TY CONF TI A nature of the X-ray and optical emission from gamma Cassiopeia stars KW stars: general KW emission-line KW Be; X-rays: stars JO Modern astronomy: from the Early Universe to exoplanets and black holes AU Kholtygin, A.. AU Yakunin, I.. AU Ryspaeva, E.. AU Mokshin, D.. PY 2024 PB Special Astrophysical Observatory of the Russian Academy of Sciences