A Survey of Cometary Dust Trails in TESS

Cometary dust trails are long-lived streams of large grains ejected from comet nuclei at low velocities and are widely thought to be the major source of outer Solar System material migrating inward. These trails are considered to be one of the primary delivery methods of organic material on Earth and play a key role in replenishing zodiacal dust. However, their study is complicated by the steep size distribution of cometary dust, meaning smaller particles overwhelmingly outnumber larger ones and dominate the scattered sunlight. While radiation pressure quickly removes the smallest grains, the remaining dust trail consists of larger, dimmer particles that require long-exposure imaging to detect. This also means significant telescope time is needed to properly image them. We plan to perform a comparative survey of trails from multiple comets using the Transiting Exoplanet Survey Satellite (TESS).

TESS has revolutionized the field of cometary trail analysis. Although designed to detect transiting exoplanets, the large pixel size and the ability to coadd 27 days of continuous observations make it ideal for detecting faint, extended features like dust trails (Figure 1). TESS’s wide-field coverage (24°×96° per sector) allows us to observe dust trails that extend across multiple sectors. With TESS data we aim to model trail brightness distributions to derive particle sizes and ejection velocities, quantify dust production rates and total mass ejected from comet nuclei, and constrain the mass transport rate of cometary material into the inner Solar System. To date TESS has detected potential trails in 56 comets, 32 of which are in comets that have not previously been known to exhibit dust trails. Previously, 44 comets were known to have trails (Kelley 2021), which means the new comets seen with TESS are likely to double the number of comets with identified trails. 

To analyze this data, we will modify an established data reduction pipeline (Farnham et al.  2021), develop a new automated process for trail extraction and analysis, and adapt an existing dust dynamics model (Kelley 2023). Preliminary results and progress will be reported as the project advances.