# Pickering series

> English word · Proper noun

## Definitions
1. Three lines of singly ionized helium found, usually in absorption, in the spectra of hot stars, produced by transitions of an electron with principal quantum number n=4 state from a higher energy level.

## Etymology
Named after Edward Charles Pickering.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/pickering-series