The coldest stars are known as brown dwarfs. They are too small to sustain nuclear fusion in their cores, like regular stars do. This means they don't produce their own light and heat, but rather emit a faint glow from their internal heat.

The coldest brown dwarfs discovered so far have surface temperatures around 25 degrees Celsius (77 degrees Fahrenheit). This is about the same temperature as a comfortable room!

Keep in mind that even though they are "cold" compared to other stars, brown dwarfs are still much hotter than the Earth's surface.