HD 101088, AN ACCRETING 14 AU BINARY IN LOWER CENTAURUS CRUX WITH VERY LITTLE CIRCUMSTELLAR DUST

We present high-resolution (R = 55, 000) optical spectra obtained with MIKE on the 6.5 m Magellan Clay Telescope as well as Spitzer MIPS photometry and Infrared Spectrometer low-resolution (R ∼ 60) spectroscopy of the close (14 AU separation) binary, HD 101088, a member of the ∼12 Myr old southern region of the Lower Centaurus Crux subgroup of the Scorpius-Centaurus OB association. We find that the primary and/or secondary is accreting from a tenuous circumprimary and/or circumsecondary disk despite the apparent lack of a massive circumbinary disk. We estimate a lower limit to the accretion rate of M-dot > 1x10-9 Msun yr-1, which our multiple observation epochs show varies over a timescale of months. The upper limit on the 70 μm flux allows us to place an upper limit on the mass of dust grains smaller than several microns present in a circumbinary disk of 0.16 Mmoon. We conclude that the classification of disks into either protoplanetary or debris disks based on fractional infrared luminosity alone may be misleading.