Limb-darkening measurements for a cool red giant in microlensing event OGLE 2004-BLG-482
| Autor: | Zub, M., Cassan, A., Heyrovsky, D., Fouque, P., Stempels, H. C., Albrow, M. D., Beaulieu, J. -P., Brillant, S., Christie, G. W., Kains, N., Kozlowski, S., Kubas, D., Wambsganss, J., Batista, V., Bennett, D. P., Cook, K., Coutures, C., Dieters, S., Dominik, M., Prester, D. Dominis, Donatowicz, J., Greenhill, J., Horne, K., Jorgensen, U. G., Kane, S. R., Marquette, J. -B., Martin, R., Menzies, J., Pollard, K. R., Sahu, K. C., Vinter, C., Williams, A., Gould, A., DePoy, D. L., Gal-Yam, A., Gaudi, B. S., Han, C., Lipkin, Y., Maoz, D., Ofek, E. O., Park, B. -G., Pogge, R. W., McCormick, J., Udalski, A., Szymanski, M. K., Kubiak, M., Pietrzynski, G., Soszynski, I., Szewczyk, O., Wyrzykowski, L. |
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| Rok vydání: | 2009 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/200912007 |
| Popis: | Aims: We present a detailed analysis of OGLE 2004-BLG-482, a relatively high-magnification single-lens microlensing event which exhibits clear extended-source effects. These events are relatively rare, but they potentially contain unique information on the stellar atmosphere properties of their source star, as shown in this study. Methods: Our dense photometric coverage of the overall light curve and a proper microlensing modelling allow us to derive measurements of the OGLE 2004-BLG-482 source star's linear limb-darkening coefficients in three bands, including standard Johnson-Cousins I and R, as well as in a broad clear filter. In particular, we discuss in detail the problems of multi-band and multi-site modelling on the expected precision of our results. We also obtained high-resolution UVES spectra as part of a ToO programme at ESO VLT from which we derive the source star's precise fundamental parameters. Results: From the high-resolution UVES spectra, we find that OGLE 2004-BLG-482's source star is a red giant of MK type a bit later than M3, with Teff = 3667 +/- 150 K, log g = 2.1 +/- 1.0 and an assumed solar metallicity. This is confirmed by an OGLE calibrated colour-magnitude diagram. We then obtain from a detailed microlensing modelling of the light curve linear limb-darkening coefficients that we compare to model-atmosphere predictions available in the literature, and find a very good agreement for the I and R bands. In addition, we perform a similar analysis using an alternative description of limb darkening based on a principal component analysis of ATLAS limb-darkening profiles, and also find a very good agreement between measurements and model predictions. Comment: Accepted in A&A |
| Databáze: | arXiv |
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