The reason a doubly ionized helium gas,He III,will not produce absorption lines in a stellar spectrum is that:
A) a doubly ionized helium atom is simply a helium nucleus stripped of all its electrons, so it cannot absorb visible photons.
B) the gas temperature on any star is always so high that electrons are excited beyond energy levels in the atoms from which visible photons can be absorbed.
C) doubly ionized helium is meaningless because neutral helium contains only one electron.
D) the gas temperature on star surfaces can never be hot enough to excite electrons in this atom to levels from which they will absorb visible photons.

Question

Quizplus · Accepted Answer

A doubly ionized helium atom, also known as a helium III ion, has lost both its electrons and is simply a helium nucleus. Without any electrons to absorb photons, it cannot produce absorption lines in a stellar spectrum.

The Reason a Doubly Ionized Helium Gas,He III,will Not Produce