Astronomy & Astrophysics
We study the populations of massive stars in the Carina region and their energetic feedback and ejection of 26Al. Methods. We did a census of the stellar populations in young stellar clusters within a few degrees of the Carina nebula. For each star we estimated the mass, based on the spectral type and the host cluster age. We used population synthesis to calculate the energetic feedback and ejection of 26Al from the winds of the massive stars and their supernova explosions. We used 7 years of INTEGRAL observations to measure the 26Al signal from the region. Results. The INTEGRAL 26Al signal is not signiﬁcant with a best-ﬁt value of ∼1.5 ±1.0 ×10^−5 ph cm^−2 s^−1, approximately half of the published Compton Gamma Ray Observatory (CGRO) result, but in agreement with the latest CGRO estimates. Our analysis of the stellar populations in the young clusters leads to an expected signal of ∼half the observed value, but the results are consistent within 2σ. We ﬁnd that the fraction of 26Al ejected in Wolf-Rayet winds is high, and the observed signal is unlikely to be caused by 26Al ejected in supernovae alone, indicating a strong wind ejection of 26Al. Due to the lack of prominent O stars, regions with ages > 10 Myr are often neglected in studies of OB associations. We ﬁnd that in the Carina region such clusters contribute signiﬁcantly to the stellar mass and the energetics of the region.
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