2MASS J17112318-2724315: A Deeply-Embedded Low-Mass Protostellar System in the B59 Molecular Cloud

TL;DR

This study presents near-infrared observations and modeling of a deeply-embedded low-mass protostellar system in B59, revealing a Class I protostar with outflow features, variability, and unique spectral absorption characteristics.

Contribution

It provides detailed observational data and modeling of the protostellar system, including detection of a nearby companion, spectral features, and variability analysis, advancing understanding of early low-mass star formation.

Findings

Detection of a low-luminosity Class I protostar with an estimated age of 0.1-1 Myr.

Observation of Ks-band variability linked to infall rate changes.

Identification of a rare 11.3 micron absorption feature correlated with water ice.

Abstract

We present near-infrared observations of the low-mass deeply-embedded Class 0/I system 2MASS J17112318-2724315 (2M171123) in the B59 molecular cloud. Bright scattered light nebulosity is observed towards this source in the Ks images, that seems to trace the edges of an outflow cavity. We report the detection of a low-luminosity protostar 2M17112255-27243448 (2M17112255) that lies 8" (~1000 AU) from 2M171123. This is a Class I system, as indicated by its 2-8 micron slope and IRAC colors, with an estimated internal luminosity of ~0.3Lsun. We estimate a mass of ~0.12-0.25 Msun for this source, at an age of 0.1-1Myr. Also presented is detailed modeling of the 2M171123 system. The best-fit parameters indicate a large envelope density of the order of ~10^(-13) g cm^(-3), and an intermediate inclination between 53 and 59deg. The observed Ks-band variability for this system could be explained by slight variability in the mass infall rate between 2.5E-5 and 1.8E-5 Msun/yr. The protostar 2M171123 exhibits a rarely observed absorption feature near 11.3 micron within its 10 micron silicate band. We find a strong correlation between the strength in this 11.3 micron 'edge' and the H2O-ice column density, indicating the origin of this feature in the thickness of the ice mantle over the silicate grains.