Solar helium

This value is much lower than the energy released in carbon cycle or solar helium-hydrogen cycle. 

C. Runge and Paschen found, however, that the spectrum of the gas from cleveite gave a yellow line which was double. Not until the Ds line of solar helium had also been conclusively proved to be double, did Runge and Paschen admit the existence of helium in cleveite (69, 72). 

The compositions to be considered are hydrogen-rich, or, speaking loosely, solar helium-rich, or, loosely, Wolf-Rayet deflagration - initially a mixture of heavy elements from carbon to radioactive nickel, which decays through cobalt to iron and detonation - initially a mixture of just helium and radioactive nickel. 

Honda, M., Reynolds, J. H., Roedder, E., Epstein, E. (1987) Noble gases in diamonds Occurrence of solar helium and neon. J. Geophys. Res., 92, 12507-21. 

Nichols, R. H., Jr., Hohenberg, C. M., Olinger, C. T. (1994) Implanted solar helium, neon, and argon in individual lunar ilmenite grains Surface effects and temporal variation in the solar wind composition. Geochim. Cosmochim. Acta, 58, 1031-42. 

The second consequence is that it would have been relatively easy to dissolve a small amount of this solar gas at high pressure into the basaltic melts at the Earth s surface (Mizuno et al., 1980). This ingassing provides a mechanism for transporting nebular gases into the Earth s interior. The ultimate source of solar helium and neon in the mantle is unknown. At one time, it was thought to be the mantle (Allegre et al., 1983) and this still seems most likely (Porcelli and Ballentine, 2002) but the core also has been explored (Porcelli and Halliday, 2001) as a possible alternative. 

In the solid Earth, production of nucleogenic Ne is coupled to that of radiogenic " He. This is because production of Ne is directly proportional to the a-particle production ratio from the uranium and thorium series. The Ne/ He production ratio is constant and has been estimated at a value of 4.5 X 10 (Yatsevich and Honda, 1997). In this way, if the Earth accreted with solar helium and neon and initial ratios were modified by production of Ne and " He in a fixed proportion then the present-day He/ He and Ne/ Ne ratios in the mantle should be correlated. Honda et al. (1993) noted a strong correlation between OIB helium and neon isotopes such that steeper trajectories in three-isotope neon space were characterized by samples with high He/ He ratios. Indeed, they showed that it was possible to estimate the He/ He ratio of a suite of OIBs based solely on measurements of the neon isotope composition. 

The core has also been considered as a source of noble gases. During formation of the Earth, the core may have incorporated sufficient quantities of solar helium to now supply ocean islands with high He/" He ratios (Porcelli and HaUiday, 2001). In this case, such ratios trace the interaction between the core and mantle (see Chapter 2.06). However, the core cannot be used to explain the radiogenic isotope budgets (see Section 4.11.3) nor the heat- He budget, and so must be coupled with a mantle model for these features. 

A problem with adopting the solar wind He/" He ratio as representative of the solar nebula is the production of He from deuterium very early in solar system history consequently, the solar wind value (—4.4 X 10 " ) is too high by a factor between —2.5 and —3 relative to the proto-Sun (Geiss and Reeves, 1972). To circumvent this difficulty, recourse has been made to analyzing the giant planets whose atmospheres are expected to reflect proto-solar values (Wieler, 2002). Jupiter is the only giant planet whose atmospheric He/" He ratio has been determined (Mahaffy et al, 1998). Its value of 1.66 Xl0 (—120Ra where Ra = air He/" He)—remarkably similar to measurements on primitive meteorites (see below), is now adopted as most representative of primordial (proto-solar) helium. 

Hiyagon H (1994) Retention of solar helium and neon in IDPs in deep sea sediments. Science 263 1257-1259... 

Not quite sure of his results, Ramsay sent an ampoule with the gas to W. Crookes. A day later a telegram was received from Crookes which read Krypton is helium, 587.49 come and see. The figure 587.49 corresponded to the wavelength of the solar helium on a specially calibrated scale. Although these data facilitated the identification of helium on the earth, otherwise this discovery was independent. 

Timothy, A.F., Timothy, J.G. Long term variations in the solar helium II Ly-alpha line. J. Geophys. Res. 75, 6950 (1970)... 

