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

Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, Scheinerstraße 1, 81679 München, Germany
e-mail: ohlendorf@usm.uni-muenchen.de

Received: 29 September 2011
Accepted: 19 January 2012

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° × 2°) Spitzer IRAC mosaics of the Carina Nebula and performed a spatially complete search for objects with excesses in the 4.5  μm 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_⊙ and  ~10   M_⊙ that are surrounded by circumstellar disks and embedded in circumstellar envelopes.

Conclusions. The estimated protostar masses  ≤10  M_⊙ 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.