First detection of the He I 10 830 Å emission in spectra of classical Cepheid X Cyg

V. V. Kovtyukh , S. M. Andrievsky (1) , S. A. Korotin

1 GEPI - Galaxies, Etoiles, Physique, Instrumentation

For the first time, we describe a detection of the emission in the infrared (IR) He I triplet at 10 830 Å in the classical Cepheid X Cyg. Emissions are clearly seen at phases approximately from 0.25 to 0.85. The IR redshifted He I emission is excited by shock wave in the uppermost layers of the star's envelope, in its falling layers. This is a first detection of the helium IR emission in the classical Cepheids.

Keywords: stars: atmospheres; stars: chromospheres; stars: variables: Cepheids

Domains: Sciences of the Universe [physics]

V. V. Kovtyukh, S. M. Andrievsky, S. A. Korotin. First detection of the He I 10 830 Å emission in spectra of classical Cepheid X Cyg. Monthly Notices of the Royal Astronomical Society: Letters, 2022, 517, pp.L143-L145. ⟨10.1093/mnrasl/slac130⟩. ⟨insu-03849367⟩