Characterising transneptunian binaries in the hubble archive using Markov Chain Monte Carlo methods

Abstract

We measured the photometric properties of trans-Neptunian binary (TNB) components in optical and near-infrared wavelengths to characterise their surfaces. As remnants of the early protoplanetary disk, trans-Neptunian objects provide insights into the evolution of the Solar System and the effects of planetary migration. Mass and density estimates of TNBs can be combined with photometry to infer potential compositions, informing models of planetesimal formation and dynamical evolution of the Solar System. The foundation this work was the development of a sophisticated Markov Chain Monte Carlo-based Point Spread Function fitting algorithm. This code was applied to Hubble Space Telescope Wide Field Camera 3 (WFC3) data of TNBs to obtain component magnitudes, colours and variability. Reliable fits were obtained for 23 of an available 28 WFC3 binaries, with 14 having optical F606W-F814W colour measurements available. When combined with those of Benecchi et al. (2009), we found 30 of the 34 binaries had consistent component colours, implying the components of each binary formed from similar material. Available near-infrared F139M-F153M and F814W-F139M colours showed all binaries had component colours consistent within measured 1-σ uncertainties, indicating the component colour correlation extends into the near-infrared. We also produced 22 pairs of partial component light curves for 16 binaries, with 19 primary and 14 secondary light curves having variations <0.15 mag, in agreement with smaller objects having larger light curve amplitudes due to elongation. We found no variation in component colours over time, though data was limited. Longer-term measurements of component absolute magnitudes showed variations likely attributable to rotational effects. Finally, we measured component relative reflectances, finding 1998 SM165, 2000 WT169 and 2005 EF298 show possible spectral variations over time, implying changes in composition with rotation. Significant differences were found in 2005 SF278’s component reflectances despite correlated colours, suggesting broader spectral coverage is required to understand object surfaces.

Date of Award	Jul 2023
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Northern Ireland Department for the Economy
Supervisor	Alan Fitzsimmons (Supervisor) & Megan Schwamb (Supervisor)