Young stars in the Carina Nebula Complex

The Carina Nebula Complex is known to be an active star-formation region. This work presents a large catalogue of point-like sources assembled from archive data of the Infrared Array Camera (IRAC) onboard the Spitzer Space Telescope. This catalogue covers a region of 2.3 deg × 3.0 deg, which makes it the most extendended mid-infrared survey undertaken of the Carina Nebula Complex to date. From the catalogue a subsample of candidate young stellar objects is extracted utilising the fact that young stellar objects exhibit typical mid-infrared excesses. These catalogues are employed to characterise the young stellar population of the Carina Nebula Complex. Using them, it was possible to identify three new extended green objects and five compact green objects and find the probable sources for 28 further objects connected with jets emitted from young stars, such as molecular hydrogen emission-line objects and Herbig-Haro jets. For 17 of them, observational data from the near-infrared (from HAWK-I and 2MASS) to the far-infrared (from the Herschel Space Observatory) could be collected and their spectral energy distributions fitted. From the fit parameters, stellar characteristics such as stellar and disk masses could be estimated. No young stellar objects with masses above 10 M_sol could be evidenced, pointing towards an intermediate-mass population currently forming. It could be shown that the Gum 31 region on the outer periphery of the Carina Nebula Complex is not only part of the complex but also an important centre of star formation. A large sample of candidate young stellar object was obtained from the WISE All-Sky Data Release, which allowed a detailed comparison with both the candidate young stellar objects from the IRAC catalogue and those identified from Herschel observations. Evidence could be found that two modes of triggered star formation are going on in the HII region: Young stellar objects are found in and in front of dust pillars, which is an indicator of radiative triggering, and a ‘collect and collapse’ model of the region was shown to produce results in agreement with the observations. An objective and large-scale search for clusters of young stellar objects in the complex was performed using a nearest-neighbour algorithm. This search derived 22 clusters not described before. Nine of those are new detections in the fields of previous studies of clusters while the majority are found in fields surveyed for clusters for the first time here. Clusters are also found in agreement with previous studies where study fields overlap, thus corroborating the validity of the study. It is found that ∼40% of the young stellar objects in the Carina Nebula Complex occur in clusters while up to 60% are part of a distributed population. A total population for the 2.3 deg × 3.0 deg study field of ∼200 000 young stars is estimated