Astronomers have discovered an Earth-sized exoplanet, or world outside our solar system, that may be covered in volcanoes. Dubbed LP 791-18 d, the planet can experience volcanic eruptions as often as Jupiter’s moon Io, the most volcanically active body in our solar system.
They discovered and studied the planet using data from NASA’s TESS (Transiting Exoplanet Survey Satellite) and the retired Spitzer Space Telescope, as well as an array of ground-based observatories.
A paper on the planet — led by Merrin Peterson, a graduate student at the Trottier Institute for Exoplanet Research (iREx) based at the University of Montreal — appears in the May 17 issue of the journal Science. nature.
“LP 791-18 d is gradually closed, which means that the same side is constantly facing its star,” said Bjorn Beneke, co-author and iREx professor of astronomy who planned and supervised the study. “The day side is likely to be very hot on the surface of the liquid water. But the amount of volcanic activity that we suspect is happening across the planet could have preserved the atmosphere, which could allow the water to condense at night.”
LP 791-18 d orbits a small red dwarf star about 90 light-years away in the southern constellation Crater. The team estimates that it is slightly larger and larger than Earth.
Astronomers already knew about two other worlds in the system before this discovery, called LP 791-18 b and c. Inner planet B is about 20% larger than Earth. Exoplanet C is about 2.5 times the size of Earth and more than seven times its mass.
During each orbit, planets d and c pass close to each other. Each pass close to the more massive planet c results in a gravitational pull on planet d, which makes its orbit somewhat elliptical. In this elliptical path, Planet D deforms slightly each time it orbits the star. These deformations can create enough internal friction to greatly heat a planet’s interior and produce volcanic activity on its surface. Jupiter and some of its moons affect Io in a similar way.
Planet d lies at the inner edge of the habitable zone, the traditional range of distances from a star where scientists assume liquid water could exist on a planet’s surface. If the planet is geologically active as the research team believes, it can maintain an atmosphere. Temperatures can get low enough on the night side of the planet for water to condense on the surface.
Planet C has already been approved for timekeeping on the James Webb Space Telescope, and the team believes that Planet D is also an exceptional candidate for atmospheric studies by the mission.
said co-author Jessie Christiansen, a research scientist at the NASA Institute for Extrasolar Science at Caltech in Pasadena. “In addition to potentially providing the atmosphere, these processes could yield materials that would otherwise sink and get stuck in the crust, including those we think are important to life, such as carbon.”
Spitzer’s observations of the system were among the last satellites collected before it was shut down in January 2020.
“It’s fascinating to read about continued discoveries and publications years after the Spitzer mission ended,” said Joseph Hunt, Spitzer project manager at NASA’s Jet Propulsion Laboratory in Southern California. “This really shows the success of our first-rate engineers and scientists. Together, they built not only a spacecraft but a data set that continues to be an asset to the astrophysics community.”
TESS is a NASA astrophysics mission led and operated by the Massachusetts Institute of Technology in Cambridge, Massachusetts, and operated by NASA’s Goddard Space Flight Center. Additional partners include Northrop Grumman of Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; Center for Astrophysics | Harvard and Smithsonian in Cambridge, Massachusetts; Lincoln Laboratory at the Massachusetts Institute of Technology. and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories from around the world are participating in the expedition.
All of the science data collected by Spitzer during its lifetime is publicly available via the Spitzer Data Archive, located in the Infrared Science Archive at IPAC at Caltech in Pasadena, California. NASA’s Jet Propulsion Laboratory, a division of Caltech, managed Spitzer mission operations for the agency’s Science Mission Directorate in Washington. Science operations were conducted at the Spitzer Science Center at Caltech’s IPAC. Spacecraft operations took place at Lockheed Martin Space in Littleton, Colorado.