Thomas E. Harrison et al. 2009 The Astronomical Journal 137 4061 doi:10.1088/0004-6256/137/4/4061
Thomas E. Harrison1,5,6, Jillian Bornak1,6, Steve B. Howell2,5, Elena Mason3, Paula Szkody4 and Rosalie McGurk4
Show affiliationsWe present new K-band spectra of VY Aqr and EI Psc obtained with NIRSPEC on the Keck II telescope. We find a best-fitting spectral type of K4 for EI Psc, in agreement with the previous classification. The Keck spectrum of VY Aqr suggests an M0 spectral type, much hotter than previously derived. We re-reduce the original data for VY Aqr that were obtained using ISAAC on the Very Large Telescope (VLT) and find a best-fitting spectral type of M6 for VY Aqr. We are unable to reconcile the two data sets. We analyze new phase-resolved optical spectroscopy of VY Aqr, obtained using UVES on the VLT, to derive the mass ratio, and show that the mass of its secondary star is very likely below the stellar/substellar boundary. We also present and model phase-resolved JHK infrared light curves for both objects, and g- and I-band light curves for EI Psc. While the light curve models for EI Psc are consistent with its spectral type, we are unable to model the light curves of VY Aqr without assuming binary star parameters outside the published range for this object.
Issue 4 (2009 April)
Received 2008 June 24, accepted for publication 2009 January 23
Published 2009 March 10
Thomas E. Harrison et al. 2009 The Astronomical Journal 137 4061
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