Beryllium Abundances Research Articles

Nucleosynthesis during the Early History of the Solar System

Abundances in terrestrial and meteoritic matter indicate that the synthesis of D^2, Li^6, Li^7, Be^9, B^(10) and B^(11) and possibly C^(13) and N^(15) occurred during an intermediate stage in the early history of the solar system. In this intermediate stage, the planetary material had become largely separated, but not completely, from the hydrogen which was the main constituent of primitive solar material. Appropriate physical conditions were satisfied by solid planetesimals of dimensions from 1 to 50 metres consisting of silicates and oxides of the metals embedded in an icy matrix. The synthesis occurred through spallation and neutron reactions simultaneously induced in the outer layers of the planetesimals by the bombardment of high energy charged particles, mostly protons, accelerated in magnetic flares at the surface of the condensing Sun. The total particle energy was approximately 10^(45) ergs while the average energy was close to 500 MeV per nucleon. Recent studies of the abundance of lithium in young T Tauri stars serve as the primary astronomical evidence for this point of view. The observed abundances of lithium and beryllium in the surface of the Sun are discussed in terms of the astronomical and nuclear considerations brought forward. The isotope ratios D^2/H^1 = 1.5 × 10^(−4), Li^6/L^i7 = 0.08, and B^(10)/B^(11) = 0.23 are the basic data leading to the requirement that 10 per cent of terrestrial-meteoritic material was irradiated with a thermal neutron flux of 10^7 n/cm^2 s for an interval of 10^7 years. The importance of the (n, α) reactions on Li^6 and B^(10) is indicated by the relatively low abundances of these two nuclei. It is shown that the neutron flux was sufficient to produce the radioactive Pd^(107) and I^(129) necessary to account for the radiogenic Ag^(107) and Xe^(129) anomalies recently observed in meteorites. The short time interval, ∼ 6 × 10^7 years, required for the radioactive decays to be effective applies to the interval between the end of nucleosynthesis in the solar system and the termination of fractionation processes in the parent bodies of the meteorites. It is not necessary to postulate a short time interval between the last event of galactic nucleosynthesis and the formation of large, solid bodies in the solar nebula.

Nucleosynthesis during the Early History of the Solar System.

view Abstract Citations (6) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nucleosynthesis during the Early History of the Solar System. Fowler, William A. ; Greenstein, Jesse L. ; Hoyle, Fred Abstract Abundances in terrestrial and meteoritic matter indicate that the synthesis of D2, Li6, Li7, Be9, B10, and B11, and probably C'3 and N15 occurred during an intermediate stage in the early history of the solar system. In this intermediate stage, the planetary material had become largely separated from the hydrogen which was the main constitu nt of primitive solar material. Appropriate physical conditions were satisfied by solid planetesimals with dimensions from 1 to 50 m consisting of silicates and oxides of the metals embedded in an icy matrix. The synthesis occurred through spallation and neutron reactions simultaneously induced in the outer layers of the planetesimals by the bombardment of high-energy charged particles accelerated in magnetic flares at the surface of the condensing sun. Recent studies of the abundance of lithium in young, T Tauri stars serve as the primary astronomical evidence for this point of view. The observed abundances of lithium and beryllium in the surface of the sun are discussed. The isotope ratios D2H1=1.5X10-4, Li6$Li7=0.08, and B10/B11 =0.23 are the basic data leading to the requirement that 10% of terrestrial-meteoritic material was irradiated with a thermal neutron flux of 10 n;cm2- sec for an interval of 10' sec. The importance of the (n, ) reactions on Li6 and B'0 is indicated by the relatively low abundances of these two nuclei. It is shown that the neutron flux was sufficient to produce the radioactive Pd'07 and 1129 necessary to account for the radiogenic Ag'07 and Xe129 anomalies recently observed in meteorites. It is not necessary to postulate a short time interval between the last event of galactic nucleosynthesis and the formation of large, solid bodies in the solar nebula. Publication: The Astronomical Journal Pub Date: September 1961 DOI: 10.1086/108416 Bibcode: 1961AJ.....66..284F full text sources ADS |

The Abundance of Beryllium in Four Stars of Type a.

By means of a curve-of-growth analysis of high-dispersion spectrograms, the ratio of the abundance of Be to that of Fe was determined for alpha /sup 2/ CVn (AOp) and alpha CMa (Al V) relative to the ratio in alpha Lyr (AO V). In addition, the position of alpha Gem A (A1 V) on the abandance scale so defined was estimated. The absolute ratio of Be to H was obtained for alpha Lyr with the aid of a published model atmosphere. The results show that the abundance of Be in alpha Lyr is approximately one-fourth of the solar abundance (Be/H = 10/ sup -10/). the Be-to-Fe ratio in alpha CMa is atleast 40 times less than in alpha Lyr, and in alpha /sup 2/ CVn it is 25 times more. The abundance ratio in alpha Gem A appears to be similar to that in alpha Lyr. The absence of Be in alpha CMa is interpreted as a possible consequence of the transfer of matter from its white dwarf companion when the latter was an M supergiant. Ths Be abundance difference between alpha /sup 2/ CVn and alpha Lyr, together with the apparent absence of mechanisms to reduce the initial surface abundancemore » in alpha Lyr more than in alpha /sup 2/ CVn. suggest the active production of Be on the surface of alpha /sup 2/ CVn, probably in the early phases of its evolution. This suggestion, taken together with the evidence available on the abundance of lithium, indicates that the origin of Li, Be, and B is probably in nuclear processes at the surfaces of newly formed stars. (auth)« less

Abundance of Beryllium in the Earth's Crust.

