The James Webb Space Telescope (JWST) has achieved another remarkable milestone in the realm of astronomy. On Tuesday, June 10, astronomers announced that JWST successfully captured a direct image of a distant, frigid planet located in a solar system distinct from our own. This exoplanet, designated as 14 Herculis c (or 14 Her c for short), orbits a sun-like star approximately 60 light-years away from Earth, nestled in the constellation Hercules.
In the newly released image from the James Webb Space Telescope, 14 Her c appears as a faint, fuzzy orange dot. This unique coloration is attributed to the heat radiating from the planet's atmosphere, translated into visible hues. Astronomers estimate that 14 Her c formed around 4 billion years ago and maintains a chilly atmospheric temperature of just 26 degrees Fahrenheit (minus 3 degrees Celsius). This distant planet orbits its star at an impressive distance of about 1.4 billion miles (2.2 billion kilometers), which is roughly 15 times farther than Earth is from the Sun.
If 14 Her c were placed within our solar system, it would reside between Saturn and Uranus. However, unlike the orderly, flat orbits of the planets in our own system, the 14 Herculis system exhibits a dramatically misaligned configuration. The two known planets in this system, including 14 Her c, orbit at angles of approximately 40 degrees to one another, resulting in an X-like crossing pattern around their star. This unusual layout may have been influenced by the early ejection of a third massive planet from the system, which could have thrown the remaining two planets into a gravitational tug-of-war, as explained by Balmer, a key researcher on the project.
Despite the apparent instability of their orbits, these wobbles have proven to be stable over long periods, providing an exciting opportunity for astronomers to investigate the kinds of planet-planet scatterings that could lead to such an exotic configuration of orbits.
Of the nearly 6,000 known exoplanets, only a small fraction have been directly imaged, making this achievement particularly noteworthy. Balmer noted that capturing images of exoplanets is a technically daunting task. "Planets shine thousands — and, in some cases, even millions or billions — of times fainter than the stars they orbit," he explained, likening the challenge to "fireflies next to lighthouses." Most of the directly imaged exoplanets to date are hot, young gas giants that emit enough infrared light to stand out against the bright glare of their host stars. In contrast, colder and older planets like 14 Her c are typically far too dim for detection.
Fortunately, the tilted and off-kilter orbit of 14 Her c presents a unique advantage for direct imaging. Balmer confidently stated that JWST could resolve the outermost planet in the system. By utilizing the telescope's specialized starlight-blocking device known as a coronagraph, Balmer and his team successfully isolated the planet's faint infrared glow. "We are now able to add to the catalog of older exoplanets that are far colder than we've directly observed before Webb," Balmer remarked.
Based on 14 Her c's estimated age of around 4 billion years, its mass of about seven times that of Jupiter, and computer models predicting how planets evolve, researchers initially expected the planet to appear brighter or emit more heat than it actually does in the JWST image. Balmer stated, "The planet's actually significantly fainter than what we'd expect." However, this does not suggest a flaw in evolutionary models.
Using JWST to probe the planet's atmosphere, astronomers detected carbon dioxide and carbon monoxide at temperatures where methane would typically be expected. This indicates that strong updrafts are likely transporting hot gases from the depths of the atmosphere to its colder upper layers. Balmer explained that these gases, possibly accompanied by thin icy clouds, help retain heat, making the planet appear cooler and fainter than anticipated.
The discovery of 14 Her c has expanded the range of exoplanets that astronomers can study. By examining planets with diverse masses, temperatures, and orbital histories, scientists aim to gain a deeper understanding of how planetary systems, including our own, are formed and evolve. As Balmer noted, "We want to understand how these planets change because we want to understand how we got here." This groundbreaking research not only sheds light on 14 Herculis c but also opens new avenues for exploring the mysteries of the universe.
