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The MPIA conference series
at Ringberg Castle
The MPIA conference series
at Ringberg Castle
 
EPoS 2016 Suggested Contribution
A Keplerian-like disk around the forming O-type star AFGL 4176

Katharine Johnston
U Leeds, Leeds, UK
I will present our ALMA line and continuum observations at 1.2mm with ~0.3" resolution that uncover a Keplerian-like disk around the forming O-type star AFGL 4176. The first-moment maps, pixel-to-pixel line modelling and position-velocity diagrams of the CH3CN J = 13-12 K-line emission all show a velocity gradient along the major axis of the source, coupled with an increase in velocity at small radii, consistent with Keplerian-like rotation. I will also present APEX 12CO observations that show a large-scale outflow from AFGL4176 perpendicular to the major axis of mm1, supporting the disk interpretation. Finally, I will present our radiative transfer modelling of the ALMA data, showing that a Keplerian disk surrounding an O7 star, with a disk mass and radius of 12 Msol and 2000 AU that reproduces the line and continuum data, further supporting our conclusion that our observations have uncovered a Keplerian-like disk around an O-type star.
Caption: First-moment map of the CH3CN J = 13-12, K = 3 emission from AFGL 4176 mm1 in colourscale. The contours show 1.2mm continuum emission (starting at 10sigma). The beam is shown in the bottom left corner. A gradient in velocity of the CH3CN line is clearly seen along the major axis of the continuum emission, exhibiting that expected from a Keplerian velocity field, where the peak velocities are seen either side of the continuum peak position (Figure adapted from Johnston et al. 2015).
Collaborators:
T. Robitaille, MPIA, DE
H. Beuther, MPIA, DE
H. Linz, MPIA, DE
P. Boley, Ural Federal U, RU
R. Kuiper, MPIA/Eberhard Karls U, DE
E. Keto, Harvard-Smithsonian CfA, US
M. Hoare, U Leeds, GB
Key publication

Suggested Session: Massive Star Formation