Abundance of Beryllium in the Earth's Crust.

On the Abundance of Interstellar Beryllium.

view Abstract Citations (24) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Abundance of Interstellar Beryllium. Spitzer, Lyman, Jr. ; Field, George B. Abstract A search for the ultraviolet Be ii lines on high-dispersion spectra of 2 Ori and Per yields negative results. The resultant upper limits on N(Be ii), the number of Be ii ions in the line of sight, combined with the values of N (Na I), found from the ultraviolet Na doublet, yield an upper limit of about 2 x 10- for N(Be ii) /N (Na i). To find the over-all Be/Na ratio, this upper limit must be decreased by the ratio N(Na i)/N(Na ri), whose value will depend on whether the absorbing cloud is an H I or an H ii region. The assumption that the ratio of gas to dust is the same in these clouds as in the Galaxy at large makes it possible to compute the number of H atoms in the line of sight from the observed color excess. This computed number is an order of magnitude too great for an H ii region, in view of the absence of any interstellar Balmer emission from the neighborhood of these stars. Analysis of conditions in an H I region shows that N(Na i)/N(Na ii) is probably about 2 X 10 , and the ratio N(Be)/N(Na) becomes less than about 4 X 10- . This low value is about an order of magnitude less than the mean of the values found in the sun or in meteorites. The ratio ]\T(Ca) /N(Na) is also believed to be less in the interstellar gas than in the sun and in meteorites by a factor of about 40. Possibly both Ca and Be atoms, to a greater extent than Na atoms, may be locked up in grains. Publication: The Astrophysical Journal Pub Date: March 1955 DOI: 10.1086/145988 Bibcode: 1955ApJ...121..300S full text sources ADS | data products SIMBAD (2)

Abundance of Lithium, Beryllium, and Boron in the Primary Cosmic Radiation

The flux of nuclei of charge greater than two of the primary cosmic radiation has been measured at 41\ifmmode^\circ\else\textdegree\fi{} and 55\ifmmode^\circ\else\textdegree\fi{} geomagnetic latitudes with photographic emulsions flown in Sky Hook balloons. The technique used at the lower latitude is similar in principle to that employed originally by Bradt and Peters, while that used at the higher latitude is the method of Dainton, Fowler, and Kent. The different experimental methods are discussed and the latter is found more satisfactory for the light-element problem. Primary flux values are reported for the medium nuclei ($6l~Zl~10$) and the heavy nuclei ($Zg10$) at the two latitudes. It is concluded that there exists a finite primary flux of the light nuclei ($3l~Zl~5$) and the most reliable value from these experiments of the ratio of the primary light-nuclei flux ${{N}_{L}}^{0}$ to the primary medium-nuclei flux ${{N}_{M}}^{0}$ at the top of the atmosphere is found to be 0.46\ifmmode\pm\else\textpm\fi{}0.15.

The Abundance of Beryllium in the Sun.

The Abundance of Beryllium in the Sun.

LXXI. The abundance of lithium, beryllium, and boron in the primary cosmic radiation

Summary In a previous paper, a method of determining the charge, of heavy nuclei in the cosmic radiation was described which depended on measuring the δ-ray density along a track in a photographic emulsion and the multiple scattering of the particle. The results suggested the presence of a large proportion of the light elements lithium, beryllium and boron in the radiation, a result in contradiction with that of other workers. The first part of the present paper describes a re-examination of the original method and evidence for its reliability. It is shown that an alternative method, based on observations of grain-density in the tracks of heavy particles recorded in less sensitive emulsions, gives results in agreement with those obtained by the δ-ray method. In the second part, the results of a more extended series of measurements by the, δ-ray method are described. The results indicate that at geo-magnetic latitude 55° N., the flux of lithium, beryllium and boron nuclei in the cosmic radiation is equal t...

Abundance of Lithium, Beryllium, Boron, and Other Light Nuclei in the Primary Cosmic Radiation and the Problem of Cosmic-Ray Origin

A combination of sensitive and insensitive photographic emulsions is used to improve the accuracy of measurement of the specific energy loss of relativistic nuclei. In recent years, various new theories of the origin of cosmic rays have been proposed. These proposed theories are classified according to the proposed mechanism for acceleration of the nuclei of the primary cosmic radiation or according to the assumptions made concerning the source region. The most abundant elements in the known universe are hydrogen, helium, carbon, oxygen, nitrogen, magnesium, and silicon. This chapter focuses on the production of lithium, beryllium, and boron fragments in energetic collisions between nuclei. The nuclear fragments of an average star produced by a singly charged particle in the light nuclei of the emulsion must carry 7.95 units of charge, assuming a contribution from carbon, nitrogen, and oxygen nuclei proportional to their geometric cross-sections. The absence or scarcity of lithium, beryllium, and boron nuclei in the primary radiation indicates that as far as the distribution between light and heavy elements is concerned, the chemical composition at the source is similar to the average chemical composition of the universe.