Jet-driving protostars identified from infrared observations of the Carina Nebula complex

TL;DR

This study identifies jet-driving protostars in the Carina Nebula using infrared data, revealing that current star formation mainly produces low- to intermediate-mass stars near cloud surfaces.

Contribution

It presents a large-scale infrared survey combined with radiative transfer modeling to identify and characterize protostars driving jets in the Carina Nebula, a high-feedback star-forming region.

Findings

Protostars have masses between ~1 and 10 solar masses.

Star formation in Carina is mainly producing low- and intermediate-mass stars.

More optical jets than infrared indicate star formation near cloud surfaces.

Abstract

Aims: Jets are excellent signposts for very young embedded protostars, so we want to identify jet-driving protostars as a tracer of the currently forming generation of stars in the Carina Nebula, which is one of the most massive galactic star-forming regions and which is characterised by particularly high levels of massive-star feedback on the surrounding clouds. Methods: We used archive data to construct large (> 2 deg x 2 deg) Spitzer IRAC mosaics of the Carina Nebula and performed a spatially complete search for objects with excesses in the 4.5 micron band, typical of shock-excited molecular hydrogen emission. We also identified the mid-infrared point sources that are the likely drivers of previously discovered Herbig-Haro jets and molecular hydrogen emission line objects. We combined the Spitzer photometry with our recent Herschel far-infrared data to construct the spectral energy distributions, and used the Robitaille radiative-transfer modelling tool to infer the properties of the objects. Results: The radiative-transfer modelling suggests that the jet sources are protostars with masses between ~1 M_sol and ~10 M_sol that are surrounded by circumstellar disks and embedded in circumstellar envelopes. Conclusions: The estimated protostar masses < 10 M_sol suggest that the current star-formation activity in the Carina Nebula is restricted to low- and intermediate-mass stars. More optical than infrared jets can be observed, indicating that star formation predominantly takes place close to the surfaces of clouds.