For the first time, citizen scientists discover a five-exoplanet system with super-earths, using Kepler data.
Exoplanet Explorers is a project where citizen scientists discover different exoplanets. Thus, studying the physical features of these planets, such as their atmosphere, density, and chemistry.
However, this is the first time that a multi-planet system has been discovered entirely through crowdsourcing.
Scientists call this system K2-138. The five planets are all part of the same star system. The K2-138 lies about 620 light-years from Earth, in the constellation Aquarius. They classify all of these planets as super-Earths.
The planets in the K2-138 system are about two to three times larger than our planet. They orbit their parent star very closely, meaning they are all likely extremely hot.
All five planets of K2-138 also appear to be in “resonance” — a configuration in which the size of each planet’s orbit is a ratio of other planets’ orbits. That suggests the planets all formed together in a smooth, rotating disc before moving closer in toward the star over millions of years.
UC Santa Cruz astronomer Ian Crossfield and Caltech staff scientist Jessie Christiansen launched the Exoplanet Explorers project on the online platform Zooniverse in 2017. The project gives volunteers the opportunity to investigate data from NASA’s Kepler space telescope for signs of exoplanets.
“People anywhere can log on and learn what real signals from exoplanets look like, and then look through actual data collected from the Kepler telescope to vote on whether or not to classify a given signal as a transit, or just noise,” said Christiansen in a Caltech news release.
“We have each potential transit signal looked at by a minimum of 10 people, and each needs a minimum of 90 percent of ‘yes’ votes to be considered for further characterization,” she added.
In April 2017, scientists featured the Exoplanet Explorers project on the Australia Broadcasting Corporation (ABC) program Stargazing Live. On the final night of the three-day event, citizen scientists uncovered K2-138.
The K2 data was mostly light curves, showing the intensity of light from individual stars. Scientists indicate a possible transit across the star’s face by an object if there was a dip in the intensity.
Thumbnail credit: Kepler K2-138 System (Artist’s Concept) Credit: NASA/JPL-Caltech