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Issue A&A
Volume 388, Number 1, June II 2002
Page(s) L1 - L4
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20020507



A&A 388, L1-L4 (2002)
DOI: 10.1051/0004-6361:20020507

Letter

Gravitational microlensing as a test of stellar model atmospheres

H. M. Bryce1, 2, M. A. Hendry1 and D. Valls-Gabaud3

1  Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
2  203 Van Allen Hall, Department of Physics and Astronomy, University of Iowa, Iowa City, IA, 52242, USA
3  CNRS UMR 5572, Observatoire Midi-Pyrénées, 14 avenue E. Belin, 31400 Toulouse, France

(Received 12 December 2001 / Accepted 2 April 2002)

Abstract
We present calculations illustrating the potential of gravitational microlensing to discriminate between classical models of stellar surface brightness profiles and the recently computed "Next Generation" models of Hauschildt et al. These spherically-symmetric models include a much improved treatment of molecular lines in the outer atmospheres of cool giants - stars which are very typical sources in Galactic bulge microlensing events. We show that the microlensing signatures of intensively monitored point and fold caustic crossing events are readily able to distinguish between NextGen and the classical models, provided a photometric accuracy of 0.01 mag is reached. This accuracy is now routinely achieved by alert networks, and hence current observations can discriminate between such model atmospheres, providing a unique insight on stellar photospheres.


Key words: gravitational lensing: stars -- stars: atmospheres, fundamental parameters, imaging

Offprint request: martin@astro.gla.ac.uk




© ESO 2002


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