Article

New estimates of the contribution of Wolf-Rayet stellar winds to the Galactic 26Al

Vrije Universiteit Brussel, Bruxelles, Brussels Capital, Belgium
Astronomy and Astrophysics (Impact Factor: 4.48). 01/2005; 429(2). DOI: 10.1051/0004-6361:20041757
Source: OAI

ABSTRACT 12 pages, 8 figures.-- arXiv:0409580 astro-ph pre-print supplied.-- Final full-text version of the paper available at: http://dx.doi.org/10.1051/0004-6361:20041757. SIMBAD Objects associated to the paper available at: http://simbad.u-strasbg.fr/simbo.pl?bibcode=2005A%26A...429..613P. We present new yields of 26Al from Wolf-Rayet stellar winds based on rotating stellar models which account well for numerous observed properties of massive stars. We study the impacts on the yields of a change of initial mass, metallicity and initial rotation velocity. We also consider the effects of a change of mass loss rates during the Wolf-Rayet phase. We show that for surface rotation velocities during the core H-burning phase matching to the observed ones, the quantity of 26Al ejected by a star of a given initial mass and metallicity is roughly doubled when the effects of rotation are taken into account. The metallicity dependence of the yield is, on the other hand, very similar to that obtained from non-rotating models. We estimate that at least about 20% to 50% (e.g. ∼0.6-1.4 M_O) of the live 26Al detected in the Milky-Way originates from Wolf-Rayet stellar winds. We show the importance of a good knowledge of the present metallicity gradient and star formation rate in our galaxy for modeling both the variation of the 26Al surface density with the galactocentric distance and the global contribution of the Wolf-Rayet stellar winds to the present galactic mass of 26Al. A. Palacios acknowledges financial support from ESA PRODEX fellowship no 90069. Peer reviewed

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    • "While the general shape of the emission profiles is preserved, there are obviously large differences, changing the integrated emission profile of a stellar population significantly. Fig. 2. Time profile of the emission of 26 Al from stars of three masses (30, 50 and 90 M ⊙ ), using the code of Plüschke (2000), and the updated code (dotted lines), using new theoretical models (Meynet & Maeder, 2005; Palacios et al., 2005; Limongi & Chieffi, 2006) (solid lines). "
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    • "The population synthesis code uses a new library of stellar models [18] [21], with which it is possible to investigate the effects of stellar rotation. Newer models of the stellar winds from O and WR stars [20] [27] [28] are important, both for the 26 Al emission, as well as for the mechanical energy deposited in the interstellar medium. "
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    ABSTRACT: It is believed that core-collapse supernovae (CCSN), occurring at a rate about once per century, have seeded the interstellar medium with long-lived radioisotopes such as 60Fe (half-life 1.5 Myr), which can be detected by the gamma rays emitted when they beta-decay. Here we report the detection of the 60Fe decay lines at 1173 keV and 1333 keV with fluxes 3.7 +/- 1.1 x 10(-5) ph cm(-2) s(-1) per line, in spectra taken by the SPI spectrometer on board INTEGRAL during its first year. The same analysis applied to the 1809 keV line of 26Al yielded a line flux ratio 60Fe/26Al = 0.11 +/- 0.03. This supports the hypothesis that there is an extra source of 26Al in addition to CCSN. Comment: 4pp., 5 Figs., accepted by Astronomy & Astrophysics (letter), ref.'s comments included
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