Star selection criteria
In lieu of additional data, it is probably safe to presume that life, at virtually all levels, and manifestations, exhibits a “Normal Distribution” across stellar class. Taking Sol/Earth as the only reference extant and applying the standard distribution we should find that stellar class “G5” is the center of our curve, and “M” class and “A” class as our extremes.
As stars become smaller and colder (progression of “M” class), the planets become tidally locked. While this doesn’t eliminate the probability of life, it will certainly affect the rate at which that life evolves. Thus even after 10’s of billions of years the life may not become advanced.
Conversely, as a star progresses toward class “A”, its life span shortens and any life developing will experience a shortened “evolution time”.
The advanced, nearly space faring species found on Earth took 4.6 billion years to evolve. A similar “track” should be presumed for all other planets until better information is available. It is said that the source of the Hill Template was visitors from Zeta Reticuli; Zeta(s) Reticuli are estimated at 3 billion years (7.1 max) which may help to establish a lower limit for evolution time.
Thus the fundamental criteria for star selection is;
- Stellar classification “F”, “G”, or “K”
- Main Sequence star
- 3 billion or more years old.
- Not a variable star
- Not a close binary
Many of the thousands of available stars are “disqualified” early due to their “type” (as differentiated from “class”). For the most part only type “V” (main sequence) stars are suitable, other types indicate a dying star; for instance, a type IV star is called a “Sub giant”. In a type IV star; its internal structures have collapsed, and the star actually shrinks a little. Over a short time the star enlarges and engulfs its inner planets. We don’t seem to have much data on the dying process…yet. For instance; how long does a star remain in the different states of “dying”? Could a star remain in the “Giant” state long enough for life to evolve to an advanced level?