Nearby Supernova Explosion Research Articles

60Fe: A Heat Source for Planetary Differentiation from a Nearby Supernova Explosion

From a sample of the Semarkona (LL 3.0) ordinary chondrite we report the in situ discovery of 60Ni isotopic anomalies attributable to the decay of short-lived 60Fe (half-life 1.5 Myr) in the mineral phases troilite (FeS) and magnetite (Fe3O4). The troilite shows a 60Ni excesses of up to ~100 parts per thousand (‰) relative to its solar isotopic abundance. A positive correlation between 60Ni excesses and 56Fe/58Ni ratios provides evidence for live 60Fe in the early solar system. The inferred 60Fe/56Fe ratio of (0.92 ± 0.24) × 10-6 is the highest measured in any meteorite sample so far. This ratio is higher than predictions for production within asymptotic giant branch stars, but falls within the range expected for a Type II supernova source. This result is strongly suggestive of injection of freshly synthesized 60Fe into the nascent solar nebula by a nearby supernova explosion. Such a high abundance of 60Fe will exclude irradiation with solar energetic particles as the sole mechanism responsible for the production of short-lived radionuclides. It further shows that the decay of 60Fe was an important heat source for early planetary melting and differentiation and for keeping asteroids thermally active for much longer than would be possible from the decay of 26Al alone.

F60eAnomaly in a Deep-Sea Manganese Crust and Implications for a Nearby Supernova Source

A nearby supernova (SN) explosion in the past can be confirmed by the detection of radioisotopes on Earth that were produced and ejected by the SN. We have now measured a well resolved time profile of the 60Fe concentration in a deep-sea ferromanganese crust and found a highly significant increase 2.8 Myr ago. The amount of 60Fe is compatible with the deposition of ejecta from a SN at a distance of a few 10 pc. The well defined time of the SN explosion makes it possible to search for plausible correlations with other events in Earth's history.

Gravitational waves from a pulsar kick caused by neutrino conversions

It has been suggested that the observed pulsar velocities are caused by an asymmetric neutrino emission from a hot neutron star during the first seconds after the supernova collapse. We calculate the magnitude of gravitational waves produced by the asymmetries in the emission of neutrinos. The resulting periodic gravitational waves may be detectable by LIGO and LISA in the event of a nearby supernova explosion.

Evidence for nearby supernova explosions.

Supernova (SN) explosions are one of the most energetic---and potentially lethal---phenomena in the Universe. We show that the Scorpius-Centaurus OB association, a group of young stars currently located at approximately 130 pc from the Sun, has generated 20 SN explosions during the last 11 Myr, some of them probably as close as 40 pc to our planet. The deposition on Earth of (60)Fe atoms produced by these explosions can explain the recent measurements of an excess of this isotope in deep ocean crust samples. We propose that approximately 2 Myr ago, one of the SNe exploded close enough to Earth to seriously damage the ozone layer, provoking or contributing to the Pliocene-Pleistocene boundary marine extinction.

The Origin of the Local Bubble

The Sun is located in a low-density region of the interstellar medium partially filled with hot gas that is the likely result of several nearby supernova explosions within the last 10 Myr. Here we use astrometric data to show that part of the Scorpius-Centaurus OB association was located closer to the present position of the Sun 5-7 Myr ago than today. Evolutionary synthesis models indicate that the association must have experienced ~20 supernova explosions in the last 10-12 Myr, a prediction that is supported by the detection of four or five runaway stars escaping from it. The ~6 SNe produced by the Lower Centaurus Crux subgroup are likely responsible for the creation of the Local Bubble.

Supernova constraints on neutrino mass and mixing

In this article I review the constraints on neutrino mass and mixing coming from type-II supernovae. The bounds obtained on these parameters from shock reheating, r-process nucleosynthesis and from SN1987A are discussed. Given the current constraints on neutrino mass and mixing the effect of oscillations of neutrinos from a nearby supernova explosion in future detectors will also be discussed.

Geological Isotope Anomalies as Signatures of Nearby Supernovae

Nearby supernova explosions may cause geological isotope anomalies via the direct deposition of debris or by cosmic-ray spallation in the earth’s atmosphere. We estimate the mass of material deposited terrestrially by these two mechanisms, showing the dependence on the supernova distance. A number of radioactive isotopes are identified as possible diagnostic tools, such as Be, Al, Cl, Mn, Fe, and Ni, as well as the longer-lived I, Sm, and Pu. We discuss whether the 35 and 60 kyr-old Be anomalies observed in the Vostok antarctic ice cores could be due to supernova explosions. Combining our estimates for matter deposition with results of recent nucleosynthesis yields, we calculate the expected signal from nearby supernovae using ice cores back to O(300) kyr ago, and we discuss using deep ocean sediments back to several hundred Myr. In particular, we examine the prospects for identifying isotope anomalies due to the Geminga supernova explosion, and signatures of the possibility that supernovae might have caused one or more biological mass extinctions. Subject headings: nuclear reactions, nucleosynthesis: abundances — supernovae: general — pulsars: individual (Geminga) also Institut d’Astrophysique de Paris, 98 bis Boulevard Arago Paris 75014, France also NASA/Fermilab Astrophysics Center, FNAL Box 500 Batavia, IL, 60510

Could a nearby supernova explosion have caused a mass extinction?

