New Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Fe</mml:mi><mml:mprescripts /><mml:none /><mml:mn>60</mml:mn></mml:mmultiscripts></mml:math>Half-Life

Rugel, G.; Faestermann, T.; Knie, K.; Korschinek, G.; Poutivtsev, M.; Schumann, D.; Kivel, N.; Günther-Leopold, Ines; Weinreich, R.; Wohlmuther, M.

doi:10.1103/physrevlett.103.072502

Cited by 213 publications

(172 citation statements)

References 22 publications

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“…Some critical reaction rates, such as α(2α, γ) 12 C or 12 C(α, γ) 16 O, are known to have strong effects on the final yields (see for instance Tur et al 2009). As an illustration of the uncertainties on nuclear data, the half-life of 60 Fe was recently revised to 2.6 Myr, instead of the 1.5 Myr value we have been using throughout this work (Rugel et al 2009). In terms of predicted 1173/1332 keV lightcurves for the Cygnus complex, however, this longer lifetime simply implies an even lower emission at early times, still consistent with our upper limit (for a more quantitative analysis of the impact of the new 60 Fe lifetime, see Voss et al 2009).…”

Section: Sources Of Error/uncertaintymentioning

confidence: 99%

Predicted gamma-ray line emission from the Cygnus complex

Martin

Knödlseder

Meynet

et al. 2010

A&A

116

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Context. The Cygnus region harbours a huge complex of massive stars at a distance of 1.0-2.0 kpc from us. About 170 O stars are distributed over several OB associations, among which the Cyg OB2 cluster is by far the most important with about 100-120 O stars. These massive stars inject large quantities of radioactive nuclei into the interstellar medium, such as 26 Al and 60 Fe, and their gammaray line decay signals can provide insight into the physics of massive stars and core-collapse supernovae. Aims. Past studies of the nucleosynthesis activity of Cygnus have concluded that the level of 26 Al decay emission as deduced from CGRO/COMPTEL observations was a factor 2-3 above the predictions based on the theoretical yields available at that time and on the observed stellar content of the Cygnus region. We reevaluate the situation from new measurements of the gamma-ray decay fluxes with INTEGRAL/SPI (presented in a previous paper) and new predictions based on recently improved stellar models. Methods. We built a grid of nucleosynthesis yields from recent models of massive stars. Compared to previous works, our data include some of the effects of stellar rotation for the higher mass stars and a coherent estimate of the contribution from SNIb/c. We then developed a population synthesis code to predict the nucleosynthesis activity and corresponding decay fluxes of a given stellar population of massive stars. Results. The observed decay fluxes from the Cygnus complex are found to be consistent with the values predicted by population synthesis at solar metallicity; and yet, when extrapolated to the possible subsolar metallicity of the Cygnus complex, our predictions fail to account for the INTEGRAL/SPI measurements. The observed extent of the 1809 keV emission from Cygnus is found to be consistent with the result of a numerical simulation of the diffusion of 26 Al inside the superbubble blown by Cyg OB2. Conclusions. Our work indicates that the past dilemma regarding the gamma-ray line emission from Cygnus resulted from an overestimate of the 1809 keV flux of the Cygnus complex, combined with an underestimate of the nucleosynthesis yields. Our results illustrate the importance of stellar rotation and SNIb/c in the nucleosynthesis of 26 Al and 60 Fe. The effects of binarity and metallicity may also be necessary to account for the observations satisfactorily.

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Section: Sources Of Error/uncertaintymentioning

confidence: 99%

Predicted gamma-ray line emission from the Cygnus complex

Martin

Knödlseder

Meynet

et al. 2010

A&A

116

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“…1), as proposed in the supernova propagation and cloud enrichment (SPACE) model (Gounelle et al 2009). The calculations presented here are modified when taking the new (longer) mean lifetime of 60 Fe (Rugel et al 2009) into account, and adopting the SN yields of Woosley & Heger (2007) rather than a combination of yields as in Gounelle et al (2009).…”

Section: Updating the Space Modelmentioning

confidence: 99%

Solar system genealogy revealed by extinct short-lived radionuclides in meteorites

