Scientists don't just call a star "red" based on its appearance. They classify stars based on their spectral class, which is determined by the temperature of their surface. Here's how it breaks down:

* Red stars are classified as M-type stars. They are the coolest stars on the main sequence, with surface temperatures ranging from 2,400 to 3,700 Kelvin.

* Other types of stars can also appear reddish, depending on their age and composition. For example, some K-type stars (with surface temperatures between 3,700 and 5,200 Kelvin) can appear slightly reddish.

So, while we might see a star as "red," scientists are more precise and use the spectral classification system to describe its properties.

Here's a helpful table showing the spectral classes and their corresponding colors:

| Spectral Class | Temperature (Kelvin) | Color |

|---|---|---|

| O | > 30,000 | Blue |

| B | 10,000 - 30,000 | Blue-white |

| A | 7,500 - 10,000 | White |

| F | 6,000 - 7,500 | Yellow-white |

| G | 5,200 - 6,000 | Yellow |

| K | 3,700 - 5,200 | Orange |

| M | 2,400 - 3,700 | Red |

Remember, even though a star might appear red to the naked eye, it might not be a true "red star" in the scientific sense.