We examine the possibility that a nearby supernova explosion could have caused one or more of the mass extinctions identified by paleontologists. We discuss the possible rate of such events in the light of the recent suggested identification of Geminga as a supernova remnant less than 100 parsec (pc) away and the discovery of a millisecond pulsar about 150 pc away and observations of SN 1987A. The fluxes of gamma-radiation and charged cosmic rays on the Earth are estimated, and their effects on the Earth's ozone layer are discussed. A supernova explosion of the order of 10 pc away could be expected as often as every few hundred million years and could destroy the ozone layer for hundreds of years, letting in potentially lethal solar ultraviolet radiation. In addition to effects on land ecology, this could entail mass destruction of plankton and reef communities, with disastrous consequences for marine life as well. A supernova extinction should be distinguishable from a meteorite impact such as the one that presumably killed the dinosaurs at the "KT boundary." The recent argument that the KT event was exceedingly large and thus quite rare supports the need for other catastrophic events.

Implications of the solar neutrino experiments

Abstract The recent results from the KAMIOKANDE II and BAKSAN solar neutrino experiments, if correct, imply that lepton flavour is not conserved. The Mikheyev-Smirnov-Wolfenstein (MSW) solution to the solar neutrino problem, which was first exposed by the HOMESTAKE Cl experiment, fully explains also these results if the electron neutrino is mixed with the muon neutrino or the tau neutrino with mixing parameters Δm 2 ∼ 10 −6 cV −2 and sin 2 2 θ ∼ 4 × 10 −2 . This MSW solution can be tested with the new generation of solar neutrino experiments which will be able to detect both the predicted distortion of the spectrum of 8 B solar v e 's and the “missing” v e 's that appear as v μ 's or v τ 's . Further evidence may be obtained from the day-night effect and from the flavour content of the neutronization burst from the birth of a neutron star in a nearby supernova. Moreover, the MSW solution combined with the seesaw mechanism for generating neutrino masses further suggests m v e ∼ 10 −8 eV , m v μ ∼ 10 −3 cV , m v τ ∼ 10 cV , and sin 2 2 θ ∼ 4 × 10 −2 for v μ v τ mixing. These predictions can be tested by previously proposed neutrino oscillation experiments at accelerators and by detecting neutrinos from a nearby supernova explosion. A tau neutrino with m v τ ∼ 10 eV can account for most of the dark matter in the Universe and is a viable candidate for the hot dark matter scenario of the formation of large scale structure in the Universe.

Effect of nearby supernova explosions on atmospheric ozone

WE have calculated the probable effects of a nearby supernova event on the ozone layer. We find that the effects are significant and long lasting, but are relatively rare at the location of the Earth in the Galaxy.

Possible Consequences of Nearby Supernova Explosions for Atmospheric Ozone and Terrestrial Life

Hard x-ray pulses or increased cosmic radiation originating in nearby supernova explosions may be capable of temporarily removing most of the earth's atmospheric ozone cover even when direct radiation effects at the earth's surface are negligible. Consequently, terrestrial life may be subject to relatively huge solar ultraviolet fluxes every few hundred million years.

Sea Sediments, Cosmic Rays, and Pulsars

Measured variations in 10Be and 26Al in deep sea sediments may result from increases in the local cosmic ray intensities produced by a nearby supernova explosion.

The Abundances of Boron, Beryllium, and Lithium in the Peculiar a Star Kappa CANCRI

view Abstract Citations (19) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Abundances of Boron, Beryllium, and Lithium in the Peculiar a Star Kappa CANCRI Boesgaard, Ann Merchant ; Heacox, William D. Abstract A weak feature in the spectrum of K Cnc is attributed to B U, and the abundance B/H is found to be 2 X i0- . The abundance of Be is determined to be Be/H 2.5 X 1O- . Wavelength measurements indicate that there is little, if any, 7Be or 10Be. An upper limit of Li/H <4.5 >c l0- has been determined. The galactic-cosmic-ray origin of the light elements is insufficient to account for the Be and B abundances by 2 to 3 orders of magnitude and for the B/Be ratio of 75. It is suggested that a nearby supernova explosion or spallation reactions on the surface of this Mn-Hg Ap star could account for the observed abundance ratios. Subject headings:abundances, stellar - peculiar A stars Publication: The Astrophysical Journal Pub Date: October 1973 DOI: 10.1086/181314 Bibcode: 1973ApJ...185L..27B full text sources ADS | data products SIMBAD (1)

Supernovae and the Extinction of the Dinosaurs

WE wish to suggest that a nearby supernova explosion might produce climatic effects so drastic as to cause the extinction of many animals, including the dinosaurs. Earlier discussions of this topic1,2 focused on the radiation doses to be expected as a result of the interaction of high-energy cosmic rays and γ-rays with the atmosphere. Reasonable estimates of the parameters involved implied doses which may account for some of the patterns of mass extinction observed in the geological record.