Hubble and Webb find 27 distant objects preserving clues to the solar system’s beginnings
NASA’s Hubble and James Webb telescopes jointly observed 27 newly discovered trans-Neptunian objects, icy bodies orbiting beyond Neptune. The objects’ colours resemble those of larger bodies despite expectations that collisions would have changed their surfaces; researchers also found fewer small objects than some planet-formation models predicted.
Bottom line — The 27 objects offer evidence about how planetesimals formed, while their unexpectedly low numbers leave models to explain.
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The teams combined Hubble’s visible-light observations with Webb’s infrared observations, according to the Center for Astrophysics.
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The smallest observed object was about 5 kilometres across, roughly five times smaller than objects detectable with the most sensitive ground-based telescopes, the Center for Astrophysics reports.
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The objects belong to dynamically “cold” and “hot” populations; the hot group formed between Uranus and Neptune before being scattered outwards, according to the Center for Astrophysics.
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The similar colours may indicate fewer collisions than expected, or that the objects retain their original surface compositions. Researchers have not resolved which explanation is correct, the Center for Astrophysics says.
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Webb’s measurements also showed similar size distributions in the hot and cold populations, despite their formation in different parts of the early solar system, according to the Center for Astrophysics.