Determination of stellar shape in microlensing event MOA 2002-BLG-33
/ Authors
N. Rattenbury, F. Abe, D. Bennett, I. Bond, J. Calitz, A. Claret, K. Cook, Y. Furuta, A. Gal-yam, J. Glicenstein
and 23 more authors
J. Hearnshaw, P. Hauschildt, P. Kilmartin, Y. Kurata, K. Masuda, D. Maoz, Y. Matsubara, P. Meintjes, M. Moniez, Y. Muraki, S. Noda, E. Ofek, K. Okajima, L. Philpott, S. Rhie, T. Sako, D. Sullivan, T. Sumi, D. Terndrup, P. Tristram, J. Wood, T. Yanagisawa, P. Yock
/ Abstract
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 a/b = 1.02 +0.04 -0.02 where a and b are its semi-major and semi-minor axes respectively. The angular resolution of this measurement is approximately 0.04 μarcsec. 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.
Journal: Astronomy and Astrophysics