Scientists searching for
habitable planets beyond Earth shouldn’t overlook F-type stars in favor of
their more abundant, smaller and cooler cousins, according to new research from
University of Texas at Arlington physicists.
Stars fall into seven lettered
categories according to their surface temperature, but they also differ in
other factors such as mass, luminosity and abundance in the universe.
Scientists looking for habitable planets typically have focused on the less
massive end of the spectrum, where our own G-type sun as well as the even less
massive K and M-type stars reside.
F-types are the in the middle of
the scale, more massive and hotter than our sun. Their increased ultraviolet
radiation has been thought to be a limiting factor for sustaining life. In
addition, there just aren’t as many of them.
But, UT Arlington Physics
Professor Manfred Cuntz, contends: “F-type stars are not hopeless.”
Cuntz said: “There is a gap in
attention from the scientific community when it comes to knowledge about F-type
stars, and that is what our research is working to fill. It appears they may
indeed be a good place to look for habitable planets.”
Cuntz and UT Arlington Ph.D.
student Satoko Sato teamed with researchers from the University of Guanajuato
in Mexico for a new work published this week by the International Journal of
Astrobiology. They argue that since F-type stars have a wider habitability zone
– the area where conditions are right for general Earth-type planets to develop
and sustain life – they warrant additional consideration.
The researchers also explored
the potential limitations caused by UV radiation by estimating the potential
damage that carbon-based macromolecules necessary for life would sustain in
F-type stars’ habitable zones. To do that, they used DNA as an example and
compared estimates of DNA damage on planets in F-type star systems to the
damage that would be done on Earth by the sun.
The research included
calculations for several different types of F-type stars, at different points
in their evolution. It found encouraging results. In a few cases, the damage
estimates were similar to the damage on Earth, if Earth did not have an
atmosphere. The damage estimate was even less if an atmosphere on the planet in
the F-type system was assumed.
“Our study is a further
contribution toward the exploration of the exobiological suitability of stars
hotter and, by implication, more massive than the Sun … at least in the outer
portions of F-star habitable zones, UV radiation should not be viewed as an
insurmountable hindrance to the existence and evolution of life,” the study
The study is called
“Habitability around F-type Stars” and is available online here: http://journals.cambridge.org/action/displayIssue?jid=IJA&tab=firstview.
Co-authors from the University of Guanajuato were Cecilia Maria Guerra Olvera,
Dennis Jack and Klaus-Peter Schröder.
Pamela Jansma, dean of the UT
Arlington College of Science, said the collaboration between Sato and Cuntz is
representative of the research advances that can result from a strong
faculty-graduate student mentorship.
“Astrophysics as it relates to
habitable planets is an increasingly popular topic, and Dr. Cuntz and his
student have enriched that conversation by weaving elements of theoretical
biology and planetary science into their outstanding work,” Jansma said.
The new paper suggests that
further research be done that would include detailed chemical models of
planetary atmospheres, examples of specific star-planet systems with
observational data and cases of F-type stars that are members of binary or
About UT Arlington
The University of Texas at Arlington is a comprehensive research
institution and the second largest institution in The University of Texas
System. The Chronicle of Higher Education ranked UT Arlington as the
seventh fastest-growing public research university in 2013. U.S. News &
World Report ranks UT Arlington fifth in the nation for undergraduate
diversity. Visit www.uta.edu to learn more. Follow #UTAdna