A New Method to Calibrate the Stellar Color/Surface-Brightness Relation

TL;DR

This paper introduces a novel method to calibrate stellar color/surface-brightness relations using microlensing data and late-time proper motion measurements, especially benefiting studies of metal-rich stars in the Galactic bulge.

Contribution

It presents a new approach to calibrate stellar relations by inverting microlensing techniques with proper motion data, expanding calibration options for metal-rich stars.

Findings

Identified eight high-metallicity bulge stars suitable for calibration.

Seven of these stars will be calibrators with upcoming Giant Magellan Telescope.

Method can utilize current and future microlensing survey data.

Abstract

I show that the standard microlensing technique to measure the angular radius of a star using color/surface-brightness relations can be inverted, via late-time proper motion measurements, to calibrate these relations. The method is especially useful for very metal-rich stars because such stars are in short supply in the solar neighborhood where other methods are most effective, but very abundant in Galactic bulge microlensing fields. I provide a list of eight spectroscopically identified high-metallicity bulge stars with the requisite finite-source effects, seven of which will be suitable calibrators when the Giant Magellan Telescope comes on line. Many more such sources can be extracted from current and future microlensing surveys.