Scientists conducting an international study of the deep cosmos discovered the planet orbiting a star with a long-period orbit, a new study reveals.
And the astronomers discovered a planet that not only took 120 days to orbit its star, but circles a hot Jupiter-like star for 20 years. The new planet, named TRAPPIST-1b, is dubbed a “habitable zone planet,” a star outside our solar system that should have water. It’s also the first planet they found orbiting a star with a long-period orbit.
The finding adds new weight to the belief that planets outside our solar system are the most likely bet for alien life to exist.
For the year-long study, about 55 astronomers living in three continents spent about five hours a day attending astronomy events, sometimes being forced to sleep in a field because there was no room at the library. They met at the University of Chile’s McElhinney Observatory to see if they could discover as many new planets as possible while hunting for a powerful force of dark energy that explains the accelerating expansion of the universe.
Between June 2015 and March 2016, they found seven planets, according to data published this week in the science journal Nature. Many of the planets found during the study orbited stars that were closer in or fewer than 4.6 light-years away. The vast majority were like Earth in size and orbit.
The eight new planets all orbit within a wide region beyond our solar system. That part of the sky in the constellation Taurus is filled with planets, and the astronomers calculated that all of the stars in the region, more than 800 stars, may harbor another earth in their orbit.
The researchers also found that the planets rotate more slowly than our sun, and also suggested that the planets could not have been formed as they appeared to do from our planet.
Study co-author Thomas Pike of the Universidad San Juan de Dios in Chile said in a statement that not only did they find “a pattern of small eccentricities in the planetary orbits” that may “correlate with random process” and “could easily explain these properties.”
“The main observation is that the planets rotate significantly slower than our sun,” Pike said. “So they could not have formed in this way from what we see in this study.”
He said the fact that the planets are all in the same region makes them most likely to be planets or star systems.
The ancient cosmos also provided the scientists with clues that they might have found the gravitationally pulling force, or dark energy, underlying the movement of the universe.
The gravitational pull of the stars, called gravitational lensing, allows light from planets orbiting the stars to be refracted by the way the light from the two stars moves relative to each other, reaching our telescopes and explaining how the universe expanded. The strength of this effect on the light and the planets’ distance from each other allowed astronomers to figure out the eccentricity.
An eccentricity of 1.2 has been widely used to calculate a planet’s eccentricity, in order to compare with the chances that its path is warped by a passing planet. The average elliptical orbit of a planet orbiting a star is a 1.2. The study found that the TRAPPIST-1b planet’s eccentricity was 1.5, while TRAPPIST-1c, another new planet, has a 0.9 eccentricity.
“It is quite incredible,” co-author Victoria Kaspi of the University of California, Los Angeles, said in a statement. “The results are pretty surprising given that TRAPPIST-1b is so young, and that it orbits the second closest young star system to our solar system.”
Kaspi said the researchers thought their study would not provide enough detail to challenge conventional thinking that evolved after the discovery of the Hubble Space Telescope. The Hubble photos showed galaxies that were even older than that of our own galaxy. That led to the hypothesis that most galaxies and stars are some form of nuclear fusion, and that their gravity puts them in elliptical, or spherical, orbits.
“By adding close-ups from the new observations, the results challenge the theories of [galactic] gravity and dark energy that emerged after our mission to Hubble,” she said.