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Published September 20, 2012 | Published
Journal Article Open

Constraining Mass Ratio and Extinction in the FU Orionis Binary System with Infrared Integral Field Spectroscopy


We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0".5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 μm interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, A_V = 8-12, with an effective temperature of ~4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

Additional Information

© 2012 American Astronomical Society. Received 2012 March 28; accepted 2012 July 6; published 2012 September 5. The research described in this publication was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Project 1640 is funded by National Science Foundation grants AST-0520822, AST-0804417, and AST-0908484. This work was partially funded through the NASA ROSES Origins of Solar Systems Grant NMO710830/ 102190, the NSF AST-0908497 Grant. The adaptive optics program at Palomar is supported by NSF grants AST-0619922 and AST-1007046. L.P. was supported by an appointment to the NASA Postdoctoral Program at the JPL, Caltech, administered by Oak Ridge Associated Universities through a contract with NASA. L.P. and S.H. performed this work in part under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program. This work was based in part on data collected at the Subaru Telescope and obtained from the SMOKA, which is operated by the Astronomy Data Center, National Observatory of Japan.

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