Volume 394, Number 2, November I 2002
|Page(s)||517 - 523|
|Section||Interstellar and circumstellar matter|
|Published online||15 October 2002|
COMPTEL upper limits for the Co γ-ray emission from SN1998bu
Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
2 FRM-II, Technische Universität München, Lichtenbergstr. 1, 85747 Garching, Germany
3 SRON Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
4 Space Science Center, University of New Hampshire, Durham, NH 03824, USA
5 Science Division, ESTEC, ESA, 2200 AG Noordwijk, The Netherlands
Corresponding author: R. Georgii, firstname.lastname@example.org
Accepted: 1 August 2002
Supernova 1998bu in the galaxy M 96 was observed by COMPTEL for a total of 88 days starting 17 days after the explosion. We searched for a signal in the 847 keV and 1238 keV lines of radioactive 56Co from this type Ia supernova. Using several different analysis methods, we did not detect SN1998bu. Our measurements should have been sensitive enough to detect 60Co gamma-rays as predicted from supernova models. Our flux limit is photons cm-2 s-1; this would correspond to 0.35 of ejected 56Ni, if SN1998bu were at a distance of 11.3 Mpc and transparent to MeV gamma rays for the period of our measurements. We discuss our measurements in the context of common supernova models, and conclude disfavoring a supernova event with large mixing and major parts of the freshly-generated radioactivity in outer layers.
Key words: stars: supernovae: individual: SN1998bu / gamma-rays: observations / nucleosynthesis
© ESO, 2002
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