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Using the James Webb Space Telescope (JWST), astronomers have investigated a new “super Jupiter” planet that is one of the coldest worlds ever seen outside the solar system.
The extrasolar planet or “exoplanet” is located in the triple star system Epsilon Indi, which sits about 12 light years away. The planet is named Eps Ind Ab and has a mass of about six times that of Jupiter; It orbits its red dwarf parent star at a distance similar to that between Neptune and the sun. This gives the earth’s surface temperature around 32 degrees Fahrenheit (0 degrees Celsius) and means that one orbit of the planet takes about 200 Earth years.
The JWST was able to image the exoplanet using the sensitive infrared capabilities of the Mid-Infrared Instrument (MIRI). The Eps Ind Ab investigation could help astronomers better understand the evolution of gas giant planets and their systems.
This is the first time that the powerful space telescope has managed to image an exoplanet that has not been imaged from the ground before. Eps Ind Ab is the coolest exoplanet studied by the JWST to date.
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“We were excited when we realized we had imaged this new planet,” Elisabeth Matthews, a researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany and lead author of a study on the discovery, said in a statement. “To our surprise, the bright spot seen in our MIRI images did not match the position we expected for the planet.”
Matthews added that previous studies had correctly identified a planet in this system, but had underestimated the mass and orbital separation of this super-Jupiter gas giant. The team was able to correct this with the help of the JWST.
The team determined that the planet has a highly elliptical, or “flat,” orbit that brings it to a distance of about 20 times the distance between Earth and the sun at its closest point. At the longest point in its orbit, Eps Ind Ab is 50 times farther from its parent star than the average distance between Earth and the sun.
Earth’s parent star, a red dwarf named Eps Ind A, has two companions. Both are brown dwarfs or “failed stars”, so named because they are objects that resemble stars but do not have enough mass. gather to trigger nuclear fusion processes in their cores that define what a “main sequence star” is.
cold planet; hot topic
Until now, scientists have only been able to detect a few scattered cold planets with wide orbits outside the solar system. And even those have been detected indirectly, through an exoplanet detection technique called the “radial velocity method,” which measures the “wobble” that an orbiting planet causes in the motion of its parent star.
Planets like this are difficult to detect with other methods. Cold planets are far from their stars, and their orbits are unlikely to cause planets to cross, or “transit,” the face of their star (as seen from our position in the solar system). Such transits are usually important for detecting exoplanets because they cause pulses in the starlight as they lead detectors in our vicinity. Specifically, starlight appears to “dip” during transit.
This means that the transit method for detecting exoplanets is largely out of the question for these planets, but the radial velocity method is also unreliable because only a small amount of wide orbits make a detectable “tug” on a star.
The radial velocity method was used to study Eps Ind Ab, but as only a small slice of its orbit could be probed, this led to the incorrect conclusion that Super Jupiter took 43 Earth years to orbit. star completion. . It would take years of observation to get a more accurate picture of this planet’s orbit with this method.
Aware of these difficulties, Matthews and his colleagues decided to take a different approach, trying to directly image Eps Ind Ab.
Directly imaging an exoplanet is a tough proposition. Not only are the nearest exoplanets many light years away, but most astronomy cameras are also blinded by the bright lights of the stars when trying to observe orbiting planets.
So, the team took advantage of MIRI’s “coronagraph,” a star-blocking shield that essentially simulates an eclipse. MIRI was also the perfect tool for this investigation because it sees the cosmos in thermal, or mid-infrared, light. This is the kind of light cold things that arise brightly.
The researchers were helped by the fact that Eps Ind Ab is relatively close to Earth, being 12 light years away. The smaller distance between the JWST and this target exoplanet made the distance between Eps Ind Ab and its star appear larger. This apparent wider separation means there is a better chance of mitigating the blinding effect of starlight.
“We found a signal in our data that was not consistent with the expected exoplanet,” Matthews said, pointing out that Eps Ind Ab appeared as a point of light in the MIRI image that was not in the predicted location. “But the planet still looked like a giant planet.”
To confirm this, the team still had to make sure that what they saw was not the result of background light coming from a more distant star. Thanks to re-examinations of the same region using the Very Large Telescope (VLT), the scientists discovered something small. This object happened to be at the right point if indeed the sign belonged to the star Eps Ind A.
Matthews and colleagues also attempted to understand Eps Ind Ab’s atmosphere using the MIRI data. This showed that the super-Jupiter appears to be packed with heavy elements, especially carbon, which takes up molecules such as methane, carbon dioxide and carbon monoxide, which are commonly found in gas giant planets.
Another explanation for this is that the planet’s atmosphere is cloudy. All of this is to say that more research is needed to better understand Eps Ind Ab.
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The team now plans to obtain spectra of light from Eps Ind Ab that could provide a detailed “fingerprint” of Super-Jupiter’s chemical composition and general climate.
“In the long run, we hope to also look at other nearby planetary systems to search for cold gas giants that may have escaped detection,” Matthews said. “Such a survey would be the basis for a better understanding of how gas planets form and evolve.”
The team’s research was published on Wednesday (July 24) in the journal Nature.
