A K V Star is a star that's a little colder than our Sun, but still relatively close in size to our own. See Stellar Classification for more details. As it turns out, these Orange stars are are typically 0.5 to 0.8 times as massive as our sun, and have a surface temperature between 3,900 K and 5,200 K.
Our sun is a G V Star, and has a projected life span of about 10 billion years (we're a little less than half way through that span). K V Stars can maintain the Main Sequence for much longer, having an anticipated life span of 15 billion to 30 billion years. As such, K V Stars are important to SETI and the search for alien life in general. They have a much longer time for life to evolve on their planets, and thus a higher chance of that life achieving sentience and intelligence. See also HabStar.
The star is cooler than ours, but that doesn't mean life that evolves around it will like colder temperatures. Median temperature of a planet is more directly determined by proximity to it's star, and by atmospheric conditions.
Game and Story Use
- Life that evolves on planets in orbit around a K V star may be very earth-like. I mean, compared to crazy energy beings or silicon-based lifeforms. K V's are likely to have a large and stable Goldilocks zone.
- Given the long life-spans of such systems, they're a potential home for precursors or sufficiently advanced aliens.