2017A&A...597A.137K


Query : 2017A&A...597A.137K

2017A&A...597A.137K - Astronomy and Astrophysics, volume 597A, 137-137 (2017/1-1)

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

KERVELLA P., BIGOT L., GALLENNE A. and THEVENIN F.

Abstract (from CDS):

The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars α Centauri A (G2V) and B (K1V) with the VLTI/PIONIER optical interferometer. The combination of four configurations of the VLTI enable us to measure simultaneously the limb darkened angular diameter θLD and the limb darkening parameters of the two solar-type stars in the near-infrared H band (λ=1.65µm). We obtain photospheric angular diameters of θLD(A)=8.502±0.038mas (0.43%) and θLD(B)=5.999±0.025mas (0.42%), through the adjustment of a power law limb darkening model. We find H band power law exponents of α(A)=0.1404±0.0050 (3.6%) and α(B)=0.1545±0.0044 (2.8%), which closely bracket the observed solar value (α=0.15027). Combined with the parallax π=747.17±0.61mas previously determined, we derive linear radii of RA=1.2234±0.0053R (0.43%) and RB=0.8632±0.0037R (0.43%). The power law exponents that we derive for the two stars indicate a significantly weaker limb darkening than predicted by both 1D and 3D stellar atmosphere models. As this discrepancy is also observed on the near-infrared limb darkening profile of the Sun, an improvement of the calibration of stellar atmosphere models is clearly needed. The reported PIONIER visibility measurements of α Cen A and B provide a robust basis to validate the future evolutions of these models.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: individual: Alpha Centauri - techniques: interferometric - stars: solar-type - stars: fundamental parameters - binaries: visual

VizieR on-line data: <Available at CDS (J/A+A/597/A137): list.dat oifits/*>

Simbad objects: 14

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Number of rows : 14
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 HD 24035 SB* 03 43 42.5926451400 -72 36 32.798908692 9.70 9.74 8.51     K2:IIICN2Ba3CH4C21- 48 0
2 * 75 Cnc SB* 09 08 47.3310550733 +26 37 44.817238087   6.62 5.95 5.5   G5IV-V 133 0
3 * 2 Boo * 13 41 02.3464437048 +22 29 44.773950840   6.59 5.58     K0III 61 0
4 HD 123612 * 14 08 15.8599574352 +24 18 54.180012276   8.040 6.544     K5III 19 0
5 * d Boo SB* 14 10 23.9334932664 +25 05 30.037020972 5.44 5.37 4.83 4.39 4.10 F8V 167 0
6 HD 125728 * 14 20 45.0834800616 +26 04 31.900480428   7.718 6.787     G8II 31 0
7 NAME Proxima Centauri Er* 14 29 42.9461331854 -62 40 46.164680672 14.21 12.95 11.13 9.45 7.41 M5.5Ve 1144 0
8 HD 127753 V* 14 35 08.8059011688 -56 33 45.513566532   8.92 7.08     K5III 28 0
9 HD 128402 * 14 36 06.8726160960 +23 15 01.297175688 8.320 7.420 6.370     K0 23 0
10 * alf Cen ** 14 39 29.71993 -60 49 55.9990   0.4 -0.1     G2V+K1V 890 0
11 * alf Cen B PM* 14 39 35.06311 -60 50 15.0992 2.89 2.21 1.33     K1V 966 1
12 * alf Cen A SB* 14 39 36.49400 -60 50 02.3737 0.96 0.72 0.01     G2V 1208 0
13 HD 130948 BY* 14 50 15.8109853464 +23 54 42.634220112   6.456 5.867     F9IV-V 265 0
14 HD 133869 * 15 09 40.1324076312 -61 29 13.499798280   9.80 7.97     K3III 13 0

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2022.08.15-15:40:30

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