Some Stars Could Support as Many as 7 Habitable Planets
by Matt Williams | Universe Today
In recent decades, over 4,000 extrasolar planets have been confirmed beyond our Solar System. With so many planets available for study, astronomers have learned a great deal about the types of planets that exist out there and what kind of conditions are prevalent. For instance, they have been able to get a better idea of just how common habitable planets are (at least by our standards).
As it turns out, a surprisingly high number of planets out there could support life. That is the conclusion reached by a team of astronomers and planetary scientists who conducted a study of the possible sizes of habitable zones (HZ) based on stellar classification. After considering how many planets could stably orbit within them, they came to the conclusion that stars with no Jupiter-sized gas giants can have as many as seven habitable planets!
This study was led by Stephen Kane, a professor of astrobiology from the University of California, Riverside (UC Riverside). He was joined by researchers from UC Berkeley, the University of Southern Queensland, the University of Hawaii, the California Institute of Technology (Caltech), the Caltech Infrared Processing and Analysis Center (IPAC), and the SETI Institute’s Carl Sagan Center for the Study of Life in the Universe.
The study was inspired by Kane’s own research of the TRAPPIST-1 star system, a nearby M-type (red dwarf) with no less than seven rocky planets (three of which orbit within the star’s HZ). This discovery, combined with the many rocky planets discovered around nearby red dwarf stars in recent years, has led astronomers to ponder just how many potentially habitable planets a star can host.
“This made me wonder about the maximum number of habitable planets it’s possible for a star to have, and why our star only has one,” as Kane explained in a UC Riverside News story. “It didn’t seem fair!” For the sake of their study, Kane and his colleagues created a model system in which they accounted for stars of various spectral classifications and planets of various sizes and orbits.