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Combined analysis of the binary lens caustic-crossing event MACHO 98-SMC-1

Authors

Afonso, C Alard, C Albert, JN Andersen, J Ansari, R Aubourg, E Bareyre, P Bauer, F Beaulieu, JP Bouquet, A Char, S Charlot, X Couchot, F Coutures, C Derue, F Ferlet, R Glicenstein, JF Goldman, B Gould, A Graff, D Gros, M Haissinski, J Hamilton, JC Hardin, D de Kat, J Kim, A Lasserre, T Lesquoy, E Loup, C Magneville, C Marquette, JB Maurice, E Milsztajn, A Moniez, M Palanque-Delabrouille, N Perdereau, O Prevot, L Regnault, N Rich, J Spiro, M Vidal-Madjar, A Vigroux, L Zylberajch, S Alcock, C Allsman, RA Alves, D Axelrod, TS Becker, AC Cook, KH Drake, AJ Freeman, KC Griest, K King, LJ Lehner, MJ Marshall, SL Minniti, D Peterson, BA Pratt, MR Quinn, PJ Rodgers, AW Stetson, PB Stubbs, CW Sutherland, W Tomaney, A Vandehei, T Rhie, SH Bennett, DP Fragile, PC Johnson, BR Quinn, J Udalski, A Kubiak, M Szymanski, M Pietrzynski, G Wozniak, P Zebrun, K Albrow, MD Caldwell, JAR DePoy, DL Dominik, M Gaudi, BS Greenhill, J Hill, K Kane, S Martin, R Menzies, J Naber, RM Pogge, RW Pollard, KR Sackett, PD Sahu, KC Vermaak, P Watson, R Williams, A

Citation

C. Afonso et al., Combined analysis of the binary lens caustic-crossing event MACHO 98-SMC-1, ASTROPHYS J, 532(1), 2000, pp. 340-352

Citations number

Categorie Soggetti

Space Sciences

Journal title

ASTROPHYSICAL JOURNAL

ISSN journal

0004637X → ACNP

Volume

532

Issue

Year of publication

2000

Part

Pages

340 - 352

Database

ISI

SICI code

0004-637X(20000320)532:1<340:CAOTBL>2.0.ZU;2-1

Abstract

We fit the data for the binary lens microlensing event MACHO 98-SMC-1 from five different microlensing collaborations and find two distinct solutions characterized by binary separation d and mass ratio q: (d, q) = (0.54, 0.50 ) and (d, q) = (3.65, 0.36), where d is in units of the Einstein radius. Ho wever, the relative proper motion of the lens is very similar in the two so lutions, 1.30 km s(-1) kpc(-1) and 1.48 km s(-1) kpc(-1), thus confirming t hat the lens is in the Small Magellanic Cloud. The close binary can be eith er rotating or approximately static but the wide binary must be rotating at close to its maximum allowed rate to be consistent with all the data. We m easure limb-darkening coefficients for five bands ranging from I to V. As e xpected, these progressively decrease with rising wavelength. This is the f irst measurement of limb darkening for a metal-poor A star.