Jul 24. () –
A paper explains that New images of the nearest super-Jupiter open a new window to exoplanet researchElisabeth Matthews, a researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany, is the lead author of the research article published in the journal ‘Nature’.
“To our surprise, the bright spot that appeared in our MIRI images did not match the position we expected for the planet,” Matthews said.Previous studies had correctly identified a planet in this system, but underestimated the mass and orbital separation of this super-Jupiter gas giant.“With the help of JWST, the team was able to clear things up.
This detection is quite unusual in several ways. It shows the first exoplanet imaged with JWST that had not been photographed from Earth and is much colder than the gas planets that JWST has studied so far. “image” means that the planet appears as a bright spot in images and therefore represents direct evidence. The transit and radial velocity methods are indirect evidence, as the planet only reveals itself through its mediated effect.
The planet orbits the primary component of the nearby triple star system Epsilon Indi, or Eps Ind for short. Astronomical labeling conventions assign the label Eps Ind A to that primary star, a red dwarf star slightly smaller and cooler than the Sun. To construct the planet’s name, a “b” is appended, resulting in the designation Eps Ind Ab.
New JWST data are consistent with a super-Jupiter with a mass six times that of Jupiter in the Solar SystemEps Ind Ab orbits its host star in an eccentric elliptical orbit whose maximum separation from Eps Ind A should be between 20 and 40 astronomical units. An astronomical unit is the average distance between Earth and the Sun, approximately 150 million kilometers. The new values differ considerably from previous studies, so the team decided to call it a “new” planet.
To date, only a few cold gas giant planets are known to orbit solar-age stars, and all of these have been inferred indirectly from radial velocity measurements. By obtaining images and spectra of the planets, astronomers can study their atmospheres and trace the evolution of planetary systems against computer models..
Studying planets in fully established planetary systems helps tie up loose ends related to the later stages of planetary evolution and refine our overall understanding of planet formation and evolution. The recent observations pave the way for the discovery of many more of these cold gas giant planets, which will allow astronomers to study a new class of exoplanets and compare them to the gas giants in the solar system.
Previous studies attempted to investigate a giant planet orbiting Eps Ind A by radial velocity measurements. However, extrapolation of a small part of the orbit led to incorrect conclusions about the properties of the planet. After all, Eps Ind Ab needs about 200 years to orbit its star. Observations over several years are insufficient to determine the orbit with high precision.
So Matthews’ team came up with a different approach. They wanted to take a picture of the known planet using a method commonly known as direct imaging. Since the host stars of exoplanets are so brightoutshine any other nearby objects. Normal cameras would be overwhelmed by the blinding starlight.
For this reason, the team used JWST’s Mid-Infrared Instrument (MIRI) camera equipped with a coronagraph. This light-blocking mask covers the star like an artificial eclipse. Another advantage is Eps Ind’s proximity to Earth, which is only 12 light-years away. The closer the star is to the star, the greater the separation between two objects that appears in an image, offering a better chance of mitigating interference from the host star. MIRI was the perfect choice because it observes in the thermal or mid-infrared range, where cool objects shine brightly.
This work is just a first step towards the characterization of Eps Ind Ab.”Our next goal is to obtain spectra that will give us a detailed fingerprint of the planet’s climate and chemical composition.“says Thomas Henning, director emeritus of the MPIA, co-principal investigator of the MIRI instrument and co-author of the underlying paper.
“In the long term, we hope to also observe other nearby planetary systems to search for cold gas giants that may have escaped detection.“Matthews says. “Such a study would provide a foundation for better understanding how gas planets form and evolve.”
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