MINESweeper: Spectrophotometric Modeling of Stars in the Gaia Era

Phillip A. Cargile, Charlie Conroy, Benjamin D. Johnson, Yuan-Sen Ting, Ana Bonaca, Aaron Dotter

Published 2019-07-17Version 1

We present MINESweeper, a tool to measure stellar parameters by jointly fitting observed spectra and broadband photometry to model isochrones and spectral libraries. This approach enables the measurement of spectrophotometric distances, in addition to stellar parameters such as Teff, log(g), [Fe/H], [alpha/Fe], and radial velocity. MINESweeper employs a Bayesian framework and can easily incorporate a variety of priors, including Gaia parallaxes. Mock data are fit in order to demonstrate how the precision of derived parameters depends on evolutionary phase and SNR. We then fit a selection of data in order to validate the model outputs. Fits to the benchmark stars Procyon, Arcturus, and the Sun result in derived stellar parameters that are in excellent agreement with the literature, except for the surface gravity of Arcturus, where our value (1.35) is notably lower than the literature (1.66). We then fit combined spectra and photometry of stars in the open and globular clusters M92, M13, M3, M107, M71, and M67. Derived distances, [Fe/H], [alpha/Fe], and log(g)-Teff, relations are in overall good agreement with literature values, although there are trends between metallicity and log(g), within clusters that point to systematic uncertainties at the ~0.1 dex level. Finally, we fit a large sample of stars from the H3 Spectroscopic Survey in which high quality Gaia parallaxes are also available. These stars are fit without the Gaia parallaxes so that the geometric parallaxes can serve as an independent test of the spectrophotometric distances. Comparison between the two reveals excellent agreement within their formal uncertainties after accounting for the Gaia zero point uncertainties.