Energetic feedback and ²⁶Al from massive stars and their supernovae in the Carina region

¹ Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
e-mail: rvoss@science.ru.nl
² Institut de Planétologie et d’Astrophysique de Grenoble, BP 53, 38041 Grenoble Cedex 9, France
³ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
⁴ Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK
⁵ Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978, USA
⁶ Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany

Received: 5 October 2011
Accepted: 3 January 2012

Abstract

Aims. 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.