Your My Hy-Vee account provides access to your history, allows you to print records, submit multiple prescriptions at once and more. Learn more. This healthy lifestyle program emphasizes eating for good health, weight loss and being physically active. Beginâ¢ is not a âdietâ- Beginâ¢ is a plan to help with lifelong wellness.
Given sufficient temperature and pressure, 4 hydrogen nuclei fuse to produce helium, at the same time giving off energy in the form of heat and light and other forms of radiation. This means that stars, with a few exceptions such as super-massive stars, last for many billions of years.
(1) When a star exhausts the hydrogen in its core, it becomes a giant or supergiant. The layer immediately above the core becomes hot enough to initiate the fusion of hydrogen into helium. The star now has THREE main layers: ( 1 1) Helium core (inner layer): Releases energy as it shrinks in radius. ( 2 2) Fusion shell: Releases energy as it fuses hydrogen into helium. ( 3 3) Hydrogen envelope (outer layer): Absorbs energy, and swells greatly in size.