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

Abstract

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 7.5−13 μ m. 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 deg) and position angle (∼107 deg). 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 20 M ⊙ . 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 SED.