Table 6
Physical parameters of Achernar derived from the fit of the RVZ model (CHARRON code) to VLTI/PIONIER H band data using the MCMC method (emcee code).
| Free model parameters fitted | Values and uncertainties |
|
|
|
| Equatorial radius: Req(R⊙)a | 9.16 (+ 0.23; -0.23) |
| Equatorial rotation velocity: Veq(km s-1) | 298.8 (+ 6.9; -5.5) |
| Rotation-axis inclination angle: i (°) | 60.6 (+ 7.1; -3.9) |
| Gravity-darkening coefficient: β | 0.166 (+ 0.012; -0.010) |
| Position angle of the visible pole: PArot (°) | 216.9 (+ 0.4; -0.4) |
|
|
|
| Derived parameters | Values |
|
|
|
| Equatorial angular diameter: ⌀eq = 2Req/d (mas) | 1.99 |
| Polar radius: Rp(R⊙) | 6.78 |
| Req/Rp; ϵ ≡ 1− Rp/Req | 1.352;0.260 |
| Apparent flattening (major to minor axis ratio) | 1.30 |
Mean angular diameter: 
(mas) |
1.77 |
| Veqsini (km s-1) | 260.3 |
| Critical rotation rateb: Veq/Vc; Ω / Ωc | 0.883; 0.980 |
| Keplerian rotation ratec: Veq/Vk; Ω / Ωk | 0.838; 0.838 |
| Polar temperature: Tp (K) | 17 124 |
| Equatorial temperature: Teq (K) | 12 673 |
| Luminosity: log L/L⊙ | 3.480 |
| Equatorial gravity: log geq | 2.772 |
| Polar gravity: log gp | 3.561 |
| Rotation period: Prot (h) | 37.25 |
| Rotation frequency: νrot (d-1) | 0.644 |
Notes.Details of the fit are given in Sect. 4.2.
The uncertainty in the distance d from van Leeuwen (2007) was added quadratically to the fit uncertainty on Req.
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