(Proposal ID) S12B-015

(PI) Takami, Michihiro

(Proposal Title)
Revealing accretion and evolution of heavily embedded high-mass protostars

(Abstract)
While the formation of low mass protostars is relatively well understood, the 
theoretical and observational understanding of the formation of high mass stars
 has remained a tricky puzzle. Disk accretion is regarded as the most promising
 formation scenario, however, prior observations have not provided convincing 
evidence that accretion from the innermost disk region to the protostar is 
ongoing.  Furthermore, the high extinction in these objects makes observing 
emission arising directly from the protostar and inner disk very challenging, 
leading to ambiguous estimates of their mass and evolutionary status. Our 
recent analysis has suggested that the extended infrared emission associated 
with many high mass protostars is due to scattered continuum. This makes 
emission from the inner disk region or protostar accessible through 
observations of the scattered light. We therefore propose the innovative 
technique of measuring their infrared spectra to 1) confirm the nature of the 
emission; 2) establish the spectral classification and therefore the 
evolutionary status and 3) determine suitable features for probing ongoing 
mass accretion.