GH Lib: A multi-periodic Mira, not an eclipsing binary

Siviero, Alessandro and Munari, Ulisse and Righetti, Gian Luigi and Graziani, Mauro (2016) GH Lib: A multi-periodic Mira, not an eclipsing binary. Information Bulletin on Variable Stars, 62 (6183). ISSN 1587-2440

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Abstract

Over the period 2012-2016 we have obtained accurate V and R band photometry and 3400-8000 Ang spectroscopy which show the poorly studied variable GH Lib to be a multi-periodic Mira and not an Algol-type eclipsing binary. The main pulsation periods are 157 and 1180 days, with amplitudes of 3.5 and 1.0 mag, respectively. The spectral type change from M2III at maximum to M7III at minimum. The intensity of Halpha and Hbeta emission lines in GH Lib is much larger than in normal Miras, suggesting that the region of Balmer line formation is located at a larger radius (more external atmospheric layers) as if mixed with and not deeply below the region where absorption by TiO molecules occurs.

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