Establishing the Best Conditions for Primordial Life

Astronomers and planetary scientists have for a long time known that various types of stars are very important in determining a planet or moon's chances of ever harboring life. The age of the star is also an immensely-important factor, mostly because young stars generate massive amounts of harmful radiations, which could easily strip the atmosphere off of any planet. Yellow dwarfs, such as the Sun, seem to harbor among the best conditions for developing life, as evidenced by our very own existence.

At this point, the Sun can easily be described as a middle-aged star. It has lived about half of its estimated life span, and still has about 5 billion years to burn before it finally collapses into a white dwarf. The amounts of radiation it emits constantly stops being dangerous a good distance away from our planet, which just happens to be at the correct distance form the star, dead square in the center of its habitable zone. These factors allowed for the atmosphere to form, which was a prerequisite for the development of any form of life, no matter how basic.

At this year's International Astronomical Union (IAU) XXVIIth General Assembly, to be held in Rio de Janeiro, Brazil, the factors that allow for the formation of basic life around stars will be among the most hotly debated topics. Biologists, geologists, physicists, astronomers, and astrobiologists will all pull their expertise together and assess objectively the chance that each type of exoplanet and moon has of harboring life, depending on their position around their respective stars, and the type of stars they orbit.

“The Sun does not seem like the perfect star for a system where life might arise. Although it is hard to argue with the Sun's ‘success’ as it so far is the only star known to host a planet with life, our studies indicate that the ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf’ with a longer lifetime than the Sun – about 20-40 billion years,” believes Villanova University professor of astronomy and astrophysics Edward Guinan.

“These stars, also called K stars, are stable stars with a habitable zone that remains in the same place for tens of billions of years. They are 10 times more numerous than the Sun, and may provide the best potential habitat for life in the long run. On the more speculative side we have also found indications that planets like Earth are also not necessarily the best suited for life to thrive,” the expert adds.

“Planets two to three times more massive than the Earth, with a higher gravity, can retain the atmosphere better. They may have a larger liquid iron core giving a stronger magnetic field that protects against the early onslaught of cosmic rays. Furthermore, a larger planet cools more slowly and maintains its magnetic protection. This kind of planet may be more likely to harbor life. I would not trade though – you can't argue with success,” Guinan concludes, quoted by ScienceDaily.