An array of planets with similarities to some in our solar system have been found around a nearby star by astronomers using the European Southern Observatory’s Very Large Telescope in Chile.The star, known as L 98-59, is 35 light-years away from Earth. There may be as many as five planets in orbit around it, including an ocean world, a potentially habitable planet and one of the lightest-ever exoplanets ever discovered. Exoplanets are those that orbit stars outside of our solar system. The research published Thursday in the journal Astronomy & Astrophysics.During these new observations of the system, astronomers determined that three of the planets include some type of water content. The two planets closest to the star are likely dry and rocky with just small amounts of water. These terrestrial planets, like Earth or Venus, are close enough to the star to be warmed by it.Meanwhile, the third planet’s mass could be 30% water. This suggests that it could be an ocean world, similar to some of the moons found across our solar system.
These three planets were first spotted by astronomers in 2019 using NASA’s planet-hunting TESS mission, or Transiting Exoplanet Survey Satellite. The space-based observer is able to detect exoplanets using the transit method, which measures the dip in light that occurs when a planet passes in front of its star. Astronomers have another method of finding exoplanets that is known as radial velocity, which calculates the wobble that occurs when orbiting planets create gravitational tugs on a host star. Measurements from the TESS mission were combined with the radial velocity measurements made using the Very Large Telescope to learn more about these planets.
In this case, it allowed astronomers to determine that the planet closest to the star is just half the mass of Venus — making it the lightest exoplanet ever detected using radial velocity. “This is a step forward in our ability to measure the masses of the smallest planets beyond the Solar System,” said María Rosa Zapatero Osorio, author of the new research and an astronomer at the Centre for Astrobiology in Madrid, Spain, in a statement. During their research, team members also discovered a fourth planet and the hint of a potential fifth planet that wasn’t captured in the previous data from TESS. That fifth planet may be at the right distance from the star to allow liquid water to form on the surface. This is known as the star’s habitable zone.
“The planet in the habitable zone may have an atmosphere that could protect and support life,” Zapatero Osorio said.This planetary system is an ideal target for NASA’s James Webb Space Telescope, scheduled to launch into orbit around Earth in October, as well as the European Southern Observatory’s Extremely Large Telescope set to begin observations from Chile in 2027.
Both may be able to peer into the atmospheres of these planets. This opens up the potential to discover biosignatures, or signs of life, outside of our planet.”This system announces what is to come,” said Olivier Demangeon, lead study author and a researcher at the Instituto de Astrofísica e Ciências do Espaço, University of Porto in Portugal, in a statement. “We, as a society, have been chasing terrestrial planets since the birth of astronomy, and now we are finally getting closer and closer to the detection of a terrestrial planet in the habitable zone of its star, of which we could study the atmosphere.”