We compare the first direct angular diameter measurements obtained on our closest stellar neighbour , \alpha Centauri to recent model diameters constrained by asteroseismic observations .
Using the VINCI instrument installed at ESO ’ s VLT Interferometer ( VLTI ) , the angular diameters of the two main components of the system , \alpha Cen A and B , were measured with a relative precision of 0.2 % and 0.6 % respectively .
Particular care has been taken in the calibration of these measurements , considering that VINCI is estimating the fringe visibility using a broadband K filter .
We obtain uniform disk angular diameters for \alpha Cen A and B of \theta _ { UD } [ A ] = 8.314 \pm 0.016 Â mas and \theta _ { UD } [ B ] = 5.856 \pm 0.027 Â mas , and limb darkened angular diameters of \theta _ { LD } [ A ] = 8.511 \pm 0.020 Â mas and \theta _ { LD } [ B ] = 6.001 \pm 0.034 Â mas .
Combining these values with the parallax from Söderhjelm ( [ ] ) , we derive linear diameters of D [ A ] = 1.224 \pm 0.003 D _ { \odot } and D [ B ] = 0.863 \pm 0.005 D _ { \odot } .
These values are compatible with the masses published by Thévenin et al. ( [ ] ) for both stars .