JWST Discovers Coldest Exoplanet and Its Characteristics

TapTechNews August 3rd news, astronomers used the James Webb Space Telescope (JWST) to study a new super Jupiter planet and found that it is one of the coldest planets ever discovered outside the solar system by humans, and the relevant results have been published in Nature magazine.

This exoplanet is located in the three-body/three-star system Persian 7 (Epsilon Indi) about 12 light-years away from the earth, and is named EpsIndAb, with a mass about six times that of Jupiter.

This planet has a highly elliptical or flat orbit. The distance from its parent star at the perihelion is about 20 times the distance between the earth and the sun, while at the aphelion, the distance from its parent star is equivalent to 50 times the average distance between the earth and the sun.

In simple terms, the orbital distance of this planet around its red dwarf parent star is similar to the distance between Neptune and the sun. So its surface temperature is about 0 degrees Celsius, and it takes about 200 Earth years to orbit its star. JWST now uses its sensitive infrared instrument (MIRI) to image this exoplanet.

For this kind of exoplanet, direct imaging is definitely an extremely difficult task. Before this, only dozens of exoplanets could be directly imaged (by space telescopes or ground observatories), and it is one of the latest. Previously imaged exoplanets are often very young and hot. Cold planets like EpsilonIndiAb have a very weak presence. Most of them only emit mid-infrared light and are not easy to discover, but Webb with infrared imaging ability is quite good at capturing such planets.

This planet has a higher temperature and mass than Jupiter, but is more like Jupiter than any planet photographed so far, orbiting the K-type star EpsilonIndiA, which is the main star of the three-star system and has about the same age as the sun but a slightly lower temperature.

This is the first time that a powerful space telescope has been able to image an exoplanet that has not been imaged on the ground before. Indian εAb is also the coldest exoplanet that JWST can currently study.

When we realized that we had photographed this new planet, we were very excited, said Elizabeth Matthews, a researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany, and the lead author of the study, in a statement.

The parent star of this planet is a red dwarf star named EpsIndA, which has two stellar companions, and both are brown dwarfs (failed stars. Although the formation process is like a star, it cannot gather enough mass and therefore cannot trigger the nuclear fusion process called main sequence star).

Although direct imaging is difficult, the research team did not give up easily. The team used Webb MIRI's coronagraph (TapTechNews note: This is a blocker that blocks starlight, basically equivalent to simulating an eclipse) to observe it.

We found a signal in the data that didn't match the expected exoplanet, Matthews said. EpsIndAb appeared as a spot of light in the MIRI image, not at the predicted position, but this planet still seems to be a giant planet.

In order to confirm this, the team needs to re-examine the same area using the Very Large Telescope (VLT). If the scientists find a faint object and the signal is finally confirmed to come from EpsIndA, then it means that the object is exactly at the right position.

Matthews and colleagues also tried to use MIRI data to explore the atmospheric structure of EpsIndAb. They found that this super Jupiter seems to be filled with various heavy elements, especially carbon, including molecules such as methane, carbon dioxide, and carbon monoxide, which often exist in gas giant planets.

For this, one explanation is that the atmosphere of this planet is cloudy, but all these mean that the research team needs more data to understand EpsIndAb. The team plans to obtain the spectral data of EpsIndAb to provide detailed fingerprints of the chemical composition and general climate of the super Jupiter.

Matthews concluded: In the long run, we hope to observe other nearby planetary systems to look for cold gas giants that may have been missed. Such investigations will help to better understand the formation and evolution of gas planets.