# The Northern Arc of $\epsilon$ Eridani's Debris Ring as Seen by ALMA

## TL;DR

This paper reports ALMA observations of the nearby debris disc around $$ Eridani, revealing a narrow, ring-like structure with potential planetary resonances and tentative clump detections, advancing understanding of exoplanetary debris systems.

## Contribution

First ALMA imaging of $$ Eridani's debris disc, revealing its narrow structure and possible planetary influences, providing new insights into its morphology and composition.

## Key findings

- Disc is narrow with a width of 11-13AU.
- Detected potential clumps, some likely background galaxies.
- Confirmed stellar chromospheric emission at the star.

## Abstract

We present the first ALMA observations of the closest known extrasolar debris disc. This disc orbits the star $\epsilon$ Eridani, a K-type star just 3.2pc away. Due to the proximity of the star, the entire disc cannot fit within the ALMA field of view. Therefore, the observations have been centred 18" North of the star, providing us with a clear detection of the northern arc of the ring, at a wavelength of 1.3mm. The observed disc emission is found to be narrow with a width of just 11-13AU. The fractional disc width we find is comparable to that of the Solar System's Kuiper Belt and makes this one of the narrowest debris discs known. If the inner and outer edges are due to resonances with a planet then this planet likely has a semi-major axis of 48AU. We find tentative evidence for clumps in the ring, although there is a strong chance that at least one is a background galaxy. We confirm, at much higher significance, the previous detection of an unresolved emission at the star that is above the level of the photosphere and attribute this excess to stellar chromospheric emission.