Volume 433, Number 3, April III 2005
|Page(s)||L49 - L52|
|Published online||29 March 2005|
Letter to the Editor
Detection of γ-ray lines from interstellar Fe by the high resolution spectrometer SPI
Centre d'Étude Spatiale des Rayonnements, BP 4346, 31028 Toulouse Cedex 4, France e-mail: Mike.Harris@cesr.fr
2 IASF, via E. Bassini 15, 20133 Milano, Italy
3 Max-Planck-Institut für extraterrestrische Physik, Postfach 1603, 85740 Garching, Germany
4 DSM/DAPNIA/SAp, CEA Saclay, 91191 Gif-sur-Yvette, France
Accepted: 23 February 2005
It is believed that core-collapse supernovae (CCSN), occurring at a rate ~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 γ-rays emitted when they β-decay. Here we report the detection of the 60Fe decay lines at 1173 keV and 1333 keV with fluxes 3.7 ± 1.1 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.
Key words: ISM: abundances / nucleosynthesis / gamma-rays: observations
© ESO, 2005
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