Sunday, November 9, 2014

Characterizing Host Stars to be Surveyed by the Korean Microlensing Telescope Network

Prospects for Characterizing Host Stars of the Planetary System Detections Predicted for the Korean Microlensing Telescope Network

Author:

Henderson

Abstract:

I investigate the possibility of constraining the flux of the lens (i.e., host star) for the types of planetary systems the Korean Microlensing Telescope Network is predicted to find. I examine the potential to obtain lens flux measurements by 1) imaging a lens once it is spatially resolved from the source, 2) measuring the elongation of the point spread function of the microlensing target (lens+source) when the lens and source are still unresolved, and 3) taking prompt follow-up photometry. In each case I simulate observing programs for a representative example of current ground-based adaptive optics (AO) facilities (specifically NACO on VLT), future ground-based AO facilities (GMTIFS on GMT), and future space telescopes (NIRCAM on JWST). Given the predicted distribution of relative lens-source proper motions, I find that the lens flux could be measured to a precision of σHℓ≤0.1 for ≳60% of planet detections ≥5 years after each microlensing event, for a simulated observing program using GMT that images resolved lenses. NIRCAM on JWST would be able to carry out equivalently high-precision measurements for ∼28% of events Δt = 10 years after each event by imaging resolved lenses. I also explore the effects various blend components would have on the mass derived from prompt follow-up photometry, including companions to the lens, companions to the source, and unassociated interloping stars. I find that undetected blend stars would cause catastrophic failures (i.e., greater than 50% fractional uncertainty in the inferred lens mass) for ≲(16⋅fbin)% of planet detections, where fbin is the binary fraction, with the majority of these failures occurring for host stars with mass ≲0.3M⊙.

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