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arXiv · 2411.05314

A simple model for spectroscopic analyses of active stars

T. Nordlander·M. Baratella·L. Spina·V. D'Orazi
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Abstract

Spectroscopic analyses of young late-type stars suffer from systematic inaccuracies, typically under-estimating metallicities but over-estimating abundances of certain elements including oxygen and barium. Effects are stronger in younger and cooler stars, and recent evidence specifically indicates a connection to the level of chromospheric activity. We present here a two-component spectroscopic model representing a non-magnetic baseline plus a magnetic spot, and analyse the resulting synthetic spectra of young solar analogues using a standard spectroscopic technique. For a moderately active star with solar parameters and chromospheric activity index log R'_HK = -4.3 (~100 Myr), we predict that [Fe/H] is underestimated by 0.06 dex while v_mic is overestimated by 0.2 km/s; for higher activity levels we predict effects as large as 0.2 dex and 0.7 km/s. Predictions are in agreement with literature data on solar twins, and indicate that the model is a plausible explanation to the observed effects. The model is simple enough that it can be included in spectroscopic packages with only changes to the underlying spectrum synthesis modules, if a log R'_HK value is provided.

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T. Nordlander, M. Baratella, L. Spina, V. D'Orazi. 2024-11-08. A simple model for spectroscopic analyses of active stars. https://arxiv.org/abs/2411.05314

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