Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050**********

Aims. We analyze OGLE-2007-BLG-050, a high magnification microlensing event (432) whose peak occurred on 2 May, 2007, with pronounced finite-source and parallax effects. We compute planet detection efficiencies for this event in order to determine its sensitivity to the presence of planets around the lens star.Methods. Both finite-source and parallax effects permit a measurement of the angular Einstein radius E=0.480.01 mas and the parallax E=0.120.03, leading to an estimate of the lens mass M=0.500.14 M and its distance to the observer DL=5.50.4 kpc. This is only the second determination of a reasonably precise (<30%) mass estimate for an isolated unseen object, using any method. This allows us to calculate the planetary detection efficiency in physical units (r,m), where r is the projected planet-star separation and mp is the planet mass.Results. When computing planet detection efficiency, we did not find any planetary signature, i.e. none of the planetary configurations provides a X 2 improvement higher than 60, and our detection efficiency results reveal significant sensitivity to Neptune-mass planets, and to a lesser extent Earth-mass planets in some configurations. Indeed, Jupiter and Neptune-mass planets are excluded with a high confidence for a large projected separation range between the planet and the lens star, respectively [0.6-10] and [1.4-4] AU, and Earth-mass planets are excluded with a 10% confidence in the lensing zone, i.e. [1.8-3.1] AU. 2009 ESO.

Batista, V., Dong, S., Gould, A., Beaulieu, J. P., Cassan, A., Christie, G. W., ... Yock, P.

Batista, V||Dong, S||Gould, A||Beaulieu, JP||Cassan, A||Christie, GW||Han, C||Udalski, A||Allen, W||DePoy, DL||Gal-Yam, A||Gaudi, BS||Johnson, B||Kaspi, S||Lee, CU||Maoz, D||McCormick, J||McGreer, I||Monard, B||Natusch, T||Ofek, E||Park, B-G||Pogge, RW||Polishook, D||Shporer, A||Albrow, MD||Bennett, DP||Brillant, S||Bode, M||Bramich, DM||Burgdorf, M||Caldwell, JAR||Calitz, H||Cole, A||Cook, KH||Coutures, Ch||Dieters, S||Dominik, M||Prester, DD||Donatowicz, J||Fouqué, P||Greenhill, J||Hoffman, M||Horne, K||Jørgensen, UG||Kains, N||Kane, S||Kubas, D||Marquette, JB||Martin, R||Meintjes, P||Menzies, J||Pollard, KR||Sahu, KC||Snodgrass, C||Steele, I||Tsapras, Y||Wambsganss, J||Williams, A||Zub, M||Wyrzykowski, Ł||Kubiak, M||Szymański, MK||Pietrzyński, G||Soszyński, I||Szewczyk, O||Ulaczyk, K||Abe, F||Bond, IA||Fukui, A||Furusawa, K||Hearnshaw, JB||Holderness, S||Itow, Y||Kamiya, K||Kilmartin, PM||Korpela, A||Lin, W||Ling, CH||Masuda, K||Matsubara, Y||Miyake, N||Muraki, Y||Nagaya, M||Ohnishi, K||Okumura, T||Perrott, YC||Rattenbury, N||Saito, T||Sako, T||Skuljan, L||Sullivan, D||Sumi, T||Sweatman, WL||Tristram, PJ||Yock, PCM

Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050********** Academic Article