Linking System of Jets to the Non-Gravitational Acceleration of 3I/ATLAS

TL;DR

This study links observed jet orientations and non-gravitational accelerations of 3I/ATLAS to understand its dynamics, using jet morphology, precise measurements, and modeling to estimate thrust and acceleration components.

Contribution

It introduces a method to connect jet position angles with non-gravitational accelerations, providing new insights into the comet's physical forces and uncertainties involved.

Findings

Jet2 aligns with the transverse direction within 0.5 degrees on 2025-11-30.

Jet3 is closest to the normal direction with a 25-degree offset.

Jet2 shows a monotonic PA drift over 24 minutes on 2025-12-27.

Abstract

Building on the jet morphology and periodic wobble analysis of 3I/ATLAS in Scarmato & Loeb (2026), we link observed jet position angles (PAs) and the non-gravitational acceleration components (A1,A2,A3) in the 3D RTN (radial, transverse, normal) frame relative to the Sun. We: (i) compute RTN directions from heliocentric state vectors and project them on the sky at the measured astromet ric pointings; (ii) compare projected RTN PAs to three persistent jets (Jet1-Jet2-Jet3) and quantify angular offsets; and (iii) estimate order-of-magnitude thrust and accelerations from HST/WFC3-UVIS F350LP net counts via transformations from photometry to cross-section, dust mass, mass-loss rate, and thrust. We explicitly document the uncertainties through background handling, phase-function systematics, and geometric degeneracies along the line of sight. For U.T. 2025-11-30.80903, Jet2 is aligned with the projected transverse direction to within 0.5 degs, while Jet3 is the closest to the pro jected normal direction with a moderate offset (about 25 degs). For UT 2025-12-27, Jet2 exhibits a monotonic PA drift over 24 minutes with a larger oscillation amplitude.