Yellow Dwarfs: The Sun and Its Stellar Cousins

Yellow Dwarfs

Yellow dwarfs are G-type main-sequence stars, similar to the Sun. They have a mass between 0.8 and 1.2 solar masses, a radius similar to that of the Sun, and moderate luminosity. Their energy is mainly produced by the fusion of hydrogen (nuclear fusion of hydrogen into helium via the proton-proton chain) into helium in the core.

Yellow dwarfs have the following characteristics:

• Mass: 0.8 to 1.2 M☉
• Radius: 0.9 to 1.2 R☉
• Effective temperature: 5,200 to 6,000 K
• Main sequence lifetime: about 10 billion years

The internal structure of a yellow dwarf includes several distinct zones:

• Core: where nuclear fusion reactions occur
• Radiative zone: where energy is transported by radiation
• Convective zone: where energy is transported by convection
• Photosphere: the visible surface of the star
• Chromosphere and corona: outer stellar atmospheres

Stellar Evolution

During their lifetime, yellow dwarfs go through several phases:

1. Main sequence: stable hydrogen fusion in the core.
2. Giant phase: when the central hydrogen is exhausted, the star expands and becomes a red giant.
3. Final phase: loss of outer layers and formation of a white dwarf (star mainly composed of carbon and oxygen).

The Most Studied Yellow Dwarfs

• Sources: NASA – Stellar Data (new window), International Astronomical Union (new window).

• Source: International Astronomical Union – Stellar Classification (new window)