David Rollinson | Searcharxiv

arXiv2026

Photometry of Fireballs using High Frame Rate Cameras

Fast sampling photometry is essential for characterising fireballs and their fragmentation episodes which link to the meteoroid internal structure. Accurate measurements remain challenging due to the large required dynamic range of up to 10 stellar magnitudes driving up operational complexity and cost. We developed an all-sky camera system operating at up to 500 frames per second featuring a novel Detection Localised Auto-brightness Control. Custom software manages high data throughput via transient detection and region-of-interest saving with real-time photometry. Two field deployments validate photometric accuracy against conventional 30 frames per second cameras and demonstrate the successful capture of a bright magnitude -15 fireball with minimal saturation. The system achieves an effective dynamic range between apparent magnitudes -3 and -17 capturing minimally saturated light curves for most fireballs. A successful semi-empirical fragmentation analysis verifies its ability to provide data for detailed physical modelling. The primary application for this validated system will be as a core component of the Global Fireball Observatory's next-generation instrumentation. The intention is to deploy it in a hybrid observatory, operating alongside a dedicated high-resolution astrometric camera. This configuration will allow the network to simultaneously capture precise trajectory data for orbit and fall-line calculations and acquire complete, unsaturated high dynamic range light curves at high temporal resolution for detailed physical analysis, combining the strengths of both systems.

astro-ph.IM↗

arXiv2024

Properties of outer solar system pebbles during planetesimal formation from meteor observations

In the late stages of accretion leading up to the formation of planetesimals, particles grew to pebbles the size of 1-mm to tens of cm. That is the same size range that dominates the present-day comet mass loss. Meteoroids that size cause visible meteors on Earth. Here, we hypothesize that the size distribution and the physical and chemical properties of young meteoroid streams still contain information about the conditions in the solar nebula during these late stages of accretion. From observations of 47 young meteor showers, we find that freshly ejected meteoroids from long-period comets tend to have low bulk density and are distributed with equal surface area per log-mass interval (magnitude distribution index chi ~ 1.85), suggesting gentle accretion conditions. Jupiter-family comets, on the other hand, mostly produce meteoroids twice as dense and distributed with a steeper chi ~ 2.15 or even chi ~ 2.5, which implies that those pebbles grew from particles fragmenting in a collisional cascade or by catastrophic collisions, respectively. Both comet populations contain an admixture of compact materials that are sometimes sodium-poor, but Jupiter-family comets show a higher percentage (~8% on average) than long-period comet showers (~4%), and a wider range. While there are exceptions in both groups, the implication is that most long-period comets formed under gentle particle growth conditions, possibly near the 30 AU edge of the Trans Neptunian Disk, while most Jupiter family comets formed closer to the Sun where pebbles reached or passed the fragmentation barrier. This is possible if the Scattered Disk represents all objects scattered by Neptune during its migration, while the present-day outer Oort cloud formed only during and after the Sun had moved away from sibling stars.

astro-ph.EP↗