The Tiny Star

A few light years into the future, people will make spaceships that can travel at the speed of light. It will be an incredible invention powered by the stars in the universe but one dead end trip for the astronauts and the spaceship. They will enter a solar system with the star in the center the size of an ant. This star will be at least 100,000,000 degrees. But how can something so tiny be so hot? Although it is so hot, it won't have enough light to power the spaceship and eventually they will run out of oxygen.