scholarly journals r-Process Radioisotopes from Near-Earth Supernovae and Kilonovae

2021 ◽  
Vol 923 (2) ◽  
pp. 219
Author(s):  
Xilu Wang (王夕露) ◽  
Adam M. Clark ◽  
John Ellis ◽  
Adrienne F. Ertel ◽  
Brian D. Fields ◽  
...  
Keyword(s):  
Lunar Regolith ◽  
Deep Ocean ◽  
Solar Neighborhood ◽  
Mass Extinctions ◽  
Local Bubble ◽  
The Earth ◽  
Time Histories ◽  
History Of ◽  
R Process ◽  
Process Elements

Abstract The astrophysical sites where r-process elements are synthesized remain mysterious: it is clear that neutron star mergers (kilonovae (KNe)) contribute, and some classes of core-collapse supernovae (SNe) are also possible sources of at least the lighter r-process species. The discovery of 60Fe on the Earth and Moon implies that one or more astrophysical explosions have occurred near the Earth within the last few million years, probably SNe. Intriguingly, 244Pu has now been detected, mostly overlapping with 60Fe pulses. However, the 244Pu flux may extend to before 12 Myr ago, pointing to a different origin. Motivated by these observations and difficulties for r-process nucleosynthesis in SN models, we propose that ejecta from a KN enriched the giant molecular cloud that gave rise to the Local Bubble, where the Sun resides. Accelerator mass spectrometry (AMS) measurements of 244Pu and searches for other live isotopes could probe the origins of the r-process and the history of the solar neighborhood, including triggers for mass extinctions, e.g., that at the end of the Devonian epoch, motivating the calculations of the abundances of live r-process radioisotopes produced in SNe and KNe that we present here. Given the presence of 244Pu, other r-process species such as 93Zr, 107Pd, 129I, 135Cs, 182Hf, 236U, 237Np, and 247Cm should be present. Their abundances and well-resolved time histories could distinguish between the SN and KN scenarios, and we discuss prospects for their detection in deep-ocean deposits and the lunar regolith. We show that AMS 129I measurements in Fe–Mn crusts already constrain a possible nearby KN scenario.

scholarly journals Does the lunar regolith contain secrets of the Solar System? Using the Moon as a cosmic witness plate

2009 ◽  
Vol 5 (S264) ◽  
pp. 475-477 ◽  
Author(s):  
David S. McKay ◽  
Louise Riofrio ◽  
Bonnie L. Cooper
Keyword(s):  
Solar System ◽  
Lunar Regolith ◽  
Lunar Soil ◽  
The Moon ◽  
System A ◽  
The Earth ◽  
Radiation History ◽  
History Of ◽  
Time Capsule ◽  
The Impact

AbstractThe lunar regolith (soil) has recorded a history of the early Moon, the Earth, and the entire solar system. A major goal of the developing lunar exploration program should be to find and play back existing fragments of that tape. By playing back the lunar tape, we can uncover a record of planetary bombardment, as well as solar and stellar variability. The Moon can tell us much about our place in the solar system and in the Universe. The lunar regolith has likely recorded the original meteoritic bombardment of Earth and Moon, a violent cataclysm that may have peaked around 4 GY, and the less intense bombardment occurring since that time. Decrease in bombardment allowed life to develop on Earth. This impact history is preserved as megaregolith layers, ejecta layers, impact melt rocks, and ancient impact breccias. The impact history for the Earth and Moon possibly had profound effects on the origin and development of life. Life may have arrived via meteorite transport from a more quiet body, such as Mars. The solar system may have experienced bursts of severe radiation from the Sun, other stars or from unknown sources. The lunar regolith has also recorded a radiation history in the form of implanted and trapped solar wind and solar flare materials and radiation damage. The Moon can be considered as a giant tape recorder containing the history of the solar system. Lunar soil generated by small impacts will be found sandwiched between layers of basalt or pyroclastic deposits. This filling constitutes a buried time capsule that is likely to contain well-preserved ancient regolith. Study of such samples will show us how the solar system has evolved and changed over time. The lunar recording can provide detailed snapshots of specific portions of solar and stellar variability.

scholarly journals The Oldest Stars as Tracers of Heavy Element Formation at Early Epochs

2001 ◽  
Vol 204 ◽  
pp. 333-334 ◽  
Author(s):  
James W. Truran
Keyword(s):  
Star Formation ◽  
Theoretical Models ◽  
Elemental Abundance ◽  
Agb Stars ◽  
Lower Mass ◽  
Set Constraints ◽  
Abundance Patterns ◽  
History Of ◽  
R Process ◽  
Process Elements

Elemental abundance patterns in very metal-poor halo field stars and globular cluster stars play a crucial role both in guiding theoretical models of nucleosynthesis and in providing constraints upon the early star formation and concomitant nucleosynthesis history of our Galaxy. The abundance patterns characterizing the oldest and most metal deficient stars ([Fe/H] ≤ −3) are entirely consistent with their being products of metal-poor massive stars of lifetimes τ ≤ 108years. This includes both the elevated abundances of thealpha-elements (O, Mg, Si, S, Ca, and Ti) relative to iron-peak elements and the dominance of r-process elements over s-process elements. The nucleosynthetic contributions of lower mass AGB stars of longer lifetimes (τ ≈ 109years) begin to appear at metallicities [Fe/H] ≈ −2.5, while clear evidence for iron-peak nuclei produced in supernovae Ia (τ ≥ 1-2x109years?) does not appear until metallicities approaching [Fe/H] ~ −1. Similar trends are also suggested by abundances determined for gas clouds at high redshifts. We review the manner in which a knowledge of the abundances of the stellar and gas components of early populations, as a function of [Fe/H], time, and/or redshift, can be used to set constraints on their star formation and nucleosynthesis histories.

scholarly journals Did a gamma-ray burst initiate the late Ordovician mass extinction?

