Beyond Neptune lies the Kuiper Belt, a region filled with asteroids and small celestial bodies. This zone, extending to the Oort Cloud, constitutes the outer Solar System, a region still shrouded in mystery.
"Looking outside of the Solar System, a typical planetary disk extends about 100 AU from the host star (100 times the distance between the Earth and the Sun), and the Kuiper Belt, which is estimated to extend about 50 AU, is very compact. Based on this comparison, we think that the primordial solar nebula, from which the Solar System was born, may have extended further out than the present-day Kuiper Belt," says Dr. Fumi Yoshida (Industrial Medical University of Japan; Center for Planetary Exploration Research, Chiba Institute of Technology), who led the research.
Current data indicates that the outer edge of the Kuiper Belt ends abruptly around 50 AU. This could either mark the boundary of the primordial solar nebula or be the result of interactions with undiscovered outer bodies. Identifying objects beyond this limit could reveal whether the Kuiper Belt extends further, enhancing our understanding of Solar System evolution.
NASA's New Horizons mission, which flew by Pluto in 2015 and the Kuiper Belt object Arrokoth in 2019, continues its exploration of the outer Solar System. The Subaru Telescope has aided this mission by locating new Kuiper Belt objects for New Horizons to study.
Using the Hyper Suprime-Cam (HSC), the search focused on two fields along the spacecraft's trajectory, covering an area equivalent to 18 full moons. Over 30 half-nights of observations, the New Horizons team discovered more than 240 outer Solar System objects.
Dr. Yoshida's team applied a new method to the HSC data, discovering seven new outer Solar System objects. This method, developed by JAXA, overlays 32 consecutive images to detect moving objects. Two of these newly found objects have had their orbits preliminarily determined and received provisional designations from the Minor Planet Center.
Historically, the number of Kuiper Belt objects drops significantly beyond 50 AU, suggesting this as its outer edge. However, the semi-major axes of the two newly designated objects are both greater than 50 AU. Continued discoveries in this range could suggest the Kuiper Belt extends further than previously believed. The collaboration between the Subaru Telescope and New Horizons aims to explore deeper into the outer Solar System than ever before.
"The mission team's search for Kuiper Belt objects using HSC continues to this day, and a series of papers will be published in the future, mainly by the North American group. This research, the discovery of sources with the potential to expand the Kuiper Belt region using a method developed in Japan and led by Japanese researchers, serves as a precursor to those publications," says Dr. Yoshida.
Research Report:A deep analysis for New Horizons' KBO search images
Related Links
New Horizon at JHU
Subaru Telescope
The million outer planets of a star called Sol
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