ALMA Images the Eccentric HD 53143 Debris Disk

TL;DR

ALMA imaging reveals the HD 53143 debris disk to be highly eccentric with a complex structure, indicating possible past dynamical interactions, and shows variability in stellar flux suggesting stellar activity.

Contribution

This is the first millimeter imaging of the HD 53143 debris disk, revealing its high eccentricity and complex structure, and providing insights into its dynamical history.

Findings

Most eccentric debris disk observed to date with eccentricity 0.21

Detection of apocenter glow in the debris disk

Evidence of potential inner disk and past scattering events

Abstract

We present ALMA 1.3 mm observations of the HD~53143 debris disk - the first infrared or millimeter image produced of this ~1 Gyr-old solar-analogue. Previous HST STIS coronagraphic imaging did not detect flux along the minor axis of the disk which could suggest a face-on geometry with two 'clumps' of dust. These ALMA observations reveal a disk with a strikingly different structure. In order to fit models to the millimeter visibilities and constrain the uncertainties on the disk parameters, we adopt an MCMC approach. This is the most eccentric debris disk observed to date with a forced eccentricity of $0.21\pm0.02$, nearly twice that of the Fomalhaut debris disk, and also displays apocenter glow. Although this eccentric model fits the outer debris disk well, there are significant interior residuals remaining that may suggest a possible edge-on inner disk, which remains unresolved in these observations. Combined with the observed structure difference between HST and ALMA, these results suggest a potential previous scattering event or dynamical instability in this system. We also note that the stellar flux changes considerably over the course of our observations, suggesting flaring at millimeter wavelengths. Using simultaneous TESS observations, we determine the stellar rotation period to be $9.6\pm0.1$ days.