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PLANET Observations of Microlensing Event OGLE-1999-BUL-23: Limb-darkening Measurement of the Source Star

Citation

Albrow, MD and An, J and Beaulieu, JP and Caldwell, JAR and DePoy, DL and Dominik, M and Gaudi, BS and Gould, A and Greenhill, JG and Hill, KM and Kane, S and Martin, R and Menzies, J and Pogge, RW and Pollard, KR and Sackett, PD and Sahu, KC and Vermaak, P and Watson, RD and Williams, A, PLANET Observations of Microlensing Event OGLE-1999-BUL-23: Limb-darkening Measurement of the Source Star, The Astrophysical Journal, 549, (2) pp. 759-769. ISSN 0004-637X (2001) [Refereed Article]

DOI: doi:10.1086/319437

Abstract

We present PLANET observations of OGLE-1999-BUL-23, a binary-lens microlensing event toward the Galactic bulge. PLANET observations in the I and V bands cover the event from just before the first caustic crossing until the end of the event. In particular, a densely sampled second caustic crossing enables us to derive the linear limb-darkening coefficients of the source star: c v = 0.786 +0.080 -0.078 and c I = 0.632 +0.047 -0.037. Combined analysis of the light curve and the color-magnitude diagram suggests that the source star is a G/K subgiant in the Galactic bulge (T eff ≃ 4800 K). The resulting linear limb-darkening coefficient of the source is consistent with theoretical predictions, although it is likely that nonlinearity of the stellar surface brightness profile complicates the interpretation, especially for the I band. The global light curve fit to the data indicates that the event is due to a binary lens of a mass ratio q ≃ 0.39 and a projected separation d ≃ 2.42. The lens/source relative proper motion is (22.8 ± 1.5) km s -1 kpc -1, typical of bulge/bulge or bulge/disk events.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Greenhill, JG (Dr John Greenhill)
Author:Hill, KM (Dr Kym Hill)
Author:Kane, S (Dr Stephen Kane)
Author:Watson, RD (Dr Bob Watson)
ID Code:22112
Year Published:2001
Web of Science® Times Cited:61
Deposited By:Physics
Deposited On:2001-08-01
Last Modified:2002-05-09
Downloads:0

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