VILLANOVA, Pa. – Two Villanova University astrophysicists are part of an international team of researchers that has discovered a candidate super-Earth planet orbiting the second nearest star system to the Earth. Announcement of the new find was made Nov. 15 in the academic journal Nature.
Members of “The Red Dots Project,” a European-led scientific collaboration with researchers representing 33 universities and scientific institutions, Edward Guinan, PhD and Scott Engle, PhD—both professors in Villanova’s Department of Astrophysics and Planetary Sciences—were two of the researchers and co-authors of the paper, “A candidate super-Earth planet orbiting near the snow line of Barnard’s Star.” A red dwarf star, Barnard’s Star at about six light years from us, is the closest single star to the Sun and second only to the Alpha Centauri triple stellar system.
The planet candidate, named Barnard’s Star b (or GJ 699 b) is a cold super-Earth with mass just over three times the Earth’s mass orbiting the red dwarf star every 233 days about the same distance that Mercury orbits the Sun but near this dim star’s snow line. In the absence of an atmosphere, Barnard’s star b is likely to have a temperature of about -170 degrees centigrade making it unlikely that the planet can sustain liquid water on its surface. However, the higher mass of the super-earth could, according to Guinan, result in higher internal temperatures and geothermal activity than the Earth, which might warm the planet (in niches of the planet near thermal vents) making it possible to sustain life.
The international team of astronomers led by Ignasi Ribas of the Institute of Space Studies of Catalonia (IEEC), and Institute of Space Sciences (ICE, CSIC), based its analysis on 18 years of observations combined with new observations.
As participants in the Red Dots research project, Guinan and Engle have carried out high precision photometry of Barnard’s star (as well as dozens of other stars) for the past three years using robotic telescopes in Arizona. The pair have obtained photometry of Barnard’s Star for the past 15 years, the data from which was added to the Red Dots analysis.
“Barnard’s Star has been on our radar for a long time,” Guinan said. “In 2003 it became a founding star member of the Villanova ‘Living with a Red Dwarf’ program that has been sponsored by the National Science Foundation/National Aeronautical and Space Administration (NASA).
“The most significant aspects of the discovery of Barnard’s star b is that it demonstrates planets aren’t only found at vast distances from the solar system, but within the Sun’s local stellar neighborhood,” Engle noted. “Also, Barnard’s Star is about twice as old as the Sun – about 9 billion years old compared to 4.6 billion years for the Sun. The universe has been producing potentially habitable planets far longer than the Sun has existed.”
Guinan agreed, adding that it is possible that the majority of stars cooler than our Sun may host planets.
“What is significant about this planet is that its angular separation from its host is large enough that it may be able to be imaged by NASA’s Webb Space Telescope as well as by the next generation of extremely large ground-based telescopes,” he added. These observations may reveal if the Barnard Star b has an atmosphere and details about its composition.
“Since the star and its planet are so nearby, they will be natural targets for future instruments like the James Webb Space Telescope and the velocity measures from the ground will continue to search for any other planets orbiting the star,” Engle agreed.
Both Guinan and Engle are delighted to be part of the team that discovered Barnard’s star b.
“It has been very exciting to be part of this international collaboration to search for exoplanets. I have been very lucky to have witnessed the discovery of now thousands of exoplanets over the past 20 years and am grateful that I have been able to make a contribution to the research,” Guinan said.
Engle agreed. “It’s been great. The team has done fantastic work and we’re very happy that our data could be of such use.”
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