# The CARMA-NRO Orion Survey: Core Emergence and Kinematics in the Orion A Cloud

## TL;DR

This study investigates the formation, density thresholds, and kinematics of cores in the Orion A cloud, revealing a universal star formation threshold, denser gas production compared to other clouds, and bound, oscillatory core motions within the filament.

## Contribution

It provides new insights into core formation thresholds, dense gas production, and core kinematics in Orion A, with implications for star formation universality and cloud dynamics.

## Key findings

- Universal star formation extinction threshold around A_V~7 mag.
- Orion A produces more dense gas than similar clouds.
- Cores exhibit bound, sub-sonic, oscillatory motions.

## Abstract

We have investigated the formation and kinematics of sub-mm continuum cores in the Orion A molecular cloud. A comparison between sub-mm continuum and near infrared extinction shows a continuum core detection threshold of $A_V\sim$ 5-10 mag. The threshold is similar to the star formation extinction threshold of $A_V\sim$ 7 mag proposed by recent work, suggesting a universal star formation extinction threshold among clouds within 500 pc to the Sun. A comparison between the Orion A cloud and a massive infrared dark cloud G28.37+0.07 indicates that Orion A produces more dense gas within the extinction range 15 mag $\lesssim A_V \lesssim$ 60 mag. Using data from the CARMA-NRO Orion Survey, we find that dense cores in the integral-shaped filament (ISF) show sub-sonic core-to-envelope velocity dispersion that is significantly less than the local envelope line dispersion, similar to what has been found in nearby clouds. Dynamical analysis indicates that the cores are bound to the ISF. An oscillatory core-to-envelope motion is detected along the ISF. Its origin is to be further explored.