# DD Hydrae

> RR Lyrae variable star in the constellation Hydra

**Wikidata**: [Q92580670](https://www.wikidata.org/wiki/Q92580670)  
**Source**: https://4ort.xyz/entity/dd-hydrae


## References

1. SIMBAD
2. Gaia Data Release 3
3. Mid-infrared period-luminosity relations of RR Lyrae stars derived from the AllWISE Data Release
4. Probing the outer galactic halo with RR Lyrae from the Catalina surveys
5. Gaia Data Release 2
6. VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
7. Gaia Early Data Release 3
8. Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system
9. Kinematics of metal-poor stars in the Galaxy. II. Proper motions for a large nonkinematically selected sample
10. The luminosities and distance scales of type II Cepheid and RR Lyrae variables