Solar core

This article is about the core of the Sun. For the core of stars in general, see Stellar core.
An illustration of the structure of the Sun

The core of the Sun is considered to extend from the center to about 0.2 of the solar radius (139,000 km; 86,000 mi).[1] It is the hottest part of the Sun and of the Solar System. It has a density of 150,000 kg/m3 (150 g/cm3) at the center, and a temperature of 15 million kelvins (15 million degrees Celsius; 27 million degrees Fahrenheit).[2]

The core is made of hot, dense plasma (ions and electrons), at a pressure estimated at 26.5 million gigapascals (3.84×1012 psi) at the center.[3] Due to fusion, the composition of the solar plasma drops from 68 to 70% hydrogen by mass at the outer core, to 34% hydrogen at the center.[4]

The core contains 34% of the Sun's mass, but only 3% of the Sun's volume, and it generates 99% of the fusion power of the Sun. There are two distinct reactions in which four hydrogen nuclei may eventually result in one helium nucleus: the proton–proton chain reaction – which is responsible for most of the Sun's released energy – and the CNO cycle.

  1. ^ García, Rafael A.; Turck-Chièze, Sylvaine; Jiménez-Reyes, Sebastian J.; et al. (15 June 2007). "Tracking Solar Gravity Modes: The Dynamics of the Solar Core". Science. 316 (5831): 1591–1593. Bibcode:2007Sci...316.1591G. doi:10.1126/science.1140598. ISSN 0036-8075. PMID 17478682. S2CID 35285705.
  2. ^ "NASA/Marshall Solar Physics". NASA.gov. Archived from the original on 2019-03-29. Retrieved 2015-07-09.
  3. ^ "Sun Fact Sheet". NASA Space Science Data Coordinated Archive.
  4. ^ E. Gary, Dale. "Solar System Astronomy Lecture 22". New Jersey Institute of Technology.