The Spitzer 24-micron Photometric Light Curve of the Eclipsing M-dwarf Binary GU Bootis

TL;DR

This study uses Spitzer 24-micron observations to analyze the eclipsing binary GU Boo, providing a long-wavelength perspective that confirms optical results and assesses the stability of the instrument.

Contribution

It offers the first mid-infrared light curve of GU Boo, independently verifying optical system parameters and characterizing Spitzer's photometric stability at relevant flux levels.

Findings

Mid-infrared light curves agree with optical parameters.

Spitzer's MIPS-24 shows 1-4% RMS stability for fluxes >1 mJy.

Photometric stability characterized across field objects.

Abstract

We present a carefully controlled set of Spitzer 24 \micron MIPS time series observations of the low mass eclipsing binary star GU Bo\"otis (GU Boo). Our data cover three secondary eclipses of the system: two consecutive events and an additional eclipse six weeks later. The study's main purpose is the long wavelength characterization of GU Boo's light curve, independent of limb darkening and less sensitive to surface features such as spots. Its analysis allows for independent verification of the results of optical studies of GU Boo. Our mid-infrared results show good agreement with previously obtained system parameters. In addition, the analysis of light curves of other objects in the field of view serves to characterize the photometric stability and repeatability of {\it Spitzer's} MIPS-24 at flux densities between approximately 300--2,000$\mu$Jy. We find that the light curve root mean square about the median level falls into the 1--4% range for flux densities higher than 1 mJy.