Coldest Exoplanet Found Orbiting Dead Star
The James Webb Space Telescope (JWST) has achieved a remarkable feat: the direct observation of an exoplanet colder than any previously directly imaged. This exoplanet, designated WD 1856+534 b, is a significant discovery, pushing the boundaries of our understanding of planetary systems.
A Unique Discovery
WD 1856+534 b, discovered in 2020, presents a unique set of characteristics. Roughly the size of Jupiter but six times more massive, it boasts an incredibly low average temperature of -87° Celsius (-125° Fahrenheit). This makes it the coldest exoplanet ever directly observed using its own emitted light. The research, currently available on arXiv, details the exoplanet's thermal emission.
Orbiting a White Dwarf
What makes this detection even more remarkable is the exoplanet's location. It orbits a white dwarf, the remnant core of a dead star. The dimness of the white dwarf, unlike brighter stars, allowed JWST to clearly observe the faint glow of the orbiting planet. This observation challenges previous assumptions, as the planet exists within the "forbidden zone" – a region where planets would typically be engulfed during the star's red giant phase. Its survival offers compelling evidence of planetary migration into close orbits around white dwarfs.
A Cold World's Significance
The discovery of WD 1856+534 b significantly alters our understanding of planetary systems. Its extreme temperature eclipses even Epsilon Indi Ab, previously considered the coldest imaged exoplanet. This finding underscores JWST's capabilities in studying cold, mature planets and highlights the potential for discovering similar worlds orbiting stellar remnants. The analysis also confirms WD 1856+534 b as a planet, settling a previous debate about its potential classification as a low-mass brown dwarf.
Source: Gizmodo