Irrgang, A. ; De Cat, P. ; Tkachenko, A. ; Deshpande, A. ; Moehler, S. ; Mugrauer, M. ; Janousch, D.

published in Proceedings of the Polish Astronomical Society, 5, pp. 145-150 (2017)

Abstract: The bright B3 III giant star 18 Peg turns out to be a slowly pulsating B star in a long period binary with a main-sequence star or a neutron star as companion. Given that it is one of the most evolved members of this class of massive pulsating stars, an accurate determination of the location of 18 Peg in the Hertzsprung-Russell (H-R) diagram would provide a lower limit on the width of the upper main sequence and hence would reveal information about the efficiency of the convective overshooting. We explain why long-term space-based observations are needed and how BRITE could play a crucial role in the gathering of the mandatory ingredients to test the models of the upper main sequence evolution.

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