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
11 Universität Hamburg, Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
12 School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
13 Laboratoire de l'Accélérateur Lineaire, IN2P3 CNRS, Université de Paris-Sud, 91405 Orsay Cedex, France
14 Faculty of Science, University of Auckland, Private Bag 92019, Auckland, New Zealand
15 School of Chemical and Physical Sciences, Victoria University, PO Box 600, Wellington, New Zealand
16 Department of Astrophysical Sciences, Princeton University, Princeton NJ 08544, USA
17 Department of Astronomy, Ohio State University, Columbus OH 43210, USA
Accepted: 2 May 2005
We report a measurement of the shape of the source star in microlensing event MOA 2002-BLG-33. The lens for this event was a close binary whose centre-of-mass passed almost directly in front of the source star. At this time, the source star was closely bounded on all sides by a caustic of the lens. This allowed the oblateness of the source star to be constrained. We found that where a and b are its semi-major and semi-minor axes respectively. The angular resolution of this measurement is approximately 0.04 . We also report HST images of the event that confirm a previous identification of the source star as an F8-G2 turn-off main-sequence star.
Key words: gravitational lensing / stars: atmospheres / stars: rotation
© ESO, 2005
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