The helium line is very strong, far too strong.
In contrast, there are also helium-weak B-type stars with understrength helium lines and strong hydrogen spectra.
A strong helium line?
DAB: a hydrogen- and helium-rich white dwarf displaying neutral helium lines.
DAO: a hydrogen- and helium-rich white dwarf displaying ionized helium lines.
Cryogenic cooling of devices and material is usually achieved via the use of liquid nitrogen, liquid helium, or a cryocompressor (which uses high pressure helium lines).
This star displayed no lines of hydrogen in its spectrum, but strong helium lines as well as the presence of carbon and oxygen.
And the helium lines are up in the violet.
Yet all Type I supernova are distinguished by their lack of hydrogen absorption lines, and Type Ic also lack the presence of helium lines.
The H-zeta line (transition 8-2) is similarly mixed in with a neutral helium line seen in hot stars.
