Pulsating chromosphere of classical Cepheids. Calcium infrared triplet and H$\alpha$ profile variations

V. Hocdé, N. Nardetto, S. Borgniet +10

It has been shown recently that the infrared emission of Cepheids, which is constant over the pulsation cycle, might be due to a pulsating shell of ionized gas of about 15\% of the…