The Webb Space Telescope has discovered a super-Jovian planet orbiting a neighboring star, and its orbit is extraordinary.
The planet is about the same diameter as Jupiter, but has six times its mass. Its atmosphere is also rich in hydrogen, like Jupiter’s.
One big difference: It takes this planet more than a century, possibly as long as 250 years, to go around its star. It is 15 times farther from its star than Earth is from the Sun.
Scientists had long suspected that a large planet was orbiting this star that is located 12 light-years away, but they did not think that it was so large or that it was so far from its star. A light-year is equivalent to 9.28 trillion kilometers (5.8 trillion miles). These new observations show that the planet orbits the star Epsilon Indi A, which is part of a three-star system.
An international team led by Elisabeth Matthews of the Max Planck Institute for Astronomy in Germany collected the images last year and published them Wednesday in the journal Nature.
Astronomers directly observed this incredibly old and cold gas giant—a rare and complicated feat—by masking the star by using a special shading device on the Webb telescope. By blocking the star’s light, the planet stood out as a point of infrared light.
According to Matthews, the planet and star are 3.5 billion years old, or 1 billion years younger than our own solar system, but they are still considered older and brighter than expected.
The star is so close to our solar system and is so bright that it is visible to the naked eye in the Southern Hemisphere.
But nothing guarantees that there is life on Superjupiter.
“This is a gas giant with no hard surface or oceans of liquid water,” Matthews explained in an email.
According to Matthews, this solar system is unlikely to host more gas giants, but there could be small rocky worlds.
Jupiter-like planets can help scientists understand “how these planets evolve over gigayear timescales,” he says.
The first planets outside our solar system — called exoplanets — were confirmed in the early 1990s. In mid-July, NASA counted 5,690 planets. The vast majority were detected by the transit method, in which a fleeting decrease in starlight, which repeats at regular intervals, indicates the existence of an orbiting planet.
Space and ground-based telescopes are on the hunt for more planets, especially those that might be Earth-like.
Launched in 2021, the Webb telescope of NASA and the European Space Agency is the largest and most powerful astronomical observatory ever placed in space.