First Detection of an Ultracool Dwarf at 340 MHz: VLITE Observations of EI Cancri AB

TL;DR

This paper reports the first detection of radio emission from an ultracool dwarf at 340 MHz, using VLITE observations of the EI Cancri binary system, expanding understanding of low-frequency stellar radio phenomena.

Contribution

It presents the first-ever detection of an ultracool dwarf at 340 MHz, demonstrating VLITE's capability to probe this frequency regime for such objects.

Findings

First ultracool dwarf detection at 340 MHz

VLITE effectively detects low-frequency stellar emissions

EI Cancri shows magnetic activity at this frequency

Abstract

Magnetically driven phenomena such as flaring events and aurorae lead ultracool dwarfs to emit at radio frequencies. Despite decades of scrutiny, a comprehensive physical understanding of their radio emission at different frequencies remains elusive, spurring on additional study of these complex objects. The VLA Low-band Ionosphere and Transient Experiment (VLITE) is a commensal instrument operating at 340 MHz on the Very Large Array. A key advantage of 340 MHz observations is their sensitivity to circumstellar disks and planets at understudied distances from the stellar disk, intermediate between GHz and low MHz sensitivities. Hard-to-find coronal mass ejections are also predicted to be detectable at 340 MHz. However, this frequency regime is relatively unprobed in ultracool dwarf studies, with few searches and no published detections to date. Here we highlight our investigation of the nearby M7-M7 binary, EI Cancri. EI Cancri AB is magnetically active, yet has an uncharacteristically long 83-day candidate rotation period within the system. With the VLITE detection of the EI Cancri system, we present the first ever detection of ultracool dwarf emission at 340 MHz.