Revealing The Millimeter Environment of the New FU Orionis Candidate HBC722 with the Submillimeter Array

TL;DR

This study uses submillimeter observations to explore the environment around FU Orionis candidate HBC722, revealing nearby protostars, outflows, and setting limits on its circumstellar disk mass, contributing to understanding FUor phenomena.

Contribution

It provides the first detailed submillimeter imaging of HBC722's environment, identifying nearby protostars and constraining its disk mass, which was previously uncharacterized.

Findings

Seven continuum sources detected near HBC722, none of which is HBC722 itself.

An outflow is observed, driven by a nearby Class 0 protostar, not HBC722.

HBC722's circumstellar disk mass is limited to less than 0.02 solar masses.

Abstract

We present 230 GHz Submillimeter Array continuum and molecular line observations of the newly discovered FUor candidate HBC722. We report the detection of seven 1.3 mm continuum sources in the vicinity of HBC722, none of which correspond to HBC722 itself. We compile infrared and submillimeter continuum photometry of each source from previous studies and conclude that three are Class 0 embedded protostars, one is a Class I embedded protostar, one is a Class I/II transition object, and two are either starless cores or very young, very low luminosity protostars or first hydrostatic cores. We detect a northwest-southeast outflow, consistent with the previous detection of such an outflow in low-resolution, single-dish observations, and note that its axis may be precessing. We show that this outflow is centered on and driven by one of the nearby Class 0 sources rather than HBC722, and find no conclusive evidence that HBC722 itself is driving an outflow. The non-detection of HBC722 in the 1.3 mm continuum observations suggests an upper limit of 0.02 solar masses for the mass of the circumstellar disk. This limit is consistent with typical T Tauri disks and with a disk that provides sufficient mass to power the burst.