Query : 2016A&A...591A.124K

2016A&A...591A.124K - Astronomy and Astrophysics, volume 591A, 124-124 (2016/7-1)

Absolute parameters for AI Phoenicis using WASP photometry.


Abstract (from CDS):

Context. AI Phe is a double-lined, detached eclipsing binary, in which a K-type sub-giant star totally eclipses its main-sequence companion every 24.6-days. This configuration makes AI Phe ideal for testing stellar evolutionary models. Difficulties in obtaining a complete lightcurve mean the precision of existing radii measurements could be improved.
Aims. Our aim is to improve the precision of the radius measurements for the stars in AI Phe using high-precision photometry from the Wide Angle Search for Planets (WASP), and use these improved radius measurements together with estimates of the masses, temperatures and composition of the stars to place constraints on the mixing length, helium abundance and age of the system.
Methods. A best-fitEBOP model is used to obtain lightcurve parameters, with their standard errors calculated using a prayer-bead algorithm. These were combined with previously published spectroscopic orbit results, to obtain masses and radii. A Bayesian method is used to estimate the age of the system for model grids with different mixing lengths and helium abundances.
Results. The radii are found to be R1=1.835±0.014R, R2=2.912±0.014R and the masses M1=1.1973±0.0037M, M2=1.2473±0.0039M. From the best-fit stellar models we infer a mixing length of 1.78, a helium abundance of YAI=0.26 +0.02–0.01 and an age of 4.39±0.32Gyr. Times of primary minimum show the period of AI Phe is not constant. Currently, there are insufficient data to determine the cause of this variation.
Conclusions. Improved precision in the masses and radii have improved the age estimate, and allowed the mixing length and helium abundance to be constrained. The eccentricity is now the largest source of uncertainty in calculating the masses. Further work is needed to characterise the orbit of AI Phe. Obtaining more binaries with parameters measured to a similar level of precision would allow us to test for relationships between helium abundance and mixing length.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: solar-type - stars: evolution - stars: fundamental parameters - binaries: eclipsing

Errata: erratum vol. 620, art. C5 (2018)

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 V* AI Phe EB* 01 09 34.1924055096 -46 15 56.071719360   9.26 8.60     G3V 140 0
2 HD 294598 EB* 06 04 33.8024143104 -03 11 51.599883444   10.52 9.88     G0 37 0
3 V* IM Vir EB* 12 49 38.6982565560 -06 04 44.864911128   10.34 9.69   8.834 G5/6V 73 0
4 V* EF Aqr EB* 23 01 19.0925274336 -06 26 15.356891616   10.48 10.04   9.247 G1V 38 0

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