Studying the 285.2 nm MgI spectral line, for stellar models

M. P. A. MENDEZ; J. I. PERALTA; M. C. VIEYTES; D. M. MITNIK

La Serena

Congreso; Second Binational Meeting AAA-SOCHIAS; 2018

AAA-SOCHIAS

It is studied the improvement of the atmospheric model 1401 (Fontenla, J. M. et al. 2015, ApJ, 809, 15) by improving the atomic model of the neutral Magnesium.The atomic models are essential to compute the populations in full NLTE. In this case, changes in the Effective Collision Strength (ECS) parameters for electron impact excitation were made, to test influence in the synthetic spectrums of the Sun and the GJ 832 M star.Given the relevance of the spectral features formed by Mg I in the stellar spectrum of late type stars, and because there is a need to improve the Mg I atomic model mainly in the NUV range (eg. 283.5 nm inverted line), the populations of the Mg I atom were recalculated using the Solar-Stellar Radiation Physical Modeling (SSRPM) code using new atomic models:* The atomic model to be improved it has its ECS parameters calculated by the Seaton's formula (for allowed transitions) and the van Regemorter's formula (for forbidden transitions).* In the atomic model generated by us, the ECS parameters are calculated using Distorted-wave method.* A third atomic model was made uses the ECS calculated by the R-matrix method. This calculations are the newest found and were provided by Barklem et al. (2017, A&A 606, A11).For each one of the three atomic models, an atmospheric model with the same thermal structure (for each object) was generated. Then we computed each synthetic spectra to identify and compare the most relevant changes in the formation of Mg I spectral lines in relation to the original model (1401), and over the observations.