A Sub-milli-arcsecond View of the Gas-Dust transition Region in Herbig Ae Stars
First Author:
Ajay-Kumar Tannirkulam
Email: atannirk AT umich.edu
University of Michigan
1017 Dennison Bldg., 500 Church Street
Ann Arbor, MI -48109 , USA
Coauthors:
Monnier, John, U. Michigan
Harries, Tim, U. Exeter
Millan-Gabet, Rafael, Michelson Science Center
Pedretti, E., U. St. Andrews
Zhu, Z., U. Michigan
Brummelaar, Theo, CHARA Array, GSU
Abstract
Contrary to the predictions of 'standard' models, we have detected strong near-infrared (NIR) emission from hot gas in the prototype Herbig Ae stars MWC 275 and AB Aur. Using the sub-milli-arcsecond resolution of the CHARA interferometer array, we place the gas emission to be interior to and on the same spatial scale as the dust sublimation radius. In the absence of shielding of starlight by gas, we demonstrate that the dust evaporation front in these young stellar objects (YSOs) will have to contain highly refractory dust sublimating at ~1850K. MWC 275 and AB Aur have very similar structures in the thermal NIR, and yet their outer disks are substantially different. As opposed to MWC 275, AB Aur has a substantial amount of small dust grains in the disk atmosphere even beyond 10 AU that produce significant 10-20 micron emission, indicating the presence planetesimal collisions that maintain the small grain population.
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