Note 429 — Chapter IX · HELIUM STARS WITH BRIGHT LINES.
Reading edition
Keeler, Astr. and Astrophysics, vol. xiii. p. 486. The helium line, λ 4472, is specially described. It is bright in the Orion nebula, dark in all Orion stars.
Reading edition
Keeler, Astr. and Astrophysics, vol. xiii. p. 486. The helium line, λ 4472, is specially described. It is bright in the Orion nebula, dark in all Orion stars.