Mid - infrared interferometry of massive young stellar objects II Evidence for a circumstellar disk surrounding the Kleinmann - Wright object

摘要

The formation scenario for massive stars is still under discussion. Tofurther constrain current theories, it is vital to spatially resolve thestructures from which material accretes onto massive young stellar objects(MYSOs). Due to the small angular extent of MYSOs, one needs to overcome thelimitations of conventional thermal infrared imaging, regarding spatialresolution, in order to get observational access to the inner structure ofthese objects.We employed mid - infrared interferometry, using the MIDIinstrument on the ESO /VLTI, to investigate the Kleinmann - Wright Object, amassive young stellar object previously identified as a Herbig Be starprecursor. Dispersed visibility curves in the N- band (8 - 13 {\mu}m) have beenobtained at 5 interferometric baselines. We show that the mid - infraredemission region is resolved. A qualitative analysis of the data indicates a non- rotationally symmetric structure, e.g. the projection of an inclined disk. Weemployed extensive radiative transfer simulations based on spectral energydistribution fitting. Since SED - only fitting usually yields degenerateresults, we first employed a statistical analysis of the parameters provided bythe radiative transfer models. In addition, we compared the ten best - fittingself - consistent models to the interferometric observations. Our analysis ofthe Kleinmann - Wright Object suggests the existence of a circumstellar disk of0.1M\odot at an intermediate inclination of 76\circ, while an additional dustyenvelope is not necessary for fitting the data. Furthermore, we demonstratethat the combination of IR interferometry with radiative transfer simulationshas the potential to resolve ambiguities arising from the analysis of spectralenergy distributions alone.