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| This image of exoplanet Epsilon Indi Ab was captured by the MIRI coronagraph on NASA’s James Webb Space Telescope. Epsilon Indi A’s starlight was blocked, resulting in a dark circle marked by a dashed white line. Epsilon Indi Ab, one of the coldest directly imaged exoplanets, appears as a point source. Blue represents light at 10.6 microns, while orange depicts 15.5 microns. |
An international team of astronomers, utilizing NASA’s James Webb Space Telescope, has achieved a milestone by directly imaging an exoplanet named Epsilon Indi Ab. This planet, located approximately 12 light-years from Earth, stands out as one of the coldest exoplanets ever observed.
Epsilon Indi Ab is a massive planet, several times larger than Jupiter, orbiting a K-type star known as Epsilon Indi A. This star, similar in age to our Sun but slightly cooler, was targeted for observation due to previous indirect indications of a planetary presence through radial velocity measurements.
Lead author Elisabeth Matthews from the Max Planck Institute for Astronomy emphasized the significance of this discovery, noting that Epsilon Indi Ab closely resembles Jupiter in many aspects, albeit being slightly warmer and more massive than other directly imaged planets.
The observation of Epsilon Indi Ab was made possible by Webb’s Mid-Infrared Instrument (MIRI) coronagraph, a technology crucial for capturing faint mid-infrared emissions that are challenging to detect from ground-based observatories. This allowed astronomers to discern the planet’s presence and begin characterizing its atmospheric properties.
One of the most intriguing aspects of Epsilon Indi Ab is its estimated temperature of 2 degrees Celsius (35 degrees Fahrenheit), making it one of the coldest imaged exoplanets and colder than most free-floating brown dwarfs. This presents a unique opportunity for scientists to study a true analog to planets in our own Solar System.
The team’s findings, published in Nature, also highlight discrepancies between initial predictions and actual observations. Matthews mentioned that Epsilon Indi Ab is twice as massive as anticipated, orbits farther from its star, and displays unexpected atmospheric characteristics. Initial photometric measurements suggest a potentially methane-rich and cloudy atmosphere, contributing to its faint appearance at certain wavelengths.
Looking ahead, the team plans to conduct further observations with Webb to gather more comprehensive data on Epsilon Indi Ab’s atmosphere. They hope to uncover insights into planetary formation and atmospheric compositions of similar exoplanets.
This groundbreaking discovery underscores the capability of the James Webb Space Telescope and sets the stage for future missions, including NASA’s upcoming Nancy Grace Roman Space Telescope, which aims to push the boundaries of direct imaging technology even further.
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Key Points:
- Direct imaging of Epsilon Indi Ab, a cold exoplanet 12 light-years away, using NASA’s James Webb Space Telescope.
- Planet is several times more massive than Jupiter, orbiting a K-type star similar to our Sun.
- Discrepancies found between predictions and observations suggest unexpected mass, orbital distance, and atmospheric composition.
- Significant methane and cloudiness observed in the planet’s atmosphere, contributing to its faint appearance.
- Insights gained will inform future missions and deepen understanding of exoplanetary atmospheres and formation.
