CFHT UM2025 - Presentation Details
Abstract Details
Title: The Outer Solar System in the near-UV
Presenter: Nicole Tan
Abstract:
The Canada-France-Hawaii Telescope (CFHT) provides unique access to the outer Solar System in the near-UV because of its short-wavelength sensitivity. While trillions of small icy-rocky bodies inhabit the trans-Neptunian region, few have been studied at near-UV wavelengths. Most trans-Neptunian objects (TNOs) are too faint for spectroscopy, so their surface composition must be inferred from broad-band colours—historically measured in the optical and near-infrared. Using u-band data from the Canada-France-Hawaii Telescope (CFHT), we present the results of the near-UV component of the Colours of the Outer Solar System Origins Survey (Col-OSSOS). This is the first major near-UV survey of the outer Solar System, totalling 82.7 hours of observations. We report near-UV/optical colours and upper limits on 163 TNOs discovered by the Outer Solar System Origins Survey (OSSOS), spanning all TNO dynamical classes. 52 detected TNOs have two-telescope simultaneous photometry in grJ from the Gemini-North telescope as part of the main Col-OSSOS optical/near-infrared survey. We confirm that the known general trend for TNO surfaces to have constant spectral slope continues into the near-UV/optical colour space. However, we find that cold classical TNOs are more likely to be on this reddening curve than dynamically excited TNOs, which instead tend toward the blue in the near-UV. Based on our pan-chromatic ugrJ photometry, we find that three spectral groups emerge, enabling us to test the two-class model of TNO surfaces from Col-OSSOS. We also place these results in context with recent JWST TNO spectra and make predictions for the LSST u-band TNO yield, highlighting CFHT’s critical role in expanding our understanding of TNO surface properties.