The DECam Ecliptic Exploration Project (DEEP) IV: Constraints on the shape distribution of bright TNOs

TL;DR

This paper reports the discovery and analysis of 26 bright trans-Neptunian objects, revealing that most are non-spherical or contact binaries, and suggests binarity may depend on size.

Contribution

It introduces a novel application of computer vision techniques to identify TNOs and models their shape distribution, providing new insights into their physical properties.

Findings

Most TNOs have axis ratios b/a < 0.5, indicating non-spherical shapes.

Data is consistent with a high fraction of contact binaries among TNOs.

Binarity fraction may vary with TNO size.

Abstract

We present the methods and results from the discovery and photometric measurement of 26 bright (VR $>$ 24 trans-Neptunian objects (TNOs) during the first year (2019-20) of the DECam Ecliptic Exploration Project (DEEP). The DEEP survey is an observational TNO survey with wide sky coverage, high sensitivity, and a fast photometric cadence. We apply a computer vision technique known as a progressive probabilistic Hough transform to identify linearly-moving transient sources within DEEP photometric catalogs. After subsequent visual vetting, we provide a photometric and astrometric catalog of our TNOs. By modeling the partial lightcurve amplitude distribution of the DEEP TNOs using Monte Carlo techniques, we find our data to be most consistent with an average TNO axis ratio b/a $<$ 0.5, implying a population dominated by non-spherical objects. Based on ellipsoidal gravitational stability arguments, we find our data to be consistent with a TNO population containing a high fraction of contact binaries or other extremely non-spherical objects. We also discuss our data as evidence that the expected binarity fraction of TNOs may be size-dependent.