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OGLE 2008-BLG-290: an accurate measurement of the limb darkening of a galactic bulge K Giant spatially resolved by microlensing


Fouque, P and Heyrovsky, D and Dong, S and Gould, A and Udalski, A and Albrow, MD and Batista, V and Beaulieu, JP and Bennett, DP and Bond, IA and Bramich, DM and Calchi Novati, S and Cassan, A and Coutures, C and Dieters, S and Dominik, M and Prester, DD and Greenhill, J and Horne, K and Jorgensen, UG and Kozlowski, S and Kubas, D and Lee, CH and Marquette, JB and Mathiasen, M and Menzies, J and Monard, LA and Nishiyama, S and Papadakis, I and Street, R and Sumi, T and Williams, A and Yee, JC and Brillant, S and Caldwell, JAR and Cole, A and Cook, KH and Donatowicz, J and Kains, N and Kane, SR and Martin, R and Pollard, KR and Sahu, KC and Tsapras, Y and Wambsganss, J and Zub, M and DePoy, DL and Gaudi, BS and Han, C and Lee, CU and Park, BG and Pogge, RW and Kubiak, M and Szymanski, MK and Pietrzynski, G and Soszynski, I and Szewczyk, O and Ulaczyk, K and Wyrzykowski, L and Abe, F and Fukui, A and Furusawa, K and Gilmore, AC and Hearnshaw, JB and Itow, Y and Kamiya, K and Kilmartin, PM and Korpela, AV and Lin, W and Ling, CH and Masuda, K and Matsubara, Y and Miyake, N and Muraki, Y and Nagaya, M and Ohnishi, K and Okumura, T and Perrott, Y and Rattenbury, NJ and Saito, TO and Sako, T and Sato, S and Skuljan, L and Sullivan, D and Sweatman, W and Tristram, PJ and Yock, PC and Allan, A and Bode, MF and Burgdorf, MJ and Clay, N and Fraser, SN and Hawkins, E and Kerins, E and Lister, TA and Mottram, CJ and Saunders, ES and Snodgrass, C and Steele, IA and Wheatley, PJ and Anguita, T and Bozza, V and Harpsoe, K and Hinse, TC and Hundertmark, M and Kjaergaard, P and Liebig, C and Mancini, L and Masi, G and Rahvar, S and Ricci, D and Scarpetta, G and Southworth, J and Surdej, J and Thone, CC and Riffeser, A and Seitz, S and Bender, R, SR, OGLE 2008-BLG-290: an accurate measurement of the limb darkening of a galactic bulge K Giant spatially resolved by microlensing, Astronomy and Astrophysics, 518, (19) EJ ISSN 0004-6361 (2010) [Refereed Article]

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Copyright © EDP Sciences, 2010

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DOI: doi:10.1051/0004-6361/201014053


Context. Gravitational microlensing is not only a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. Aims. In high magnification events, the lens caustic may cross over the source disk, which allows a determination of the angular size of the source and additionally a measurement of its limb darkening. Methods. When such extended-source effects appear close to maximum magnification, the resulting light curve differs from the characteristic Paczy´nski point-source curve. The exact shape of the light curve close to the peak depends on the limb darkening of the source. Dense photometric coverage permits measurement of the respective limb-darkening coefficients. Results. In the case of microlensing event OGLE 2008-BLG-290, the K giant source star reached a peak magnification of about 100. Thirteen different telescopes have covered this event in eight different photometric bands. Subsequent light-curve analysis yielded measurements of linear limb-darkening coefficients of the source in six photometric bands. The best-measured coefficients lead to an estimate of the source effective temperature of about 4700+100 −200 K. However, the photometric estimate from colour-magnitude diagrams favours a cooler temperature of 4200 ± 100 K. Conclusions. As the limb-darkening measurements, at least in the CTIO/SMARTS2 Vs− and Is− bands, are among the most accurate obtained, the above disagreement needs to be understood. A solution is proposed, which may apply to previous events where such a discrepancy also appeared

Item Details

Item Type:Refereed Article
Keywords:techniques: gravitational microlensing – techniques: high angular resolution – stars: atmosphere models – stars: limb darkening –
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Stellar astronomy and planetary systems
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Greenhill, J (Dr John Greenhill)
UTAS Author:Cole, A (Associate Professor Andrew Cole)
ID Code:66404
Year Published:2010
Web of Science® Times Cited:13
Deposited By:Physics
Deposited On:2011-01-17
Last Modified:2012-03-06

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