Discover the Coldest Planet Ever Observed Orbiting a Dying Star

Astronomers using the James Webb Space Telescope have made a remarkable discovery: they’ve detected the faint glow of an extremely cold planet, colder than any previously observed directly. This finding sheds light on the diverse and extreme conditions of planets in our universe.

The planet, called WD 1856+534 b, was first identified in 2020. It’s twice as old as our solar system, roughly the size of Jupiter, but about six times its mass. What’s striking is its chilling average temperature of around -125°F (-87°C). This makes it the coldest exoplanet to ever be observed through its own emitted light. The research detailing this exoplanet and its thermal emissions is currently available on arXiv.

WD 1856 b orbits a white dwarf star, which is the remains of a dead star. This dim star allows the planet’s faint light to be visible. Typically, bright stars overpower the light of their surrounding planets, making detection difficult. Astronomer Mary Anne Limbach from the University of Michigan contributed valuable insights to this research.

Interestingly, WD 1856 b is located very close to its white dwarf star—just 0.02 astronomical units away. That’s even closer than Mercury’s orbit around our Sun. The research team noted that WD 1856+534 b is the first known intact exoplanet found in the “forbidden zone” of a white dwarf. This region previously posed a risk for planets during the star’s red giant phase, yet this planet’s presence suggests that planets can indeed migrate into such close orbits around white dwarfs.

In terms of temperature, WD 1856 b stands out. It’s significantly colder than other planets like Epsilon Indi Ab, which was studied by Webb last year. Epsilon Indi Ab had an estimated temperature of 35°F (2°C) at that time, making WD 1856 b a true standout.

This discovery also clarifies WD 1856 b’s classification. Previously thought to possibly be a low-mass brown dwarf, its low temperature and revised mass (no more than 5.9 times that of Jupiter) now confirm that it belongs to the extensive catalog of exoplanets compiled by scientists.

This research highlights the impressive capabilities of the James Webb Space Telescope in studying cold and mature planets. It serves as a reminder that even planets orbiting the remnants of dead stars can emit light, no matter how faint.

Overall, the detection of WD 1856+534 b offers a glimpse into the complex dynamics of planetary systems and the surprising environments where planets can thrive. As we probe deeper into the universe, findings like these not only expand our understanding but also fuel curiosity about what other astonishing worlds are waiting to be discovered.

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exoplanets,webb space telescope,white dwarfs