Heavy Elements And Age Determinations
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Peculiaritiesof -elementAbundancesinGalactic Open Clusters
elements (oxygen and magnesium) exhibit diﬀerent dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits in clusters with high, elongated orbits satisfying the criterion (Z2 max + 4e2)1/2 > 0.40 and in ﬁeld stars of the Galactic thin disk (Z max is the
Assessment of Heavy Metals Concentration in Some Selected
The toxicity of heavy metals depends upon the chemical form of elements. Heavy metals are dangerous in the form of their cations and are highly toxic when bonded to the short chains of carbon atoms (Kirmani et al., 2011). Plants may absorb heavy metals from soil, water or air. Medicinal herbs may
Heavy element abundances in the second parameter globular
NGC 288 and 8 stars in NGC 362. The abundances of 15 heavy elements are re-ported for the two clusters, including the s-process elements Y, Zr, Ba, La and Ce and r-process element Eu. The abundances were derived using two separate and in-dependent techniques: The Spectroscopic Approach, where the atmospheric models
Element Abundances through the Cosmic Ages
ﬁrst time, to detect and measure a wide range of chemical elements directly in stars, H II regions, cool interstellar gas and hot intergalactic medium, all observed when the universe was only ∼ 1/15 of its present age. Our simple-minded hope is that, by moving back to a time when the universe was young, clues to the nature, location, and
Atomic di usion in old stars helium, lithium and heavy elements
Atomic di usion in old stars 3 6500 6000 5500 5000 5.4 5.6 5.8 6.0 6.2 log N X / N H +12 Mg 6500 6000 5500 5000 4.2 4.4 4.6 4.8 5.0 Ca 6500 6000 5500 5000 effective temperature T eff
Introduction Radioactivity and the systematics of its use as
age. The assumption of a constant atmospheric 14C/12C Absolute Age Determinations: Radiometric, Table 1 Radioactive elements commonly used for absolute age determinations Parent isotope Production mechanism Daughter isotope Half-Life (Million years) 7-Berylium (7Be) Cosmogenic 7-Lithium ( Li) 53 days
The temporal evolution of the neutron-capture elements in the
The production of light and heavy s-process elements 1-5 Gyr: [Ba/Y] increases as time goes on. Low-mass AGB stars of solar and sub-solar metallicity yield more Ba than Y. 5-6 Gyr: inversion of the trend? 6-8 Gyr: bunch of old thin disk stars with high [Ba/Y] ratios. The production of heavy s-process elements is more favourable at
PRMTIA PRDCTS ASSCIATI ITRATIA - PPAI
age grade or age label on the product or packaging. 2. Whether the product is represented in its packaging, display, promotion or advertising as appropriate for use by children12 years of age or younger. 3. Whether the product is commonly recognized by consumers as being intended for use by a child 12 years of age or younger. 4.
The synthesis of the light elements is sensitive to physical conditions in the early radiation-dominated era at a temperature T ∼ 1 MeV, corresponding to an age t ∼ 1 s. At higher temperatures, weak interactions were in thermal equilibrium, thus ﬁxing the ratio of the neutron and proton number densities to be n/p = e−Q/T, where Q = 1
How Old is Earth, and How Do We Know?
carbon, uranium, potassium, and other elements, provides accurate age estimates for events back to the formation of Earth more than 4.5 billion years ago. These and other dating techniques are mutually consistent and underscore the reality of deep time in Earth history. Keywords Geochronology.Dendrochronology.Varves.
CHAPTER 16: LABOR STANDARDS
Federal wage determinations are generally issued for four categories: Building, Residential, Heavy, and Highway. It is important to understand the differences when determining which rate category to request to avoid paying wages from an inappropriate determination. Building construction generally includes construction of sheltered enclosures with
1 The Universe we see - University of Washington
seconds in a year). Other age determinations exist: 1. From dating the earth s crust using radioactive decay, one nds it to be at least 3:7 109 years old. 2. Dating the age of heavy elements, one nds that they were created (perhaps in a super-nova) between 8 109 and 15 109 years ago. 3. One can also estimate the ages of globular clusters.
