Jet-driving protostars identified from infrared observations of the Carina Nebula complex⋆
H. Ohlendorf, T. Preibisch, B. Gaczkowski, T. Ratzka, R. Grellmann and A. F. McLeod
Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, Scheinerstraße 1, 81679 München, Germany
Received: 29 September 2011
Accepted: 19 January 2012
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.
Key words: ISM: clouds / stars: formation / ISM: jets and outflows / stars: protostars / Herbig-Haro objects
This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, and on data collected by Herschel, an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
© ESO, 2012