High-resolution polarimetry of Parsamian 21: revealing the structure of an edge-on FU Ori disc

TL;DR

This study uses high-resolution near-infrared polarimetry and archival data to analyze Parsamian 21, revealing it as an FU Orionis-type star with a flat, edge-on circumstellar disc and envelope, providing insights into its structure and evolutionary stage.

Contribution

First high-resolution polarimetric observations of Parsamian 21 combined with archival data, revealing its disc and envelope structure and confirming its FU Orionis nature.

Findings

Parsmanian 21 is likely an FU Orionis-type object.

The object has a flat, edge-on circumstellar disc from 48 to 360 AU.

The spectral energy distribution can be modeled with a disc and envelope.

Abstract

We present the first high spatial resolution near-infrared direct and polarimetric observations of Parsamian 21, obtained with the VLT/NACO instrument. We complemented these measurements with archival infrared observations, such as HST/WFPC2 imaging, HST/NICMOS polarimetry, Spitzer IRAC and MIPS photometry, Spitzer IRS spectroscopy as well as ISO photometry. Our main conclusions are the following: (1) we argue that Parsamian 21 is probably an FU Orionis-type object; (2) Parsamian 21 is not associated with any rich cluster of young stars; (3) our measurements reveal a circumstellar envelope, a polar cavity and an edge-on disc; the disc seems to be geometrically flat and extends from approximately 48 to 360 AU from the star; (4) the SED can be reproduced with a simple model of a circumstellar disc and an envelope; (5) within the framework of an evolutionary sequence of FUors proposed by Green et al. (2006) and Quanz et al. (2007), Parsamian 21 can be classified as an intermediate-aged object.