- A source of something emits / produces / generates / provides that something
- A star is a source of light / light energy through nuclear reactions
- So, a star emits light through nuclear reactions

- A star emits light through nuclear reactions
- A star is a kind of celestial object / celestial body
- Hence, a star is a celestial body that emits light through nuclear reactions

- A star is a celestial body that emits light through nuclear reactions
- Astronomical is similar to celestial
- Therefore, a star is an astronomical body that emits light through nuclear reactions

Therefore, a star is an astronomical body that emits light through nuclear reactions
Q: A star is a large astronomical body that
Context:
- A star is a kind of celestial object / celestial body 
- A source of something emits / produces / generates / provides that something 
- Astronomical is similar to celestial 
- A star is a source of light / light energy through nuclear reactions