Gounelle

Meynet

2012

A&A

133

169

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Context. Little is known about the stellar environment and the genealogy of our solar system. Short-lived radionuclides (SLRs, mean lifetime τ shorter than 100 Myr) that were present in the solar protoplanetary disk 4.56 Gyr ago could potentially provide insight into that key aspect of our history, were their origin understood. Aims. Previous models failed to provide a reasonable explanation of the abundance of two key SLRs, 26 Al (τ 26 = 1.1 Myr) and 60 Fe (τ 60 = 3.7 Myr), at the birth of the solar system by requiring unlikely astrophysical conditions. Our aim is to propose a coherent and generic solution based on the most recent understanding of star-forming mechanisms. Methods. Iron-60 in the nascent solar system is shown to have been produced by a diversity of supernovae belonging to a first generation of stars in a giant molecular cloud. Aluminum-26 is delivered into a dense collected shell by a single massive star wind belonging to a second star generation. The Sun formed in the collected shell as part of a third stellar generation. Aluminum-26 yields used in our calculation are based on new rotating stellar models in which 26 Al is present in stellar winds during the star main sequence rather than during the Wolf-Rayet phase alone. Our scenario eventually constrains the time sequence of the formation of the two stellar generations that just preceded the solar system formation, along with the number of stars born in these two generations. Results. We propose a generic explanation for the past presence of SLRs in the nascent solar system, based on a collect-injection-andcollapse mechanism, occurring on a diversity of spatial/temporal scales. In that model, the presence of SLRs with a diversity of mean lifetimes in the solar protoplanetary disk is simply the fossilized record of sequential star formation within a hierarchical interstellar medium. We identify the genealogy of our solar system's three star generations earlier. In particular, we show that our Sun was born together with a few hundred stars in a dense collected shell situated at a distance of 5−10 pc from a parent massive star having a mass greater than about 30 solar masses and belonging to a cluster containing ∼1200 stars.

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“…Both reaction types are being investigated in laboratory experiments at the present time. Note that the β-decay lifetime of the 60 Fe isotope had been re-determined in 2008 [113], and found to be substantially longer, with (exponential) lifetime increased from 2.15 to 3.8 My (T 1/2 from 1.5 to 2.6 My). Another cause of lower Galaxy-wide 60 Fe glow could be that the explosion as a supernova does not occur throughout the entire range of stellar masses, but deviations from the standard initial-mass distribution on the high-mass end of massive stars ≥60 M , or 'islands of explodability' in that mass range occur.…”

Section: Al and 60 Fe From Massive Starsmentioning

confidence: 99%

“…In steady state, this brightness ratio thus constrains massive-star interiors globally for an average over all massive-star groups throughout the Galaxy. For stellar groups at specific ages, the steadystate assumption does not apply, however, and in particular the re-assessed decay time of 60 Fe of 3.8 My [112] (the formerly-used value was 2.2 My) must be taken into account for determinations of the isotope ratio (see discussion of specific regions below).…”

Section: Al and 60 Fe From Massive Starsmentioning

confidence: 99%

Cosmic Gamma-Ray Spectroscopy

Diehl

2013

Astronomical Review

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Penetrating gamma-rays require complex instrumentation for astronomical spectroscopy measurements of gamma-rays from cosmic sources. Multiple-interaction detectors in space combined with sophisticated postprocessing of detector events on ground have lead to a spectroscopy performance which is now capable to provide new astrophysical insights. Spectral signatures in the MeV regime originate from transitions in the nuclei of atoms (rather than in their electron shell). Nuclear transitions are stimulated by either radioactive decays or high-energy nuclear collisions such as with cosmic rays. Gamma-ray lines have been detected from radioactive isotopes produced in nuclear burning inside stars and supernovae, and from energetic-particle interactions in solar flares. Radioactive-decay gamma-rays from 56 Ni directly reflect the source of supernova light. 44 Ti is produced in core-collapse supernova interiors, and the paucity of corresponding 44 Ti gamma-ray line sources reflects the variety of dynamical conditions herein. 26 Al and 60 Fe are dispersed in interstellar space from massive-star nucleosynthesis over millions of years. Gamma-rays from their decay are measured in detail by gamma-ray telescopes, astrophysical interpretations reach from massive-star interiors to dynamical processes in the interstellar medium. Nuclear de-excitation gamma-ray lines have been found in solar-flare events, and convey information about energetic-particle production in these events, and their interaction in the solar atmosphere. The annihilation of positrons leads to another type of cosmic gamma-ray source. The characteristic annihilation gamma-rays at 511 keV have been measured long ago in solar flares, and now throughout the interstellar medium of our Milky Way galaxy. But now a puzzle has appeared, as a surprising predominance of the central bulge region was determined. This requires either new positron sources or transport processes not yet known to us. In this paper we discuss instrumentation and data processing for cosmic gamma-ray spectroscopy, and the astrophysical issues and insights from these measurements.

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New Measurement of theFe60Half-Life

Cited by 213 publications

References 22 publications

Predicted gamma-ray line emission from the Cygnus complex

Predicted gamma-ray line emission from the Cygnus complex

Solar system genealogy revealed by extinct short-lived radionuclides in meteorites

Cosmic Gamma-Ray Spectroscopy

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