High-latitude supergiants: anomalies in the spectrum of LN Hya in 2010

TL;DR

This study analyzes high-resolution spectra of LN Hya from 2003-2011, revealing spectral anomalies and rapid atmospheric changes in 2010, indicating dynamic physical conditions in its upper atmosphere.

Contribution

First detailed spectral analysis of LN Hya's atmospheric anomalies and rapid changes in 2010 using high-resolution spectra over multiple years.

Findings

Detected radial velocity variations due to pulsations.

Observed asymmetric line profiles and emission features.

Recorded rapid spectral changes in 2010 indicating atmospheric dynamics.

Abstract

High-resolution echelle spectra taken with the 6-m telescope in 2003-2011 are used to study features of the optical spectrum and the velocity field in the atmosphere of the semiregular variable LN Hya in detail. The weak symmetric photospheric absorptions indicate radial velocity variations from night to night (by as much as 3 km/s), resulting from small pulsations. Peculiarities and profile variations were found for strong lines of FeI, FeII, BaII, SiII, etc. The profiles of these lines were asymmetric: their short-wave wings were extended and their cores were either split or distorted by emission. During the 2010 observing season, the position and depth of the Halpha absorption component, the intensities of the short and long-wave emission components, and the intensity ratio of the latter components varied from spectrum to spectrum. Weak emissions of neutral atoms (VI, MnI, CoI, NiI, FeI) appeared in the spectrum of June 1, 2010. All these spectral peculiarities, recorded for the first time, suggest that we have detected rapid changes in the physical conditions in the upper atmospheric layers of LN Hya in 2010.