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MTM Series Trapezium Mill

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The helium content of globular clusters: light element ...

Abstract. Recent studies suggest that the helium content of multiple stellar populations in globular clusters (GCs) is not uniform. The range of helium varies

Primordial Helium, Created in Big Bang, Detected at Long ...

The assumed helium sedimentation model, on average, produces a negligible increase in the gas mass inferred within large radii (r < r500) (1.3 +/- 1.2 per cent) and a (10.2 +/- …

Terrestrial helium

INTRODUCTIONIsotopic measurements of helium in oceanic basalts (Lupton and Craig, 1975;Kurz et al, 1982;Allègre et aL, 1983) have shown that the mantle beneath the global mid-ocean ridge (MOR) system is characterized by a uniform composition. 3 He/ 4 He ratios display a narrow range, between 8 and 10 times the atmospheric value (R a ), and are three orders of …

Terrestrial helium

May 01, 1996· The measured helium concentrations in groundwater are lower than the calculated losed systemvalues; therefore, the water/rock system as a whole has lost helium since the time of sedimentation. 2) The total mineralisation and major element chemistry of the highly mineralised Permian groundwaters (Weiach) are quite different from those in the ...

Impact of thermal diffusion and other abundance anomalies ...

Helium is mostly once ionized but, as long as the e ective temperature of the ionizing stars is above 90,000 K, emission lines of HeII can also be detected. In particular, for Teff =100,000 K, the fraction of twice ionized He is 29% for a model atmosphere SED and 10% for a black body SED.

HELIUM SEDIMENTATION AND THE ULTRAVIOLET UPTURN IN ...

been2 x 10-15 cm3 cm-2year` over the past 40 million years [variation from 1 x 105to5 X 10-15cm3cm-2year-] (17). UsinganETflux of50Ggyear-1, basedon siderophiles (8) andanIDP3Heconcentra- tion of 4 x 10` cm3 g` (18), the total 3Hedelivered to the Earth is 2 x 106 cm3 year-1. Siderophiles, ofcourse, survive at- mospheric entry but some of the volatiles are …

Helium

The assumed helium sedimentation model, on average, produces a negligible increase in the gas mass inferred within large radii (r < r500) (1.3 +/- 1.2 per cent) and a (10.2 +/- …

Primordial Stellar Populations

Jun 13, 1995· This is the long-sought primordial helium, one of the two original chemical elements (the even more abundant hydrogen being the other) from which all stars and galaxies were being formed in that ...

Helium abundance in galaxy clusters and Sunyaev

Therefore in practice, the helium abundance is usually assumed to be equal to its primordial value. The latter is known quite accurately from the theory of big bang nucleosynthesis which predicts the He fraction in the total baryonic mass density of Y = 0.2482 ± 0.0007 (Walker et al. 1991 ; Kneller & Steigman 2004 ).

HELIUM SEDIMENTATION AND THE ULTRAVIOLET UPTURN …

stars in globular clusters have a common origin. An extremely high abundance of helium (Y ∼ 0.4) allows for a working hypothesis, but its origin is unclear. Peng & Nagai proposed that primordial helium sedimentation in dark halos over cosmic timescales may lead to extreme helium abundances in galaxy cluster centers. In this scenario,

The diffusion of helium through sedimentary rocks ...

Source of helium Two classes of helium can be envisaged: primordial helium, and radiogenic helium produced since the formation of the earth. In view of the wide cosmic abundance of helium it is clear that primordial helium did exist in the early stages of the earth's formation and a portion of this helium is still present. ... The sedimentation ...

Heating and ionization of the primordial intergalactic ...

Helium and temperature vertical profiles are well described by the classic diffusion‐advection equation. On the basis of He profiles, we estimate the advection rate on the rim of the pockmark between 1.2 and 2.3 mm/a. ... whereas most of the 3 He is primordial in origin. ... Knowledge of the sedimentation rate is a key point in order to model ...

Helium and argon isotopes in rocks, minerals, and related ...

Since decreasing the helium abundance to resolve the conflict would have required values well below the primordial one (in accordance to what we have obtained in Section 3.3 and 4), Lebreton et al. (1999) advocated two processes that could help in solving the discrepancy : i) diffusion of helium and heavier elements in stellar models and ii ...

Gravitational diffusion in the intra

We revisit the process of gravitational sedimentation of helium and heavy elements in the intracluster medium. We find that helium applies an inward drag force on heavy elements, boosting their sedimentation speed to nearly half its own. This speed is almost independent of the mass and the electric charge of heavy elements.

THE ULTRAVIOLET UPTURN IN ELLIPTICAL GALAXIES AND ...

May 01, 1996· The measured helium concentrations in groundwater are lower than the calculated losed systemvalues; therefore, the water/rock system as a whole has lost helium since the time of sedimentation. 2) The total mineralisation and major element chemistry of the highly mineralised Permian groundwaters (Weiach) are quite different from those in the ...

Elements of the past: Big Bang Nucleosynthesis and ...

INTRODUCTIONIsotopic measurements of helium in oceanic basalts (Lupton and Craig, 1975;Kurz et al, 1982;Allègre et aL, 1983) have shown that the mantle beneath the global mid-ocean ridge (MOR) system is characterized by a uniform composition. 3 He/ 4 He ratios display a narrow range, between 8 and 10 times the atmospheric value (R a ), and are three orders of …

(PDF) The helium abundance and ΔY/ΔZ in lower main ...

Aug 04, 2011· An extremely high abundance of helium (Y ~ 0.4) allows for a working hypothesis, but its origin is unclear. Peng & Nagai proposed that primordial helium sedimentation in dark halos over cosmic timescales may lead to extreme helium abundances in galaxy cluster centers.

Nondetection of Helium in the Upper Atmospheres of Three ...

Jan 05, 2021· Understanding how the Earth evolved from its accretion to the present-day conditions is a major quest of the Earth sciences. This contribution focuses on the evolution of the deepest realms of our planet sampled by basalts in ocean islands (such as Hawaii) during the last ∼100 to 150 million years and diamond-bearing kimberlites emplaced in continents since ∼2 …

Nondetection of Helium in the Upper Atmospheres of Three ...

The theory of nucleosynthesis during the first few minutes after the big bang makes very clear predictions about the abundances of light atomic nuclei in the early universe – about the contributions of hydrogen (single protons), deuterium, helium-3, helium-4, lithium-7 to the total mass of ordinary matter contained within a given region.

(PDF) 19. HELIUM AND SULFUR ISOTOPES OF SULFIDE MINERALS ...

Nov 11, 2020· The direct detection of helium in the atmosphere of a planet would be the smoking-gun evidence for the presence of a primary atmosphere accreted from the primordial nebula. This is because no other formation mechanism (e.g., sublimation of ices or outgassing of rocky material) can give rise to the presence of large quantities of helium in a ...

Helium

Nov 11, 2020· The direct detection of helium in the atmosphere of a planet would be the smoking-gun evidence for the presence of a primary atmosphere accreted from the primordial nebula. This is because no other formation mechanism (e.g., sublimation of ices or outgassing of rocky material) can give rise to the presence of large quantities of helium in a ...

Helium transport in sediment pore fluids of the Congo ...

primordial helium while the blue MS is highly helium-enhanced by Y = 0.08 ± 0.01. Fur-thermore, the red MS exhibits an intrinsic broadening that cannot be attributed to photometric errors only and is consistent with a spread in helium of ∼0.025 dex. The comparison between