According to the US National Aeronautics and Space Administration (NASA), for the first time scientists have collaborated to use the Hubble Space Telescope and the James Webb Space Telescope to study distant transneptunian objects (TNOs), including some of the smallest and fainter objects ever observed directly.
TNOs are small, cold, and icy objects moving around the Sun outside the orbit of Neptune. Most of them are 100 million times fainter than visible objects.
In two studies published in The Astronomical Journal, scientific groups analyzed the colors, composition, size and orbit of 27 newly discovered small, faint TNOs. Hubble observed visible light, while Webb collected infrared data, helping researchers have a more comprehensive view of these objects.
TNO is considered the "relic" of the early stages of planet formation. At that time, dust and rock particles orbiting the Sun aggregate into solid objects of a city-sized size, called planetary microorganisms, before continuing to merge to form a planet.
The researchers focused on two groups of TNOs. The "cold" group is located on relatively circular orbits, close to the original orbit in the plane of the Solar System. The "hot" group forms between the current positions of Uranus and Neptune, then is pushed away as gas giant planets move in the early stages of the Solar System.
Surprisingly, small TNOs still have the same color as larger objects in the same group. This suggests that collisions may not significantly change their surfaces, or that these celestial bodies still retain their original composition from the time of formation.
Research led by research student Dr. Anastasia Morgan of the University of Northern Arizona suggests that the smallest objects seem to be "remembering" their formation history.
Webb data also shows that the two TNO groups have relatively similar size distributions, although formed in different regions. Notably, the number of extremely small celestial bodies is lower than expected from some planetary formation models.
The smallest object observed has a diameter of only about 5km, about 5 times smaller than the detection limit of the most sensitive ground-based telescopes. NASA said that combining Hubble and Webb will help scientists continue to decode the formation and evolution of the Solar System.
