how did it get the name?
The term H II is pronounced "H two" by astronomers. "H" is the chemical symbol for hydrogen, and "II" is the Roman numeral for 2.
H II region
The term H II is pronounced "H two" by astronomers. "H" is the chemical symbol for hydrogen, and "II" is the Roman numeral for 2.
where could be found hii emission nebula regions Sometimes several hundred light-years across, are often associated with giant molecular clouds what does this region mean? It is a region of interstellar atomic hydrogen that is ionized
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H II region [SEP] Terminology
The term H II is pronounced "H two" by astronomers. "H" is the chemical symbol for hydrogen, and "II" is the Roman numeral for 2. It is customary in astronomy to use the Roman numeral I for neutral atoms, II for singly-ionised—H II is H in other sciences—III for doubly-ionised, e.g. O III is O, etc. H II, or H, consists of free protons. An H I region is neutral atomic hydrogen, and a molecular cloud is molecular hydrogen, H. In spoken discussion with non-astronomers there is sometimes confusion between the identical spoken forms of "H II" and "H".