S Age Estimates of Globular Clusters in the Milky Way
heavy elements such as iron in stars within such clusters. This abundance can be less than one-hundredth of that measured in the Sun, which suggests that the gas from which these objects coalesced had not previously experienced significant star formation and evolution. Thus, an accurate determination of the age of the oldest clusters can yield
The formation of the heaviest elements
such determinations may be plagued by large systematic un-certainties, but at face value, the derived stellar age suggests that the r-process must have been operating when the universe was chemically quite primitive. In CS 22892-052 and other so-called r-II stars, the abundance of r-process elements such as europium relative to that of iron
DIVISION OF GEOLOGICAL AND GEOPHYSICAL SURVEYS
sity of Alaska Geophysical ~nstitute) provided K-Ar age determinations from intrusive rocks (table 4). The Division of Geological and Geophysical Surveys Geochemical Laboratory analyzed rock, stream-sediment , and pan-concentrate samples (tables 5-8). Gold production figures from Ophir precinct and Candle
Scientist refines cosmic clock to determine age of Milky Way
Age determinations are crucial to a fundamental decay of two long-lived radioactive elements, uranium-238 and thorium-232. According to and other heavy elements that play an important
stratigraphic - Alaska
1981) and uranium lead age determinations (Aleini koff and others, in press), chemical analysis of mineralized and background rocks, chemical analysis of the minus-80-mesh fraction of stream sediment samples (Tripp and Crim, 1983), chemical analysis of and identification of selected minerals in nonmagnetic,
Population Synthesis in the Blue II. The Spectroscopic Age of
Vazdekis et al. (2001) greatly improved over previous spectroscopic age determinations, which gave ages in excess of 20 Gyrs (Gibson et al. 1999). In particular, they showed that -enhancenment and di usion of heavy elements cause a reduction in both the CMD and spectroscopic ages of 47 Tuc by several Gyrs.
letters to nature Measurementofstellarage fromuranium decay
CS31082-0018, a star which is strongly overabundant in its heavy elements. The derived uranium abundance, log(U/H) = -13.7 6 0.14 6 0.12 yields an age of 12.5 6 3 Gyr, though this is still model dependent. The observation of this cosmochronometer gives the most direct age determination of the Galaxy. Also, with improved
Volume 245 ASTROPHYSICAL AGES AND TIME SCALES
Eddington: A European Space Mission That Will Measure the Age of the Stars 304 A. Gimenez, F. Favata The Light Elements in TO and SGB Stars of Two Globular Clusters: Implications for Photometric Age Determinations 307 VLT Globular Cluster Team: R. G. Gratton, P. Bonifacio, A. Bragaglia, E. Carretta, V. Castellani, M. Centurion,
The Milky Way Galaxy
The first description of the formation of the Galaxy was published by the German philosopher Immanuel Kant (1724-1804) in his 1755 book, the Allgemeine Natur-
UNITED STATES CONSUMER PRODUCT SAFETY COMMISSION 4330 EAST
contain heavy elements that would exceed the limits specified in the Commission s toy standard, ASTM F963-11. Based on this determination, unfinished and untreated wood in toys does not require third party testing for the heavy element limits in ASTM F963.
UNITED STATES CONSUMER PRODUCT SAFETY COMMISSION 4330 EAST
The third party testing burden could only be reduced if all heavy elements listed in section 4.3.5 have concentrations below their solubility limits. Because third party conformity assessment bodies typically run one test for all of the ASTM heavy elements, no testing burden reduction would be achieved if any one of the heavy elements requires
1, 1 - MDPI
Feb 06, 2020 used for age dating and provenance identiﬁcation of geologic materials (e.g., ). Strontium has four stable isotopes (84, 86, 87, and 88) with 87Sr being produced from the radioactive decay of 87Rb. Accurate Rb-Sr age determinations are only obtained in a closed system. Age-corrected initial 87Sr/86Sr
HD 140283: A STAR IN THE SOLAR NEIGHBORHOOD THAT FORMED
or not GC ages are compatible with the age of the Universe. In addition to the issue of distances, age determinations of stars in GCs require knowledge of interstellar extinction and chemical compositions, including the abundances of individual heavy elements. An alternative approach to stellar chronology is to determine
The age of the universe from nuclear chronometers
mately uniform nucleosynthesis rate yields an age for the Galaxy of 12.8 6 3 Gyr, which again is consistent with current determinations from other methods. Estimates of the age of the Galaxy, and thereby limits on the age of the Universe, can be obtained by three independent means: (i) the age of the elements by radioactive dating
Simultaneous determinations of U Pb age, Hf isotopes and
daughter element hafnium, and rare earth elements (REE), especially heavy rare earth elements (HREE), coupled with an extremely low Lu/Hf ratio and negligible incorporation of the daughter element lead and parent element lutetium during crystallization. In addition, two geochronometers (235U 207Pb and 238U 206Pb) can be used to test the
s-Processing in the Galactic Disk. I. Super-Solar Abundances
We present here further abundance determinations, relative to four other elements hav-ingimportant s-processcontributions,with theaim of investigatingwhetherthegrowth found for [Ba/Fe] is or not indicative of a general property, shared also by the other heavy elements formed by slowneutron captures. In particular, we derivedabundances
The Age of the Earth - New Mexico State University
Physical Determinations of Earth s Age Sedimentation Rates Thickness/Rate = 150 km/0.3 mm per year = 500 Myr (Values from 3 Myr to 1.5 Gyr) Salinity of the Seas John Joly, 1899: 90 - 100 Myr Cooling Times Comte de Buffon,1779: 75,000 yr (by experiment) Lord Kelvin, 1862: 98 Myr; 20 to 400 Myr Age of the Sun Hermann von Helmholtz,1854: 21 Myr
arXiv:astro-ph/0605137 v1 4 May 2006
nature of heavy element nucleosynthesis. In addition age determinations, based upon long-lived radioactive nuclei abundances, can now be obtained. These stel-lar abundance determinations depend critically upon atomic data. Improved laboratory transition probabilities have been recently obtained for a number of elements.
