Red Dwarfs:
* Fuse hydrogen: These stars are small and cool, but they still have enough mass to ignite nuclear fusion in their cores, converting hydrogen into helium. This process generates energy, making them true stars.
* Long lifespan: They burn their fuel very slowly, giving them incredibly long lifespans (trillions of years).
* Dim and red: They emit a faint red light due to their cool temperatures.
Brown Dwarfs:
* Failed stars: They lack the mass (less than 8% of the Sun's mass) needed to sustain hydrogen fusion in their cores.
* No sustained fusion: They may undergo brief periods of deuterium fusion (a heavier isotope of hydrogen) but this is not enough to maintain a stable star.
* Cool and dim: They are even cooler and dimmer than red dwarfs, often emitting mostly infrared radiation.
Here's a table summarizing the differences:
| Feature | Red Dwarf | Brown Dwarf |
|---|---|---|
| Nuclear Fusion | Yes, hydrogen | No sustained fusion, brief deuterium fusion |
| Lifespan | Trillions of years | Short, eventually cool down |
| Mass | 0.08 - 0.8 solar masses | Less than 0.08 solar masses |
| Luminosity | Faint red | Very dim, mostly infrared |
In essence: Red dwarfs are small, cool stars that are still "burning" hydrogen. Brown dwarfs are "failed stars" that never reached the mass required for sustained fusion.