Gr. helios, the sun). Janssen obtained the first evidence of helium during the solar eclipse of 1868 when he detected a new line in the solar spectrum. Lockyer and Frankland suggested the name helium for the new element. In 1895 Ramsay discovered helium in the uranium mineral clevite while it was independently discovered in cleveite by the Swedish chemists Cleve and Langlet at about the same time. Rutherford and Royds in 1907 demonstrated that alpha particles are helium nuclei. 

Extraterrestrial dust particles can be proven to be nonterrestrial by a variety of methods, depending on the particle si2e. Unmelted particles have high helium. He, contents resulting from solar wind implantation. In 10-)J.m particles the concentration approaches l/(cm g) at STP and the He He ratio is close to the solar value. Unmelted particles also often contain preserved tracks of solar cosmic rays that are seen in the electron microscope as randomly oriented linear dislocations in crystals. Eor larger particles other cosmic ray irradiation products such as Mn, Al, and Be can be detected. Most IDPs can be confidently distinguished from terrestrial materials by composition. Typical particles have elemental compositions that match solar abundances for most elements. TypicaUy these have chondritic compositions, and in descending order of abundance are composed of O, Mg, Si, Ee, C, S, Al, Ca, Ni, Na, Cr, Mn, and Ti. 

As evidence that this is so, consider that the element helium was detected in the sun before it was found on earth Though oxygen contains 0.2% of the oxygen-18 isotope on earth, it, too, was first detected in a solar spectrum. Two... 

The eventual resolution of the issue was that argon was fitted into a new group within the table, between the halogens and the alkali metals. In the meantime, the properties were being investigated of a gas first detected in 1868 by Frankland and Lockyer by spectroscopic analysis of solar radiation. Shortly after the argon episode, it was discovered that this gas, appropriately named helium , could be... 

Amorphous Silicon. Amorphous silicon is generally deposited by Reaction (4) at a deposition temperature of 560°C and at low pressure (ca. 1 Torr).P l Helium RF plasma CVD is also commonly used, especially in the production of solar photovoltaic devices. 

As can be seen in Fig. 2-1 (abundance of elements), hydrogen and oxygen (along with carbon, magnesium, silicon, sulfur, and iron) are particularly abundant in the solar system, probably because the common isotopic forms of the latter six elements have nuclear masses that are multiples of the helium (He) nucleus. Oxygen is present in the Earth s crust in an abundance that exceeds the amount required to form oxides of silicon, sulfur, and iron in the crust the excess oxygen occurs mostly as the volatiles CO2 and H2O. The CO2 now resides primarily in carbonate rocks whereas the H2O is almost all in the oceans. 

Astronomers use spectroscopy to identify the composition of the sun and other stars. A striking example is the discovery of the element helium. In 1868, astrono-mers viewing a solar eclipse observed emission lines that did not match any known element. The English astronomer Joseph Lockyer attributed these lines to a new element that he named helium, from hellos, the Greek word for the sun. For 25 years the only evidence for the existence of helium was these solar spectral lines. 

In 1894, the Scottish chemist William Ramsay removed nitrogen and oxygen from air through chemical reactions. From the residue, Ramsay Isolated argon, the first noble gas to be discovered. A year after discovering argon, Ramsay obtained an unreactive gas from uranium-containing mineral samples. The gas exhibited the same spectral lines that had been observed in the solar eclipse of 1868. After helium was shown to exist on Earth, this new element was studied and characterized. 

According to present-day concepts, our solar system was formed from a huge gas-dust cloud several light years across in a side arm of the Milky Way. The particle density of this interstellar material was very low, perhaps 108-1010 particles or molecules per cubic metre, i.e., it formed a vacuum so extreme that it can still not be achieved in the laboratory. The material consisted mainly of hydrogen and helium with traces of other elements. The temperature of the system has been estimated as 15 K. 

Only the lightest gases, such as hydrogen and helium, could easily escape the gravitational field of the Earth. In contrast to earlier assumptions, it is now believed that the young Earth probably had either no atmosphere at all or only a very thin one, since the proportion of the primeval solar nebula from which the terrestrial planets were formed consisted mainly of non-volatile substances. 

The planet Jupiter occupies a special position in the solar system. It is the largest and heaviest planet, with a mass of 1/1,047 that of the sun. Jupiter consists almost solely of hydrogen and helium with a ratio similar to that found in the sun itself He H 1 10. Small amounts of some heavier elements are present, such as B, N, P, S, C and Ge. The density of Jupiter has been calculated as 1,300 kg/m3. Its atmosphere can be divided into three zones (starting from the outermost) ... 

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