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


Batista, V and Dong, S and Gould, A and Beaulieu, JP and Cassan, A and Christie, GW and Han, C and Udalski, A and Allen, W and DePoy, DL and Gal-Yam, A and Gaudi, BS and Johnson, B and Kaspi, S and Lee, CU and Maoz, D and McCormick, J and McGreer, I and Monard, B and Natusch, T and Ofek, E and Park, BG and Pogge, RW and Polishook, D and Shporer, A and Albrow, MD and Bennett, DP and Brilliant, S and Bode, M and Bramich, DM and Burgdorf, M and Caldwell, JAR and Calitz, H and Cole, AA and Cook, KH and Coutures, C and Dieters, S and Dominik, M and Prester, DD and Donatowicz, J and Fouque, P and Greenhill, JG and Hoffman, M and Horne, K and Jorgensen, UG and Kains, N and Kane, S and Kubas, D and Marquette, JB and Martin, R and Meintjes, P and Menzies, J and Pollard, KR and Sahu, KC and Snodgrass, C and Steele, I and Tsapras, Y and Wambsganss, J and Williams, A and Zub, M and Wyrzykowski, L and Kubiak, M and Szymanski, MK and Pietrzynski, G and Soszynski, I and Szewczyk, O and Ulaczyk, K and Abe, F and Bond, IA and Fukui, A and Furusawa, K and Hearnshaw, JB and Holderness, S and Itow, Y and Kamiya, K and Kilmartin, PM and Korpela, A 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, YC and Rattenbury, N and Saito, T and Sako, T and Skuljan, L and Sullivan, D and Sumi, T and Sweatman, WL and Tristram, PJ and Yock, PCM, Mass measurement of a single unseen star and planetary detection efficiency for OGLE 2007-BLG-050, Astronomy and Astrophysics, 508, (1) pp. 467-478. ISSN 0004-6361 (2009) [Refereed Article]

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Copyright EDP Sciences, 2009

DOI: doi:10.1051/0004-6361/200912923


Aims. We analyze OGLE-2007-BLG-050, a high magnification microlensing event (A~ 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 $\theta_{\rm E}=0.48\pm 0.01$ mas and the parallax $\pi_{\rm E}=0.12\pm 0.03$, leading to an estimate of the lens mass $M=0.50\pm0.14\,M_{\odot}$ and its distance to the observer $D_L=5.5\pm0.4$ 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 $(r_\perp,m_{\rm p})$, where $r_\perp$ is the projected planet-star separation and m_ p 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 $\Delta\chi^2$ 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 [0.610] and [1.44] AU, and Earth-mass planets are excluded with a 10% confidence in the lensing zone, i.e. [1.83.1] AU.

Item Details

Item Type:Refereed Article
Keywords:gravitational lensing-techniques, photometric-stars, individual, OGLE 2007-BLG-050-planetary systems
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cole, AA (Associate Professor Andrew Cole)
UTAS Author:Greenhill, JG (Dr John Greenhill)
ID Code:59560
Year Published:2009
Web of Science® Times Cited:19
Deposited By:Physics
Deposited On:2009-12-10
Last Modified:2011-03-22
Downloads:18 View Download Statistics

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