Identifying the outflow driving sources in Orion-KL

TL;DR

This study combines molecular line observations to identify potential outflow driving sources in Orion-KL, suggesting SMA1 as the driver of a high-velocity outflow and source I for a low-velocity outflow, highlighting their characteristics.

Contribution

It provides new observational evidence linking SMA1 to a high-velocity outflow and refines the understanding of outflow sources in Orion-KL.

Findings

SMA1 may drive the high-velocity outflow.

Source I is likely responsible for the low-velocity outflow.

Outflow dynamical timescale is approximately 10^3 years.

Abstract

The enigmatic outflows of the Orion-KL region have raised discussions about their potential driving sources for several decades. Here, we present C18O(2-1) observations combined from the Submillimeter Array and the IRAM30m telescope. The molecular gas is associated on large scales with the famous northwest-southeast high-velocity outflow whereas the high-velocity gas on small spatial scales traces back to the recently identified submm source SMA1. Therefore, we infer that SMA1 may host the driving source of this outflow. Based on the previously published thermal and maser SiO data, source I is the prime candidate to drive the northeast-southwest low-velocity outflow. The source SMA1 is peculiar because it is only detected in several submm wavelength bands but neither in the infrared nor cm regime. We discuss that it may be a very young intermediate- to high-mass protostar. The estimated outflow masses are high whereas the dynamical time-scale of the outflow is short of the order 10^3yrs.