The He I 10 830 Å line: Radiative transfer and differential illumination effects Andrés Vicente Arévalo, Jiří Štěpán, Tanausú del Pino Alemán and María Jesús Martínez González A&A, 675 (2023) A45 Published online: 30 June 2023 DOI: 10.1051/0004-6361/202346089