MOA-2011-BLG-322Lb: a 'second generation survey' microlensing planet. Issue 1 (30th January 2014)

• Record Type: Journal Article
• Authors: Shvartzvald, Y.; Maoz, D.; Kaspi, S.; Sumi, T.; Udalski, A.; Gould, A.; Bennett, D. P.; Han, C.; Abe, F.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sweatman, W. L.; Suzuki, D.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; Skowron, J.; Kozłowski, S.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Poleski, R.; Pietrukowicz, P.;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 439:Issue 1(2014)
• Page Start: 604
• Page End: 610
• Publication Date: 2014-01-30
• Subjects: gravitational lensing: micro -- surveys -- binaries: general -- planetary systems -- Galaxy: stellar content; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stt2477
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: Global 'second-generation' microlensing surveys aim to discover and characterize extrasolar planets and their frequency, by means of round-the-clock high-cadence monitoring of a large area of the Galactic bulge, in a controlled experiment. We report the discovery of a giant planet in microlensing event MOA-2011-BLG-322. This moderate-magnification event, which displays a clear anomaly induced by a second lensing mass, was inside the footprint of our second-generation microlensing survey, involving MOA, OGLE and the Wise Observatory. The event was observed by the survey groups, without prompting alerts that could have led to dedicated follow-up observations. Fitting a microlensing model to the data, we find that the time-scale of the event was t E = 23.2 ± 0.8 d, and the mass ratio between the lens star and its companion is q = 0.028 ± 0.001. Finite-source effects are marginally detected, and upper limits on them help break some of the degeneracy in the system parameters. Using a Bayesian analysis that incorporates a Galactic structure model, we estimate the mass of the lens at $0.39^{+0.45}_{-0.19}\, {\rm M}_{\odot }$, at a distance of 7.56 ± 0.91 kpc. Thus, the companion is likely a planet of mass $11.6^{+13.4}_{-5.6}\, M_{\rm J}$, at a projected separation of $4.3^{+1.5}_{-1.2}$ au, rather far beyond the snow line. This is the first pure-survey planet reported from a second-generation microlensing survey, and shows that survey data alone can be sufficient to characterize a planetary model. With the detection of additional survey-only planets, we will be able to constrain the frequency of extrasolar planets near their systems' snow lines.