Omega Centauri, Galaxy's Largest Globular Cluster, Is Too Busy For Life

"Despite the large number of stars concentrated in Omega Centauri's core, the prevalence of exoplanets remains somewhat unknown," said study lead-author Stephen Kane, an associate professor of planetary astrophysics in UCR's Department of Earth Sciences. "However, since this type of compact star cluster exists across the universe, it is an intriguing place to look for habitability."

Crowded Neighborhood

As it turns out, this may not be the case. Kane's team looked at 470,000 stars in the core of Omega Centauri's core and found out that they're too tightly-packed to have habitable planets.

The team calculated the extent of the Habitable Zone for each of these stars and discovered that it sits a mere 0.5 AU of the host star, which is half the distance between Earth and the sun. (1 AU, or astronomical unit, defines the average distance from us to the sun, established at about 150 million kilometers, or 93 million miles.)

At the same time, the core stars of Omega Centauri sit incredibly close to each other, snuggled at a distance of 0.16 light-years from one another. By comparison, the sun is 4.22 light-years away from its nearest neighbor, Alpha Centauri.

This means that the cluster's core stars have "a relatively high rate of stellar close encounters that would disrupt planetary orbits within the Habitable Zone of typical Omega Centauri stars," shows the new study.

"The rate at which stars gravitationally interact with each other would be too high to harbor stable habitable planets," explains study co-author Sarah Deveny, a graduate student at San Francisco State University in California.

While it may look like a dead end (literally), Omega Centauri actually opens up the horizon in the search for signs of alien life. If anything, it has shown that astronomers must turn to "globular clusters with lower encounter rates" among their stars, which "might lead to a higher probability of finding stable habitable planets," notes Deveny.