Given that they’ve been around when our universe was still a few billion years old, are ancient globular star clusters the most likely part of our Milky Way galaxy to harbor advanced intelligent extraterrestrial life?
By: Ringo Bones
Even though the hypothesis has probably been worked out by a few science fiction authors during the last two centuries, it was in a recent press conference during the annual meeting of the American Astronomical Society back in January 6, 2016 that Dr. Rosanne DiStefano of the Harvard-Smithsonian Center for Astrophysics presented her team’s latest research findings indicating that we may one day find intelligent space-faring civilizations occupying star clusters at the edges of our own Milky Way galaxy. According to DiStefano, lead author of the study published from a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory states that: “A globular cluster might be the first place in which intelligent life is identified in our galaxy.”
These ancient globular star clusters are spherical in shape and can contain anywhere from hundreds of thousands to millions of individual stars. In fact, the oldest stars in the Milky Way galaxy can be found in these areas with a ripe old age of about 10-billion years old. By way of comparison, current data shows that the age of our universe is about 13.8-billion years and scientists believe that some stars in these ancient globular star clusters may have been already around since the birth of our galaxy. The data that determined the age of these ancient globular star clusters have previously played an essential role in helping astronomers pinpoint the center of the Milky Way and aid in determining the exact age of the universe.
The main factor that determines the possibility of carbon-based Earth-like life-forms occurring in a typical star system is its Goldilocks or habitable zone. This refers to a “just right” distance between a planet and its parent star which directly affects the average temperature and the planet’s ability to allow water in its liquid state to exist. Brighter more energetically burning stars produce a larger potential habitable zone than their smaller, fainter counterparts but brighter, larger, more energetically burning stars have a much shorter lifespan and the largest of them seldom last for more than 150-million years.
Habitable planets that could exist in these ancient globular star clusters would have to be huddled near dim red dwarf stars and this is critical because smaller orbits help protect these planets from the violent forces found in such a crowded galactic neighborhood – forces that could eventually push a small world out into cold interstellar space. DiStefano claims that once these planets do form, they can survive for long periods of time, even longer than the current age of the universe.
Some of these globular star clusters are packed to the brim and astronomers have estimated that some contain up to a million stars that span a combined distance of up to 100 light-years. To give you an idea of how dense that is, our Sun’s nearest neighboring star is close to 4 light-years away.
The main idea drawn by this research includes the high probability of the formation of potentially habitable worlds in a globular cluster due to the sheer volume of stars and that these worlds could survive for billions of years. This is important because complex life takes time to evolve and to develop the kind of intelligence needed to build and maintain a civilization – especially a space-faring one.