Resolving the inner active accretion disk around the Herbig Be star MWC 147 with VLTI/MIDI+AMBER spectro-interferometry

TL;DR

This study combines near- and mid-infrared spectro-interferometry to analyze the inner accretion disk of the Herbig Be star MWC 147, revealing that the NIR emission is dominated by an optically thick gaseous disk, with MIR emission from the outer dust disk.

Contribution

First combined NIR and MIR spectro-interferometry data for a Herbig star, providing detailed geometric and temperature distribution constraints of the inner disk.

Findings

NIR emission is dominated by an optically thick gaseous accretion disk.

MIR emission includes significant contributions from the outer dust disk.

Passive irradiated Keplerian dust disks alone cannot explain observed visibilities.

Abstract

We studied the geometry of the inner (AU-scale) circumstellar environment around the Herbig Be star MWC 147. Combining, for the first time, near- (NIR, K band) and mid-infrared (MIR, N band) spectro-interferometry on a Herbig star, our VLTI/MIDI and AMBER data constrain not only the geometry of the brightness distribution, but also the radial temperature distribution in the disk. For our detailed modeling of the interferometric data and the spectral energy distribution, we employ 2-D radiation transfer simulations, showing that passive irradiated Keplerian dust disks can easily fit the SED, but predict much lower visibilities than observed. Models of a Keplerian disk with emission from an optically thick inner gaseous accretion disk (inside the dust sublimation zone), however, yield a good fit of the SED and simultaneously reproduce the observed NIR and MIR visibilities. We conclude that the NIR continuum emission from MWC 147 is dominated by accretion luminosity emerging from an optically thick inner gaseous disk, while the MIR emission also contains strong contributions from the outer dust disk.