AKARI near-infrared spectroscopy of the extended green object G318.05+0.09: Detection of CO fundamental ro-vibrational emission

TL;DR

This study uses AKARI near-infrared spectroscopy to analyze an extended green object, revealing a massive young stellar object and detecting CO fundamental ro-vibrational emission indicative of high-velocity outflows or supernova ejecta.

Contribution

First detection of CO fundamental ro-vibrational emission in an extended green object, providing insights into outflows and supernova remnants.

Findings

Identification of a massive young stellar object near an HII region.

Detection of blue-shifted CO emission at high velocities.

Evidence suggesting outflow activity or supernova ejecta.

Abstract

We present the results of near-infrared (2.5--5.4um) long-slit spectroscopy of the extended green object (EGO) G318.05+0.09 with AKARI. Two distinct sources are found in the slit. The brighter source has strong red continuum emission with H2O ice, CO2 ice, and CO gas and ice absorption features at 3.0, 4.25um, 4.67um, respectively, while the other greenish object shows peculiar emission that has double peaks at around 4.5 and 4.7um. The former source is located close to the ultra compact HII region IRAS 14498-5856 and is identified as an embedded massive young stellar object. The spectrum of the latter source can be interpreted by blue-shifted (-3000 ~ -6000km/s) optically-thin emission of the fundamental ro-vibrational transitions (v=1-0) of CO molecules with temperatures of 12000--3700K without noticeable H2 and HI emission. We discuss the nature of this source in terms of outflow associated with the young stellar object and supernova ejecta associated with a supernova remnant.