Three fast-rotating Jovian Trojans identified by TESS set new population density limits

TL;DR

This study identifies the fastest rotating Jovian Trojans using TESS data, revealing a higher-than-expected density for one object, which challenges existing assumptions about Trojan densities and cohesion.

Contribution

It reports the discovery of three fast-rotating Jovian Trojans with unprecedented rotation speeds, providing new density limits and insights into their physical properties.

Findings

(13383) has a rotation period of 2.926 hours, below the breakup limit.

The density of (13383) is estimated at approximately 1.6 g/cm³, higher than previous limits.

Fast rotation and high albedo suggest a collision-induced spin-up and surface exposure.

Abstract

Here we report on the identification of the three fastest rotating Jovian Trojans with reliable population assignment, using light curve data from the Transiting Exoplanet Satellite Survey mission, also confirmed by Zwicky Transient Facility data. For two of our targets the rotation periods are moderately below the previously accepted ~5 h Jovian Trojan breakup limit (4.26 and 4.75 h), however, the rotation period of (13383) was found to be P = 2.926 h, leading to a density estimate of $\rho$ $\approx$ 1.6 $g cm^{-3}$, higher than the generally accepted $\leq$ 1 $g cm^{-3}$ density limit of Jovian Trojans. If associated with lower densities, this rotation rate requires considerable cohesion in the order of a few kPa. The relatively high albedo (pV $\approx$ 0.11) and fast rotation suggest that (13383) may have undergone an energetic collision that spun up the body and exposed bright material to the surface.