SpringerLink
Forum Springer Astron. Astrophys.
Forum Whats New Search Orders


Astron. Astrophys. 333, 893-896 (1998)

Previous Section Next Section Title Page Table of Contents

2. Point-mass lens and point source

For a lens at a distance [FORMULA] from the observer, a source at a distance [FORMULA] from the observer, and [FORMULA] the lens-source distance, the Einstein radius for a lens of mass M is given by

[EQUATION]

Let the lens move on a straight line with a velocity [FORMULA] transverse to the line-of-sight observer-source, so that it moves one Einstein radius in the lens plane in the time [FORMULA]. 1 Let [FORMULA] denote the time at the closest approach and [FORMULA] the impact parameter at [FORMULA] in units of Einstein radii. For the impact parameter at time t one obtains

[EQUATION]

where

[EQUATION]

The light amplification for a point source and a point-mass lens is given by

[EQUATION]

Previous Section Next Section Title Page Table of Contents

© European Southern Observatory (ESO) 1998

Online publication: April 28, 1998

helpdesk.link@springer.de