# Flat Spectrum Radio Continuum Emission Associated with $\epsilon$ Eridani

## TL;DR

This study uses VLA observations at 33 GHz to confirm that the flat-spectrum radio emission near epsilon Eridani originates from the star itself, likely due to a stellar wind with a high mass-loss rate, rather than from a nearby exoplanet.

## Contribution

First direct detection and localization of epsilon Eridani's radio emission at 33 GHz, supporting stellar origin over planetary hypothesis, and modeling it as a stellar wind with a high mass-loss rate.

## Key findings

- Radio emission coincides with star within 0.2 AU
- Emission consistent with optically thin free-free emission
- Stellar wind model suggests a mass-loss rate 3,300 times solar

## Abstract

We present Very Large Array observations at 33.0 GHz that detect emission coincident with $\epsilon$ Eridani to within $0\rlap.{"}07$ (0.2 AU at the distance of this star), with a positional accuracy of $0\rlap.{"}05$. This result strongly supports the suggestion of previous authors that the quiescent centimeter emission comes from the star and not from a proposed giant exoplanet with a semi-major axis of $\sim1\rlap.{"}0$ (3.4 AU). The centimeter emission is remarkably flat and is consistent with optically thin free-free emission. In particular, it can be modeled as a stellar wind with a mass loss rate of the order of $6.6 \times 10^{-11}~ M_\odot ~yr^{-1}$, which is 3,300 times the solar value, exceeding other estimates of this star's wind. However, interpretation of the emission in terms of other thermal mechanisms like coronal free-free and gyroresonance emission cannot be discarded.