Stellar process
The Horizontal Branch
After helium ignites, a low-mass star settles into a stable phase of quiet core helium burning, sitting on the horizontal branch of the colour–magnitude diagram at roughly constant luminosity. Stars crossing the instability strip here pulsate as RR Lyrae variables.
Stars, stages & concepts
Across stellar astrophysics
Knowledge connections
- Associated withThe Triple-Alpha Process
- Associated withThe Helium Flash
- Associated withThe Triple-Alpha Process
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.