Lecture 11 The radioactive Earth
Heavy materials sink to the bottom due to gravitation, sedimentation, and centrifugation and form Fe-Ni core, a chemical incompatible layer of actinide elements forms around it! The earth radius is 6370 km, the surface area is
DATING THE PAST WITH RADIOACTIVITY
age determinations of samples aged 100 000 to more than one million years (Thurber). At the other end of the scale, it was shown that the use of lead-210, formed in the atmosphere through the decay of the short-lived gas radon-222, is useful for dating geo-chemical processes which have taken place within the last hundred years or so.
for the same heavy element fraction Z, but with the a-elements being enhanced relative to the iron within the metal group. In particular, oxygen is enhanced by [O/ Fe] 0.5, and the other a-elements by similar, but slightly varying, amounts, according to the observed values in low-metallicity stars (see, e.g., Sneden, & TruranWheeler, 1989).
The solar neighbourhood age-metallicity relation - Does it
comes more and more enriched in heavy elements. Thus we may expect the more recently formed stars to have a higher metallicity than those formed at an earlier epoch. By obtaining ages as well as metallicities for a represen-tative stellar sample we should therefore be able to derive an age-metallicity relation. Such a relation would provide
Astronomy c ESO 2009 Astrophysics - Uppsala University
elements such as osmium (if available) seem better partners for age determinations, as theoretical predictions of their cor-responding r-process yields are more robust than those for pairs of heavy and intermediate mass elements. However, the dom-inant transitions of third-peak elements, which are detected as neutral species, lie in the UV.
Nutritional Metals in Foods by AAS
heavy metals. 3.3 RDI of minerals according to age and gender The Recommended Daily Intake, RDI of metals is related directly to age, and gender. The requirements for babies toddle rs children , adolescents, and elderly vary with gender and country due to soil type. These requirements ar e continually being reviewed in the light of
STELLAR ABUNDANCE OBSERVATIONS AND HEAVY ELEMENT FORMATION
New observations of n-capture elements in low-metallicity Galactic halo stars providing clues and constraints on: 1. Synthesis mechanisms for heavy elements early in the history of the Galaxy 2. Identities of earliest stellar generations, the progenitors of the halo stars 3. Suggestions on sites, particularly site or sites for the r-process 4.
New N-Capture Element Abundance Determinations in an r
New Element Abundance Determinations John J. Cowan 1. Introduction Abundance determinations of the neutron-capture (aka heavy) elements in metal-poor halo stars are fundamentally important to our understanding of the early history of the Galaxy and the Universe. These elements are synthesized in either the slow (s) or rapid (r) neutron-capture
HELIOSEISMOLOGICAL IMPLICATIONS OF RECENT SOLAR ABUNDANCE
present surface ratio of heavy element to hydrogen mass frac-tions of Z=X ¼ 0:0229.Themodel BP04+,whichincorporates the new determinations of the solar heavy-element composi-tion, has a much lower ratio of heavy elements to hydrogen, Z=X ¼ 0:0176. Since new solar abundance determinations are being reported as they become available, Table 1 of
University of Texas Rio Grande Valley ScholarWorks @ UTRGV
age determinations may require very detailed knowledge of the chemical composition. It is well known (Tripicco & Bell 1995; Korn et al. 2005; Serven et al. 2005) that increasing the abundance of a particu-lar element can alter a syntheticspectrum by increasing or de-creasing the absorption features, or opacity, of various atomic