The size of ABDorA from VLTI/AMBER interferometry

TL;DR

This study uses VLTI/AMBER interferometry to measure the radius of the PMS star ABDorA, providing insights into magnetic activity effects and refining the system's age estimate around 40-50 million years.

Contribution

First direct interferometric measurement of ABDorA's size, revealing magnetic activity effects and constraining the system's age using PMS evolutionary models.

Findings

Measured star radius: 0.96+/-0.06 Rsun.

Observed radius larger than model predictions, indicating magnetic activity influence.

Estimated system age: approximately 40-50 million years.

Abstract

The pre-main sequence (PMS) star ABDorA is the main component of the quadruple system ABDoradus. The precise determination of the mass and photometry of the close companion to ABDorA, ABDorC, has provided an important benchmark for calibration of theoretical evolutionary models of low-mass stars. The limiting factor to the precision of this calibration is the age of the system, as both the mass and luminosity of ABDorA and C are well monitored by other ongoing programs. In this paper we present VLTI/AMBER observations of ABDorA which provide a direct measurement of the size of this star, 0.96+/-0.06 Rsun. The latter estimate, combined with other fundamental parameters also measured for this star, allows a precise test of PMS evolutionary models using both H-R diagrams and mass-radius relationships. We have found that our radius measurement is larger than that predicted by the models, which we interpret as an evidence of the oversizing produced by the strong magnetic activity of ABDorA. Considering, at least partially, this magnetic effect, theoretical isochrones have been used to derive constraints to the age of ABDorA, favouring an age about 40-50 Myr for this system. Older ages are not completely excluded by our data.