Open AccessThe effect of a binary source companion on the astrometric microlensing behaviour
Author(s) -
Han Cheongho
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04903.x
Subject(s) - gravitational microlensing , physics , centroid , binary number , light curve , astrophysics , gravitational lens , astrometry , component (thermodynamics) , light source , event (particle physics) , lens (geology) , astronomy , stars , optics , galaxy , artificial intelligence , computer science , arithmetic , mathematics , redshift , thermodynamics
If gravitational microlensing occurs in a binary source system, both source components are magnified, and the resulting light curve deviates from the standard one of a single source event. However, in most cases only one source component is highly magnified and the other component (the companion) can be treated as a simple blending source: this is a blending approximation. In this paper we show that, unlike the light curves, the astrometric curves, representing the trajectories of the source image centroid, of an important fraction of binary source events will not be sufficiently well‐modelled by the blending effect alone. This is because the centroid shift induced by the source companion endures to considerable distances from the lens. Therefore, in determining the lens parameters from astrometric curves to be measured by future high‐precision astrometric instruments, it will be important to take the full effect of the source companion into consideration.