# Probing ISM Structure in Trumpler 14 & Carina I Using The Stratospheric Terahertz Observatory 2

## TL;DR

This study uses the Stratospheric Terahertz Observatory 2 to map the [C II] emission in the Trumpler 14/Carina I region, revealing detailed gas structures, kinematics, and dispersal processes in this active star-forming area.

## Contribution

First detailed [C II] mapping of Trumpler 14/Carina I revealing gas dynamics and ionization fronts in this extreme star-forming region.

## Key findings

- [C II] emission correlates with CO cloud surfaces, tracing PDRs and ionization fronts.
- HII region luminosity exceeds PDR luminosity by 3.7 times along certain lines of sight.
- Dispersal timescale of GMCs in the region is estimated at 20-30 Myr.

## Abstract

We present observations of the Trumpler 14/Carina I region carried out using the Stratospheric Terahertz Observatory 2 (STO2). The Trumpler 14/Carina I region is in the west part of the Carina Nebula Complex, which is one of the most extreme star-forming regions in the Milky Way. We observed Trumpler 14/Carina I in the 158 $\mu$m transition of [C\,{\sc ii}] with a spatial resolution of 48$''$ and a velocity resolution of 0.17 km s$^{-1}$. The observations cover a 0.25$^\circ$ by 0.28$^\circ$ area with central position {\it l} = 297.34$^\circ$, {\it b} = -0.60$^\circ$. The kinematics show that bright [C\,{\sc ii}] structures are spatially and spectrally correlated with the surfaces of CO clouds, tracing the photodissociation region and ionization front of each molecular cloud. Along 7 lines of sight that traverse Tr 14 into the dark ridge to the southwest, we find that the [C\,{\sc ii}] luminosity from the HII region is 3.7 times that from the PDR. In same los we find in the PDRs an average ratio of 1:4.1:5.6 for the mass in atomic gas:dark-CO gas: molecular gas traced by CO. Comparing multiple gas tracers including HI 21cm, [C\,{\sc ii}], CO, and radio recombination lines, we find that the HII regions of the Carina Nebula Complex are well-described as HII regions with one-side freely expanding towards us, consistent with the champagne model of ionized gas evolution. The dispersal of the GMC in this region is dominated by EUV photoevaporation; the dispersal timescale is 20-30 Myr.