Near-Infrared High-Resolution Imaging Polarimetry of FU Ori-Type Objects: Towards A Unified Scheme for Low-Mass Protostellar Evolution

TL;DR

This study uses high-resolution near-infrared polarimetry to observe circumstellar dust around FU Ori-type objects, revealing diverse morphologies linked to gravitational instability and outburst mechanisms, supporting a unified model of low-mass protostellar evolution.

Contribution

It provides detailed high-resolution imaging of FU Ori objects, linking their complex structures to disk fragmentation and outburst processes, advancing understanding of low-mass star formation.

Findings

Diverse polarized light morphologies observed around FU Ori objects.

Structures attributed to gravitational instability, ejections, winds, or companions.

Supports the scenario that FUor outbursts are caused by disk fragmentation.

Abstract

We present near-IR imaging polarimetry of five classical FU Ori-type objects (FU Ori, V1057 Cyg, V1515 Cyg, V1735 Cyg, Z CMa) with a $\sim$0\farcs1 resolution observed using HiCIAO+AO188 at Subaru Telescope. We observed scattered light associated with circumstellar dust around four of them (i.e., all but V1515 Cyg). Their polarized intensity distribution shows a variety of morphologies with arms, tails or streams, spikes and fragmented distributions, many of which were reported in our previous paper. The morphologies of these reflection nebulae significantly differ from many other normal young stellar objects (Class I-II objects). These structures are attributed to gravitationally unstable disks, trails of clump ejections, dust blown by a wind or a jet, and a stellar companion. We can consistently explain our results with the scenario that their accretion outbursts (FUor outbursts) are triggered by gravitationally fragmenting disks, and with the hypothesis that many low-mass young stellar objects experience such outbursts.