Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations

¹ PLANET collaboration member
² Universität Potsdam, Astrophysik, Am Neuen Palais 10, 14469 Potsdam, Germany e-mail: kubas@astro.physik.uni-potsdam.de
³ Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
⁴ DSM/DAPNIA, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
⁵ University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews, KY16 9SS, UK
⁶ University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch, New Zealand
⁷ European Southern Observatory, Casilla 19001, Vitacura 19, Santiago, Chile
⁸ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁹ Technical University of Vienna, Dept. of Computing, Wiedner Hauptstrasse 10, Vienna, Austria
¹⁰ Observatoire Midi-Pyrénées, 14 avenue Édouard Belin, 31400 Toulouse, France
¹¹ Niels Bohr Institute, Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
¹² University of Tasmania, Physics Department, GPO 252C, Hobart, Tasmania 7001, Australia
¹³ South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
¹⁴ Astronomisches Rechen-Institut, Mönchhofstrasse 12-14, 69120 Heidelberg, Germany
¹⁵ Perth Observatory, Walnut Road, Bickley, Perth 6076, Australia
¹⁶ RSAA, Mount Stromlo and Siding Spring Observatories, ANU, Cotter Road, Weston Creek, Canberra, ACT 2611, Australia

Received: 29 December 2004
Accepted: 27 January 2005

Abstract

We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge-Disc lens scenario with a lens mass of and distance of , the wide binary lens solution requires a rather implausible binary black-hole lens (). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations.