Observation of the lambda 10830 helium line in R CrB at a 1978 pre-maximum phase.

Summary The lOS3O neutral helium lime has been observed in RCrS, on 1978 January 18, in a pre-maximum phase, at about one magnitude from the maximum light. It appears with a P Cygni profile: the emission line is associated with a very broad violet-displaced absorption line, representing a radial velocity of km/s. This line confirms the presence of helium in ROrS and states the physical conditions in high temperature and high density that prevail in the circunstellar gas cloud at the observation time. Ke words -- stars: R Coronae Sorealis -- stars: circunstellar shells.