The Arecibo Detection of the Coolest Radio-flaring Brown Dwarf

TL;DR

This paper reports the first radio detection of a very cool T6.5 brown dwarf, demonstrating that even ultra-cool objects with temperatures around 900 K can produce observable radio flares, opening new avenues for studying such objects.

Contribution

First detection of radio flares from a T6.5 brown dwarf, extending radio observations to cooler brown dwarfs and showing their magnetic activity at very low temperatures.

Findings

Detected sporadic, circularly polarized radio flares from 2MASS J1047+21.

Confirmed radio emission from the coolest brown dwarf to date.

Demonstrated feasibility of radio studies for ultra-cool brown dwarfs.

Abstract

Radio detection provides unique means to measure and study magnetic fields of the coolest brown dwarfs. Previous radio surveys have observed quiescent and flaring emission from brown dwarfs down to spectral type L3.5, but only upper limits have been established for even cooler objects. We report the detection of sporadic, circularly polarized flares from the T6.5 dwarf, 2MASS J1047+21, with the Arecibo radio telescope at 4.75 GHz. This is by far the coolest brown dwarf yet detected at radio frequencies. The fact that such an object is capable of generating observable, coherent radio emission, despite its very low, ~900 K temperature, demonstrates the feasibility of studies of brown dwarfs in the meagerly explored LTY spectral range, using radio detection as a tool.