Class M Stars are the most common type of stars in the galaxy, composing about 76% of the main sequence stars in our region of the galaxy. They are the next category colder than a Class K Star, and burn red as a result. Class M stars come in a variety of sizes and specifications:
- M V Stars, also known as Red Dwarfs.
- Giant stars, Supergiants, and Hypergiants. See also Red Giant Star.
- Mira Variables
- Flare Stars
- The hottest of the Brown Dwarfs. (The less energetic of the Brown Dwarfs are Class T Stars, or arguably not even stars at all.)
Named stars of Class M
Game and Story Use
- One possible explanation for Dark Matter is that there's just a lot more dimly-radiating Red and Brown Dwarves out there than we think there are. See MACHOs and RAMBOs for more information.
- A starship might bumble across such a system without realizing it.
- Gliese 581 has several planets. A few, including Gliese 581c and Gliese 581d are believed to be in the Goldilocks Zone of the star. 581c is of the right mass, radius, and orbital distance to possibly support extremophile life, and 581d could potentially support more conventional earth-like life. They're only 20.3 light years from earth.
- Gliese 581g is also a candidate, although astronomers disagree over whether it exists.
- And if that Red Dwarf can support life, other Class M's could. And since M V stars are the most common type of star in our region of the galaxy, we could be looking at a densely populated universe. See Loads and loads of races and Fermi's Paradox for more ideas.
- If there are space plants on planets in orbit around a Class M Star, they will likely evolve to absorb the red and infrared light for photosynthesis. One prediction is that they might use a black pigment similar to melanin. See Non-Green Photosynthesizers for more ideas.
- Unlike earth plants, these would be very dark on infrared photography. See Red Edge for more information. It's noteworthy that one way to detect from a distance the likelihood of a planet (circling a Class M Star) having an active biosphere is to look for this. If a planet near a red star is reflecting very little red or infrared light, that's a good indicator that photosynthesis is happening there.
- Since Class M Stars are the most common type of star in the galaxy, whatever you establish about them in your campaign will have far-reaching effects. For example, if you decide that most Class M stars have planets near them where life can or has evolved, then you're saying that life is very common in the universe, and that billions of worlds in our galaxy will have native species. If instead you decide that water rarely occurs in the region of Class M stars, then your universe is likely to be an inhospitable one where resources and lifeforms are rare.