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Limb-darkening measurements for a cool red giant in microlensing event OGLE 2004-BLG-482


Zub, M and Cassan, A and Heyrovsky, D and Fouque, P and Stempels, HC and Albrow, MD and Beaulieu, JP and Brillant, S and Christie, GW and Kains, N and Kozlowski, S and Kubas, D and Wambsganss, J and Batista, V and Bennett, DP and Cook, K and Coutures, C and Dieters, S and Dominik, M and Prester, DD and Donatowicz, J and Greenhill, J and Horne, K and Jorgensen, UG and Kane, SR and Marquette, JB and Martin, R and Menzies, J and Pollard, KR and Sahu, KC and Vinter, C and Williams, A and Gould, A and DePoy, DL and Gal-Yam, A and Gaudi, BS and Han, C and Lipkin, Y and Maoz, D and Ofek, EO and Park, BG and Pogge, RW and McCormick, J and Udalski, A and Szymanski, MK and Kubiak, M and Pietrzynski, G and Soszynski, I and Szewczyk, O and Wyrzykowski, L, Limb-darkening measurements for a cool red giant in microlensing event OGLE 2004-BLG-482, Astronomy and Astrophysics, 525, (January) Article A15. ISSN 0004-6361 (2011) [Refereed Article]

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Copyright Statement

Copyright © EDP Sciences, 2010

Official URL:

DOI: doi:10.1051/0004-6361/200912007


Aims. We present a detailed analysis of OGLE 2004-BLG-482, a relatively high-magnification single-lens microlensing event that 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-482source 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.

Item Details

Item Type:Refereed Article
Keywords:gravitational lensing: micro – stars: atmospheres – techniques: high angular resolution – stars: individual: OGLE 2004-BLG-482
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Greenhill, J (Dr John Greenhill)
ID Code:68611
Year Published:2011
Web of Science® Times Cited:30
Deposited By:Mathematics and Physics
Deposited On:2011-03-15
Last Modified:2013-01-18

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