EPoS Contribution
EPoS 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).
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