OGLE-2008-BLG-510: first automated real-time detection of a weak microlensing anomaly - brown dwarf or stellar binary?

• Published in: Monthly notices of the Royal Astronomical Society Vol. 424; no. 2; pp. 902 - 918
• Main Authors: Bozza, V., Dominik, M., Rattenbury, N. J., Jørgensen, U. G., Tsapras, Y., Bramich, D. M., Udalski, A., Bond, I. A., Liebig, C., Cassan, A., Fouqué, P., Fukui, A., Hundertmark, M., Shin, I.-G., Lee, S. H., Choi, J.-Y., Park, S.-Y., Gould, A., Allan, A., Mao, S., Street, R. A., Buckley, D., Nagayama, T., Mathiasen, M., Hinse, T. C., Calchi Novati, S., Harpsøe, K., Mancini, L., Scarpetta, G., Anguita, T., Burgdorf, M. J., Horne, K., Hornstrup, A., Kains, N., Kerins, E., Kjærgaard, P., Masi, G., Rahvar, S., Ricci, D., Snodgrass, C., Steele, I. A., Surdej, J., Thöne, C. C., Wambsganss, J., Zub, M., Albrow, M. D., Beaulieu, J.-P., Bennett, D. P., Cole, A. A., Cook, K. H., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Greenhill, J., Kane, S. R., Marquette, J.-B., Martin, R., Menzies, J., Pollard, K. R., Sahu, K. C., Williams, A., Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Ulaczyk, K., DePoy, D. L., Dong, Subo, Han, C., Janczak, J., Lee, C.-U., Pogge, R. W., Abe, F., Furusawa, K., Hearnshaw, J. B., Itow, Y., Kilmartin, P. M., Korpela, A. V., Lin, W., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Perrott, Y. C., Saito, To, Skuljan, L., Sullivan, D. J., Sumi, T., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., Gulbis, A., Hashimoto, Y., Kniazev, A., Vaisanen, P.
• Format: Journal Article Web Resource
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.08.2012; Blackwell Publishing Ltd; Oxford University Press; Oxford University Press (OUP): Policy P - Oxford Open Option A; Blackwell Publishing
• Subjects: Astronomy; Astrophysics; Aérospatiale, astronomie & astrophysique; Brown dwarfs; Double stars; gravitational lensing: micro; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; planetary systems; Real time; Sciences of the Universe; Space science, astronomy & astrophysics; gravitational lensing: micro; planetary systems; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1111/j.1365-2966.2012.21233.x

Abstract The microlensing event OGLE-2008-BLG-510 is characterized by an evident asymmetric shape of the peak, promptly detected by the Automated Robotic Terrestrial Exoplanet Microlensing Search (ARTEMiS) system in real time. The skewness of the light curve appears to be compatible both with binary-lens and binary-source models, including the possibility that the lens system consists of an M dwarf orbited by a brown dwarf. The detection of this microlensing anomaly and our analysis demonstrate that: (1) automated real-time detection of weak microlensing anomalies with immediate feedback is feasible, efficient and sensitive, (2) rather common weak features intrinsically come with ambiguities that are not easily resolved from photometric light curves, (3) a modelling approach that finds all features of parameter space rather than just the 'favourite model' is required and (4) the data quality is most crucial, where systematics can be confused with real features, in particular small higher order effects such as orbital motion signatures. It moreover becomes apparent that events with weak signatures are a silver mine for statistical studies, although not easy to exploit. Clues about the apparent paucity of both brown-dwarf companions and binary-source microlensing events might hide here.