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Potential Direct Single-Star Mass Measurement


Ghosh, H and DePoy, DL and Gal-Yam, A and Gaudi, BS and Gould, A and Han, C and Lipkin, Y and Maoz, D and Ofek, EO and Park, BG and Pogge, RW and Salim, S and Abe, F and Bennett, DP and Bond, IA and Eguchi, S and Furuta, Y and Hearnshaw, JB and Kamiya, K and Kilmartin, PM and Kurata, Y and Masuda, K and Matsubara, Y and Muraki, Y and Noda, S and Okajima, K and Rattenbury, NJ and Sako, T and Sekiguchi, T and Sullivan, DJ and Sumi, T and Tristram, PJ and Yanagisawa, T and Yock, PCM and Udalski, A and Soszynski, I and Wyrzykowski, L and Kubiak, M and Szymanski, MK and Pietrzynski, G and Szewczyk, O and Zebrun, K and Albrow, MD and Beaulieu, JP and Caldwell, JAR and Cassan, A and Coutures, C and Dominik, M and Donatowicz, J and Fouque, P and Greenhill, JG and Hill, KM and Horne, K and Jorgensen, UG and Kane, S and Kubas, D and Martin, R and Menzies, J and Pollard, KR and Sahu, KC and Wambsganss, J and Watson, RD and Williams, A, Potential Direct Single-Star Mass Measurement, The Astrophysical Journal, 615, (1) pp. 450-459. ISSN 0004-637X (2004) [Refereed Article]

DOI: doi:10.1086/423665


We analyze the light curve of the microlensing event OGLE-2003-BLG-175/MOA- 2003-BLG-45 and show that it has two properties that, when combined with future high-resolution astrometry, could lead to a direct, accurate measurement of the lens mass. First, the light curve shows clear signs of distortion due to the Earth's accelerated motion, which yields a measurement of the projected Einstein radius r̃ E. Second, from precise astrometric measurements, we show that the blended light in the event is coincident with the microlensed source to within about 15 mas. This argues strongly that this blended light is the lens and hence opens the possibility of directly measuring the lens-source relative proper motion μ rel and so the mass M = (c 2/4G)μ relt Er̃ E, where t E is the measured Einstein timescale. While the light-curve-based measurement of r̃ E is, by itself, severely degenerate, we show that this degeneracy can be completely resolved by measuring the direction of proper motion μ rel.

Item Details

Item Type:Refereed Article
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:Greenhill, JG (Dr John Greenhill)
UTAS Author:Hill, KM (Dr Kym Hill)
UTAS Author:Watson, RD (Dr Bob Watson)
ID Code:30816
Year Published:2004
Web of Science® Times Cited:30
Deposited By:Physics
Deposited On:2004-08-01
Last Modified:2005-06-06

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