Astronomers Webb’s MIRI (Mid-Infrared Instrument) The image was taken of Epsilon Indi Ab, a gas giant several times the mass of Jupiter, located about 12 light years from Earth.
This image of Epsilon Indi Ab was taken with a coronagraph on Webb’s MIRI instrument. Image courtesy NASA / ESA / CSA / Webb / STScI / E. Matthews, Max Planck Institute for Astronomy.
Of the 25 planets that have been directly imaged to date, all are less than 500 million years old, and all but six are less than 100 million years old.
The newly imaged planet orbits Epsilon Indi A (HD 209100, HIP 108870), a K5V type star that is roughly the age of the Sun (3.7 to 5.7 billion years).
“Previous observations of this system have been more indirect measurements of the star, which gave us advance knowledge that there is likely to be a giant planet in the system tugging at the star,” said Dr Caroline Morley, an astronomer at the University of Texas at Austin.
“That’s why our team chose this system as our first observational system at Webb.”
“This discovery is fascinating because the planet is very similar to Jupiter – it’s a little warmer and more massive, but it’s more similar to Jupiter than any other planet imaged so far,” said Dr Elizabeth Matthews, astronomer at the Max Planck Institute for Astronomy.
“The cold planet is very dark and most of its radiation is in the mid-infrared. Webb is ideal for mid-infrared imaging, but it’s very difficult to do from the ground.”
“We also needed good spatial resolution to distinguish planets from stars in the images, and the large Webb mirror helps a lot in this regard.”
Epsilon Indi Ab is one of the coolest exoplanets ever directly detected, with an estimated temperature of 2 degrees Celsius (35 degrees Fahrenheit). This makes it the coolest planet ever imaged outside the solar system, and cooler than all but one free-floating brown dwarf.
The planet is only about 100 degrees Celsius (180 degrees Fahrenheit) warmer than the gas giants in our solar system.
This provides astronomers with a rare opportunity to study the atmospheric composition of a true solar system analogue.
“Astronomers have imagined there could be planets in this system for decades, and fictional planets orbiting Epsilon Indi have been the setting for Star Trek episodes, novels and video games such as Halo,” Dr Morley said.
“It’s exciting to actually see the planet out there and start measuring its properties.”
Epsilon Indi Ab is the 12th closest exoplanet currently known to Earth and the closest planet with a mass greater than Jupiter.
Astronomers chose to study Epsilon Indi A because the system suggested the possibility of planets, using a technique called radial velocity, which measures the back and forth wobble of the host star along the line of sight.
“We expected there to be a planet in this system because the radial velocity suggested its presence, but the planet we found was different to what we expected,” Dr Matthews said.
“It’s about twice as massive, it’s a little farther from its star, and its orbit is different from what we would expect. We don’t yet know what causes this discrepancy.”
“The planet’s atmosphere also seems to differ slightly from what the models predict.”
“So far, only a few atmospheric photometry measurements have been made, making it difficult to draw any conclusions, but the planet is fainter than expected at shorter wavelengths.”
“This could mean that there is a lot of methane, carbon monoxide and carbon dioxide in the planet’s atmosphere, absorbing shorter wavelengths of light. It could also suggest a very cloudy atmosphere.”
a paper The findings were published in the journal. Nature.
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E.C. Matthews othersA temperate superjupiter photographed in mid-infrared by JWST. NaturePublished online July 24, 2024, doi: 10.1038/s41586-024-07837-8
This article has been edited based on the original NASA release.
Source: www.sci.news
