Discovering young stars in the Gum 31 region with infrared observations

Abstract

Context. The Gum 31 bubble, which contains the stellar cluster NGC 3324, is a poorly studied young region close to the Carina Nebula. Aims. We are aiming to characterise the young stellar and protostellar population in and around Gum 31 and to investigate the starformation process in this region. Methods. We identified candidate young stellar objects from Spitzer, WISE, and Herschel data. Combining these, we analysed the spectral energy distributions of the candidate young stellar objects. With density and temperature maps obtained from Herschel data and comparisons to a collect-and-collapse scenario for the region we are able to further constrain the characteristics of the region as a whole. Results. We find 661 candidate young stellar objects from WISE data; 91 protostar candidates are detected through Herschel observations in a 1.0• × 1.1• area. Most of these objects are found in small clusters or are well aligned with the H II bubble. We also identify the sources of Herbig-Haro jets. The infrared morphology of the region suggests that it is part of the larger Carina Nebula complex. Conclusions. The location of the candidate young stellar objects on the rim of the H II bubble is suggestive of their being triggered according to a collect-and-collapse scenario, which agrees well with the observed parameters of the region. Some candidate young stellar objects are found in the heads of pillars, which indicates radiative triggering of star formation. All in all, we find evidence that in the region different mechanisms of triggered star formation are at work. Correcting the number of candidate young stellar objects for contamination, we find ∼600 young stellar objects in Gum 31 above our completeness limit of about 1 M . Extrapolating the initial mass function down to 0.1 M , we estimate a total population of ∼5000 young stars for the region.

The VISTA Carina Nebula Survey

“…Cluster G286.38-0.26 Figure 7 shows the VISTA view of the cluster G286.38-0.26, which is partly embedded in a cloud clump in the southern edge of the dust bubble around Gum 31. The bluish and reddish stars trace the different populations of stars seen in front of the clump and embedded in the clump, as discussed in Ohlendorf et al (2013). A multiwavelength (optical to FIR) comparison of this cluster can be seen in Fig.…”

“…A multiwavelength (optical to FIR) comparison of this cluster can be seen in Fig. 12 of Ohlendorf et al (2013).…”

The VISTA Carina Nebula Survey

“…The combination of the NIR data (J,H, and K s -band) of the VCNS with the Spitzer MIR data (3.6 μm, 4.5 μm, 5.8 μm, and 8.0 μm; Ohlendorf et al 2013) revealed new insight into the spatial distribution and the clustering properties of the young stellar populations in the CNC. The area covered simultaneously by both surveys is ∼5.30 deg 2 .…”

“…PAH emission from diffuse structures close to point sources can thus adulterate the photometric flux measurements in the IRAC bands 1, 3, (Bressan et al 2012) and the blue asterisks show the locus of the red supergiants, TP-AGBs, and upperRGBs produced with the dusty models. We also give the typical uncertainties of the photometry from Preibisch et al (2014) for the VISTA data and from Ohlendorf et al (2013) for the [4.5]-band. The color bar shows the number of objects per bin (bin size = 0.02 mag × 0.02 mag).…”

A multiwavelength investigation of the H ii region S311: young stellar population and star formation

“…Recent simulations of this process are shown by Hosokawa & Inutsuka (2005, 2006 and Dale et al (2007). An observational signature of this process is the presence of a dense layer and (more or less regularly spaced) massive condensations adjacent to the H ii region (e.g., Deharveng et al 2003Deharveng et al , 2005Zavagno et al 2006;Liu et al 2015;Pirogov et al 2013;Ohlendorf et al 2013). If the IF/SF encounters pre-existing denser region, it compresses them to induce star formation.…”