2004 ◽  
Vol 3 (1) ◽  
pp. 55-61 ◽  
Author(s):  
A.L. Melott ◽  
B.S. Lieberman ◽  
C.M. Laird ◽  
L.D. Martin ◽  
M.V. Medvedev ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Gamma Ray ◽  
Late Ordovician ◽  
Mass Extinctions ◽  
Solar Ultraviolet Radiation ◽  
Observable Universe ◽  
The Earth ◽  
Global Cooling ◽  
History Of ◽  
Solar Ultraviolet

Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth has experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRBs may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. A special feature of GRBs in terms of terrestrial effects is a nearly impulsive energy input of the order of 10 s. Due to expected severe depletion of the ozone layer, intense solar ultraviolet radiation would result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition, a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identified as the probable cause of this mass extinction, may have resulted from a GRB.

scholarly journals The most important message in the history of mankind

2016 ◽  
Vol 4 (2) ◽  
pp. 26-33
Author(s):  
Piotr Skubała
Keyword(s):  
Human Activities ◽  
Natural Capital ◽  
Biodiversity Loss ◽  
Negative Influence ◽  
Mass Extinctions ◽  
The Earth ◽  
Important Message ◽  
Sixth Mass Extinction ◽  
History Of ◽  
The Impact

AbstractIt the long history of life on the Earth five major mass extinctions were observed. Nowadays, the impact of human activities on the planet has accelerated the loss of species and ecosystems to a level comparable to a sixth mass extinction, the first driven by a living species. Surprisingly, this fact rarely reaches the public consciousness. The negative influence of human activity is observed in whole area of land ecosystems, whereas marine ecosystems are at risk of entering a phase of extinction unprecedented in human history. We have domesticated landscapes and ecosystems causing unforeseen changes in ecosystem attributes. Humanity has already overshot global biocapacity by 50% and now lives unsustainabily by depleting stocks of natural capital. Three the Earth-system processes - climate change, rate of biodiversity loss and interference with the nitrogen cycle - have already transgressed their boundaries. Human activities are of sufficient magnitude to suggest that we have triggered a new geological epoch, the Anthropocene. The “Biosphere 2” project revailed that we are not able to build and control a different system life and that we are totally dependent on the present biosphere. The experiment known in the literature as “The Tragedy of the Commons” reminds us that we need frugality and cooperation to solve environmental problems and survive.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z>30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

George Hoggart Toulmin: politics and geology

1978 ◽  
Vol 8 (4) ◽  
pp. 481-481
Author(s):  
ROY PORTER
Keyword(s):  
French Revolution ◽  
Social Order ◽  
Lower Class ◽  
Great Distance ◽  
The Earth ◽  
Christian View ◽  
The Social ◽  
French Enlightenment ◽  
Political Conservatism ◽  
History Of

The physician George Hoggart Toulmin (1754–1817) propounded his theory of the Earth in a number of works beginning with The antiquity and duration of the world (1780) and ending with his The eternity of the universe (1789). It bore many resemblances to James Hutton's "Theory of the Earth" (1788) in stressing the uniformity of Nature, the gradual destruction and recreation of the continents and the unfathomable age of the Earth. In Toulmin's view, the progress of the proper theory of the Earth and of political advancement were inseparable from each other. For he analysed the commonly accepted geological ideas of his day (which postulated that the Earth had been created at no great distance of time by God; that God had intervened in Earth history on occasions like the Deluge to punish man; and that all Nature had been fabricated by God to serve man) and argued they were symptomatic of a society trapped in ignorance and superstition, and held down by priestcraft and political tyranny. In this respect he shared the outlook of the more radical figures of the French Enlightenment such as Helvétius and the Baron d'Holbach. He believed that the advance of freedom and knowledge would bring about improved understanding of the history and nature of the Earth, as a consequence of which Man would better understand the terms of his own existence, and learn to live in peace, harmony and civilization. Yet Toulmin's hopes were tempered by his naturalistic view of the history of the Earth and of Man. For Time destroyed everything — continents and civilizations. The fundamental law of things was cyclicality not progress. This latent political conservatism and pessimism became explicit in Toulmin's volume of verse, Illustration of affection, published posthumously in 1819. In those poems he signalled his disapproval of the French Revolution and of Napoleonic imperialism. He now argued that all was for the best in the social order, and he abandoned his own earlier atheistic religious radicalism, now subscribing to a more Christian view of God. Toulmin's earlier geological views had run into considerable opposition from orthodox religious elements. They were largely ignored by the geological community in late eighteenth and early nineteenth century Britain, but were revived and reprinted by lower class radicals such as Richard Carlile. This paper is to be published in the American journal, The Journal for the History of Ideas in 1978 (in press).

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