2011A&A...526A..89P


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST02:18:31

2011A&A...526A..89P - Astronomy and Astrophysics, volume 526A, 89-89 (2011/2-1)

The fundamental parameters of the roAp star γ Equulei.

PERRAUT K., BRANDAO I., MOURARD D., CUNHA M., BERIO Ph., BONNEAU D., CHESNEAU O., CLAUSSE J.M., DELAA O., MARCOTTO A., ROUSSEL A., SPANG A., STEE P., TALLON-BOSC I., McALISTER H., TEN BRUMMELAAR T., STURMANN J., STURMANN L., TURNER N., FARRINGTON C. and GOLDFINGER P.J.

Abstract (from CDS):

A precise comparison of the predicted and observed locations of stars in the H-R diagram is needed when testing stellar interior theoretical models. For doing this, one must rely on accurate, observed stellar fundamental parameters (mass, radius, luminosity, and abundances). We determine the angular diameter of the rapidly oscillating Ap star, γ Equ, and derive its fundamental parameters from this value. We observed γ Equ with the visible spectro-interferometer VEGA installed on the optical CHARA interferometric array, and derived both the uniform-disk angular diameter and the limb-darkened diameter from the calibrated squared visibility. We then determined the luminosity and the effective temperature of the star from the whole energy flux distribution, the parallax, and the angular diameter. We obtained a limb-darkened angular diameter of 0.564±0.017mas and deduced a radius of R=2.20±0.12R. Without considering the multiple nature of the system, we derived a bolometric flux of (3.12±0.21)x10–7erg/cm2/s and an effective temperature of 7364±235K, which is below the previously determined effective temperature. Under the same conditions we found a luminosity of L=12.8±1.4L. When the contribution of the closest companion to the bolometric flux is considered, we found that the effective temperature and luminosity of the primary star can reach ∼100K and ∼0.8L lower than the values mentioned above. For the first time, and thanks to the unique capabilities of VEGA, we managed to constrain the angular diameter of a star as small as 0.564mas with an accuracy of about 3% and to derive its fundamental parameters. In particular the new values of the radius and effective temperature should bring further constraints on the asteroseismic modeling of the star.

Abstract Copyright:

Journal keyword(s): methods: observational - techniques: high angular resolution - techniques: interferometric - stars: individual: γ Equ - stars: fundamental parameters

Errata: + corrigendum vol. 532, p. C1

Simbad objects: 4

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Number of rows : 4

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * alf Cir a2* 14 42 30.4195804 -64 58 30.493451 3.55 3.43 3.19 2.96 2.86 A7VpSrCrEu 329 0
2 * bet CrB a2* 15 27 49.7315305 +29 06 20.522375 4.08 3.97 3.68 3.50 3.45 F2VpSrCrEuSi 653 0
3 * eps Del V* 20 33 12.7719198 +11 18 11.741187 3.43 3.90 4.03 4.05 4.18 B6IV 138 0
4 * gam Equ a2* 21 10 20.5001160337 +10 07 53.682085548 5.03 4.94 4.68 4.43 4.32 A9VpSrCrEu 513 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-02:18:31

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