Stellar parameters and seismological analysis of the star 18 Scorpii

¹ Department of AstronomyBeijing Normal University, 100875 Beijing, PR China
e-mail: litanda@hotmail.com
² Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing, PR China

Received: 17 February 2012
Accepted: 14 September 2012

Abstract

Aims. We constructed models of the structure and evolution of the stars including diffusion and extra-mixing caused by rotation to estimate stellar parameters of the solar twin 18 Scorpii.

Methods. Based on the classical observed features, we considered three additional constraints, i.e., lithium abundance log N(Li), rotational period P_rot^eq, and average large frequency separation ⟨△ν⟩, by combing stellar models with observations to determine stellar parameters and the possible evolutionary status of 18 Scorpii.

Results. More accurate results of mass and age were found by our model than in previous studies. We estimate that the mass and age of 18 Scorpii are 1.030 ± 0.010 M_⊙ and 3.66_-0.50^+0.44 Gyr, respectively. Moreover, the model gave better constraints of atmospheric features due to the accurate age estimation.

Conclusions. The consideration of lithium, rotational period, and the average large frequency separation may help us in obtaining more accurate parameters of the star. Our results indicate that 18 Scorpii is a solar twin slightly more massive and younger than the Sun.