Selection of Nearby Microlensing Candidates for Observation by SIM
Abstract
I investigate the prospects for using the Space Interferometry Mission (SIM) to measure the masses of nearby stars from their astrometric deflection of more distant sources, as originally suggested by Paczynski and by MiraldaEscude. I derive an analytic expression for the total observing time T_tot required to measure the masses of a fixed number of stars to a given precision. I find that T_tot ~ r_max^{2}, where r_max is the maximum radius to which candidates are searched, or T_tot ~ \mu_min^2, where \mu_min is the minimum proper motion to which candidates are searched. I show that T_tot can be reduced by a factor 4 if source availability is extended from V_s=17 to V_s=19. Increasing r_max and V_s and decreasing \mu_min all require a significantly more agressive approach to finding candidates. A search for candidates can begin by making use of the Luyton proper motion catalog together with the USNOA2.0 allsky astrometric catalog. However, a thorough search would require the allsky USNOB propermotion catalog which is not yet available. The followup observations necessary to prepare for the mission will become more difficult the longer they are delayed because the candidate pairs are typically already within 1" and are getting closer.
 Publication:

arXiv eprints
 Pub Date:
 May 1999
 arXiv:
 arXiv:astroph/9905120
 Bibcode:
 1999astro.ph..5120G
 Keywords:

 Astrophysics
 EPrint:
 16 pages plus 2 figures, submitted to ApJ