# planetary nebula

> emission nebula consisting of a shell of ionized gas ejected from a red giant

**Wikidata**: [Q13632](https://www.wikidata.org/wiki/Q13632)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Planetary_nebula)  
**Source**: https://4ort.xyz/entity/planetary-nebula


## References

1. Library of Congress
2. RAMEAU
3. Freebase Data Dumps. 2013
4. Integrated Authority File
5. YSO-Wikidata mapping project
6. National Library of Israel
7. KBpedia
8. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)