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Gravitational Microlensing, The Distance Scale, And The Ages

Published online by Cambridge University Press:  25 May 2016

Bohdan Paczyński
Bohdan Paczyński*
Affiliation:
Princeton University Observatory, 124 Peyton Hall, Princeton, NJ 08544-1001, USA

Abstract

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A high optical depth to gravitational microlensing towards the galactic bulge is consistent with current models of the galactic bar. The low optical depth towards the LMC can probably be accounted for by the ordinary stars in our galaxy and in the LMC itself. No conclusive evidence is available yet for the presence or absence of a large number of brown dwarfs or other non-stellar compact objects which might account for the dark matter. There is little doubt that the amount of mass in objects in the range 10–8 ≤ M/M⊙ ≤ 106 will be determined within the next few years with the continuing and expanding searches.

Billions of photometric measurements generated by the microlensing searches have lead to the discovery of ∼ 105 variable stars. In particular, a number of detached eclipsing binaries were discovered in the galactic bulge, in the LMC, and in the globular cluster Omega Centauri. The follow-up observations of these binaries will allow the determination of accurate distances to all these objects, as well as robust age determination of globular clusters.

Type
Chapter 7: Microlensing In the Galaxy
Information
Symposium - International Astronomical Union , Volume 173: Astrophysical Applications of Gravitational Lensing , 1996 , pp. 199 - 208
Copyright
Copyright © Kluwer 1996 

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