CaII Infrared triplet line models in Classical T Tauri stars

TL;DR

This paper models the formation of CaII infrared triplet lines in the magnetospheric flows of Classical T Tauri stars, explaining observed variability through changes in accretion rates and conditions.

Contribution

It provides a comprehensive grid of models for CaII triplet line formation in CTTS magnetospheres and applies them to interpret multi-epoch observations of DI Cep.

Findings

Lines form in magnetospheric infall

Variability explained by accretion rate changes

Models match observed line variability

Abstract

We study the formation of the calcium II infrared triplet lines 8498\AA, 8542\AA and 8662\AA, in the accreting magnetospheric flows of Classical T Tauri stars (CTTS), and present a grid of models for a large range of magnetospheric conditions. We apply our models to the interpretation of multi epoch observations of the CTTS DI Cep. We find that these lines form in the magnetospheric infall and that the variability of the CaII triplet lines in DI Cep can be explained in the context of changes in the mass accretion rate/temperature of the accretion column gas.