The Spitzer c2d Survey of Nearby Dense Cores XI : Infrared and Submillimeter Observations of CB130

TL;DR

This study combines infrared and submillimeter observations to analyze the physical and chemical properties of the CB130 dense cores, revealing episodic accretion as a key factor in the low luminosity of the Class 0 object CB130-1.

Contribution

It introduces chemical evolution models with episodic accretion to explain low luminosity and molecular line features in a dense core, advancing understanding of protostellar evolution.

Findings

CB130-1 has low luminosity (0.14-0.16 L_sun) consistent with episodic accretion.

Chemical models with episodic accretion better fit observed molecular lines and ice features.

Low luminosity is due to a quiescent phase between accretion bursts, not a first hydrostatic core stage.

Abstract

We present new observations of the CB130 region, composed of three separate cores. Using the \textit{Spitzer Space Telescope} we detected a Class 0 and a Class II object in one of these, CB130-1. The observed photometric data from \textit{Spitzer} and ground-based telescopes are used to establish the physical parameters of the Class 0 object. SED fitting with a radiative transfer model shows that the luminosity of the Class 0 object is 0.14 $-$ 0.16 L$_{\odot}$, which is a low luminosity for a protostellar object. In order to constrain the chemical characteristics of the core having the low luminosity object, we compare our molecular line observations to models of lines including abundance variations. We tested both ad hoc step function abundance models and a series of self-consistent chemical evolution models. In the chemical evolution models, we consider a continuous accretion model and an episodic accretion model to explore how variable luminosity affects the chemistry. The step function abundance models can match observed lines reasonably well. The best fitting chemical evolution model requires episodic accretion and the formation of CO$_2$ ice from CO ice during the low luminosity periods. This process removes C from the gas phase, providing a much improved fit to the observed gas-phase molecular lines and the CO$_2$ ice absorption feature. Based on the chemical model result, the low luminosity of CB130-1 is explained better as a quiescent stage between episodic accretion bursts rather than being at the first hydrostatic core stage.