Potential direct single-star mass measurement

H Ghosh, D L DePoy, A Gal-Yam, B S Gaudi, A Gould, C Han, Y Lipkin, D Maoz, E O Ofek, B G Park, R W Pogge, S Salim, F Abe, D P Bennett, I A Bond, S Eguchi, Y Furuta, J B Hearnshaw, K Kamiya, P M KilmartinY Kurata, K Masuda, Y Matsubara, Y Muraki, S Noda, K Okajima, N J Rattenbury, T Sako, T Sekiguchi, D J Sullivan, T Sumi, P J Tristram, T Yanagisawa, P C M Yock, A Udalski, I Soszynski, X Wyrzykowski, M Kubiak, M K Szymanski, G Pietrzynski, O Szewczyk, K Zebrun, M D Albrow, J P Beaulieu, J A R Caldwell, A Cassan, C Coutures, M Dominik, J Donatowicz, P Fouque, J Greenhill, K Hill, K Horne, U G Jorgensen, S Kane, D Kubas, R Martin, J Menzies, K R Pollard, K C Sahu, J Wambsganss, R Watson, A Williams

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

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 (r) over tilde (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 mu(rel) and so the mass M=(c(2)/4G)mu(rel)t(E)(r) over tilde (E), where t(E) is the measured Einstein timescale. While the light-curve-based measurement of (r) over tildeE is, by itself, severely degenerate, we show that this degeneracy can be completely resolved by measuring the direction of proper motion mu(rel).

Original languageEnglish
Pages (from-to)450-459
Number of pages10
JournalAstrophysical Journal Letters
Volume615
Publication statusPublished - 1 Nov 2004

Keywords

  • astrometry
  • gravitational lensing
  • stars : fundamental parameters
  • GRAVITATIONAL LENSING EXPERIMENT
  • LARGE-MAGELLANIC-CLOUD
  • PARALLAX MICROLENS DEGENERACY
  • SPACE-INTERFEROMETRY-MISSION
  • DIFFERENCE IMAGE-ANALYSIS
  • GALACTIC BULGE
  • EVENT
  • HALO
  • EXTINCTION
  • PHOTOMETRY

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