The radii and limb darkenings of α Centauri A and B - Interferometric measurements with VLTI/PIONIER

P. Kervella; L. Bigot; A. Gallenne; F. Thévenin

doi:10.1051/0004-6361/201629505

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Volume 597 (January 2017)

A&A, 597 (2017) A137

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Table 3

Uniform and limb darkened disk model parameters for α Cen A, α Cen B and the Sun.

	α Cen A (G2V)			α Cen B (K1V)			Sun (G2V)

LD model	LD parameters	θ_LD(A) [mas]^a		LD parameters	θ_LD(B) [mas]^a		Observed LD

Uniform	−	8.347 ± 0.004 ± 0.035	15.23	−	5.883 ± 0.003 ± 0.025	14.26	−

Linear (fixed)^b	u = 0.2392 (fixed)	8.505 ± 0.003 ± 0.036	5.50	u = 0.2698 (fixed)	6.003 ± 0.002 ± 0.025	4.69	u_⊙ = 0.2227 ± 0.0005

Linear (fit)	u = 0.1761 ± 0.0062	8.458 ± 0.005 ± 0.035	4.24	u = 0.1907 ± 0.0048	5.962 ± 0.003 ± 0.025	2.89	u_⊙ = 0.2227 ± 0.0005

Quadratic	a = + 0.191 ± 0.026	8.451 ± 0.013 ± 0.035	4.25				a_⊙ = + 0.0908 ± 0.0004
	b = −0.031 ± 0.054						b_⊙ = + 0.2309 ± 0.0007

Square root	c = + 0.29 ± 0.15	8.446 ± 0.017 ± 0.035	4.24				c_⊙ = −0.2257 ± 0.0004
	d = −0.19 ± 0.25						d_⊙ = + 0.7230 ± 0.0006

4 param. (fixed)^c	a₁ = + 0.7127	8.540 ± 0.003 ± 0.036	4.98	a₁ = + 0.7353	6.030 ± 0.002 ± 0.025	3.93	a_{1 ⊙} = + 0.9789 ± 0.0069
	a₂ = −0.0452			a₂ = −0.0144			a_{2 ⊙} = −0.9644 ± 0.0169
	a₃ = −0.2643			a₃ = −0.2485			a_{3 ⊙} = + 0.8481 ± 0.0174
	a₄ = + 0.1311			a₄ = + 0.1083			a_{4 ⊙} = −0.3371 ± 0.0065

3D	−	8.534 ± 0.003 ± 0.036	4.85	−	6.037 ± 0.002 ± 0.025	4.40	−

Power	α = 0.1404 ± 0.0050	8.502 ± 0.006 ± 0.036	3.90	α = 0.1545 ± 0.0044	5.999 ± 0.004 ± 0.025	3.33	α_⊙ = 0.15027 ± 0.00006

Scaled solar	s₀ = 0.716 ± 0.042	8.498 ± 0.007 ± 0.036	4.38	s₀ = 0.598 ± 0.027	5.996 ± 0.004 ± 0.025	3.13	s_{0 ⊙} = 0.59045 ^d

Notes.

^(a)

The statistical and systematic uncertainties on the angular diameters are listed separately as ± σ_stat ± σ_syst.

^(b)

The linear limb darkening coefficients u are taken from Claret & Bloemen (2011).

^(c)

The four-parameter non linear limb darkening coefficients a₁...a₄ are taken from Claret & Bloemen (2011).

^(d)

The value of s₀ for the Sun is the average over the H band from the observed profile by Pierce et al. (1977).

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