A multi-wavelength interferometric study of the massive young stellar object IRAS 13481-6124

We present new mid-infrared interferometric observations of the massive young stellar object IRAS 13481-6124, using VLTI/MIDI for spectrally-resolved, long-baseline measurements (projected baselines up to ~120 m) and GSO/T-ReCS for aperture-masking interferometry in five narrow-band filters (projected baselines of ~1.8-6.4 m) in the wavelength range of 7.5-13μm. We combine these measurements with previously-published interferometric observations in the K and N bands in order to assemble the largest collection of infrared interferometric observations for a massive YSO to date. Using a combination of geometric and radiative-transfer models, we confirm the detection at mid-infrared wavelengths of the disk previously inferred from near-infrared observations. We show that the outflow cavity is also detected at both near- and mid-infrared wavelengths, and in fact dominates the mid-infrared emission in terms of total flux. For the disk, we derive the inner radius (~1.8 mas or ~6.5 AU at 3.6 kpc), temperature at the inner rim (~1760 K), inclination (~48°) and position angle (~107°). We determine that the mass of the disk cannot be constrained without high-resolution observations in the (sub-)millimeter regime or observations of the disk kinematics, and could be anywhere from ~10^-3 to 20M_⊙. Finally, we discuss the prospects of interpreting the spectral energy distributions of deeply-embedded massive YSOs, and warn against attempting to infer disk properties from the spectral energy distribution.

Based in part on observations with the Very Large Telescope Interferometer of the European Southern Observatory, under program IDs 384.C-0625, 086.C-0543, 091.C-0357.