Spitzer 24 μm time series observations of the eclipsing M dwarf binary GU Boötis

Creators: von Braun, Kaspar; van Belle, Gerard T.; Ciardi, David R.; López-Morales, Mercedes; Hoard, D. W.; Wachter, Stefanie

Abstract

We present a set of Spitzer 24 μm MIPS time series observations of the M dwarf eclipsing binary star GU Boötis. Our data cover three secondary eclipses of the system: two consecutive events and an additional eclipse 6 weeks later. The study's main purpose is the long-wavelength (and thus limb-darkening-independent) characterization of GU Boo's light curve, allowing for independent verification of the results of previous optical studies. Our results confirm previously obtained system parameters. We further compare GU Boo's measured 24 μm flux density to the value predicted by spectral fitting and find no evidence for circumstellar dust. In addition to GU Boo, we characterize (and show examples of) light curves of other objects in the field of view. Analysis of these light curves serves to characterize the photometric stability and repeatability of Spitzer's MIPS 24 μm array over short (days) and long (weeks) timescales at flux densities between approximately 300 and 2000 μJy. We find that the light-curve rms about the median level falls into the 1%-4% range for flux densities higher than 1 mJy. Finally, we comment on the fluctuations of the 24 μm background on short and long timescales.

Additional Information

© 2008 The American Astronomical Society. Received 2007 August 6; accepted 2007 December 24. We gratefully acknowledge the allocation of Spitzer Director's Discretionary Time (DDT) for this project.We furthermore thank D. Frayer, S. Carey, J. Colbert, and P. Lowrance for providing valuable insight into the mysterious world of MOPEX and APEX, as well as the anonymous referee for the thorough study of the manuscript, and some very insightful comments and suggestions that significantly improved the quality of this publication. Thanks also to J. Southworth for useful clarifications on the use of JKTEBOP, and to M. Cushing for providing the IRS spectrum of GL 229A in electronic format. This research has made use of NASA's Astrophysics Data System. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, NASA, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSSWeb site is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, the Astrophysical Institute Potsdam, the University of Basel, the University of Cambridge, Case Western Reserve University, the University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, the University of Pittsburgh, the University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.

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