The solar photospheric abundance of hafnium and thorium

Caffau, E.; Sbordone, L.; Ludwig, H.‐G.; Bonifacio, P.; Steffen, M.; Behara, N. T.

doi:10.1051/0004-6361:200809629

Cited by 31 publications

(45 citation statements)

References 27 publications

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“…We found similar results for Fe, Hf, and Th, where the abundances derived from disc-integrated spectra are lower by 0.02, 0.05, and 0.02 dex, respectively, than the disccentre abundances (see Caffau et al 2008 andCaffau et al 2010 for details). A similar behaviour is seen when using 1D model atmospheres.…”

Section: Investigation Of Zr II Linessupporting

confidence: 79%

The solar photospheric abundance of zirconium

et al. 2011

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Zirconium (Zr), together with strontium and yttrium, is an important element in the understanding of the Galactic nucleosynthesis. In fact, the triad Sr-Y-Zr constitutes the first peak of s-process elements. Despite its general relevance not many studies of the solar abundance of Zr were conducted. We derive the zirconium abundance in the solar photosphere with the same CO 5 BOLD hydrodynamical model of the solar atmosphere that we previously used to investigate the abundances of C-N-O. We review the zirconium lines available in the observed solar spectra and select a sample of lines to determine the zirconium abundance, considering lines of neutral and singly ionised zirconium. We apply different line profile fitting strategies for a reliable analysis of Zr lines that are blended by lines of other elements. The abundance obtained from lines of neutral zirconium is very uncertain because these lines are commonly blended and weak in the solar spectrum. However, we believe that some lines of ionised zirconium are reliable abundance indicators. Restricting the set to Zr II lines, from the CO 5 BOLD 3D model atmosphere we derive A(Zr) = 2.62 ± 0.06, where the quoted error is the RMS line-to-line scatter.

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Section: Investigation Of Zr II Linessupporting

confidence: 79%

The solar photospheric abundance of zirconium

et al. 2011

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“…Caffau et al 2008b report a nominal Th abundance A(Th) = 0.08±0.03, which should not be over-interpreted because of the line blends.…”

Section: Thoriummentioning

confidence: 88%

Solar System Abundances of the Elements

Lodders

2010

Astrophysics and Space Science Proceedings

279

176

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Summary. Representative abundances of the chemical elements for use as a solar abundance standard in astronomical and planetary studies are summarized. Updated abundance tables for solar system abundances based on meteorites and photospheric measurements are presented.Keywords: solar system abundances, solar photosphere, meteorites, CI chondrites Motivations to Study Solar System Elemental AbundancesThe investigations of what chemical elements exist in nature and in which quantities have a long history. The determination of elemental abundances in various celestial objects is still a very active field in astronomy, planetary science, and meteoritics. There are multiple motivations for studying the solar system abundances of the chemical elements. One reason to study this overall composition of the solar system is to understand how the diversity of planetary compositions, including that of our home planet, can be explained, since all planets in the solar system share a common origin from the material of the protosolar disk (the solar nebula).The composition of the sun determines how the sun works and evolves over time, as composition influences the interior structure of the sun. Although the Sun is mainly composed of H and He, other heavy elements such as C, N, O, Ne, Fe, etc., are important opacity sources that influence the energy transport out of the sun through radiation and convection. The sun is a typical main sequence dwarf star and its composition is a useful baseline for comparison to abundances in other dwarf stars and to changes that appear in advanced stages of stellar evolution. For example, relative to the sun's composition, red giant stars show observable abundance variations that are the result of nucleosynthesis operating in giant stars, and these products have been dredged up from stellar interiors to the stellar exteriors. 3The solar system abundances are a useful local galactic abundance standard because many nearby dwarf stars are similar in composition; however, in detail there are some stochastic abundance variations (e.g., Edvardsson et al. 1993, Nordstrom et al. 2004, Reddy et al. 2003, 2006. The term "cosmic" abundances should be avoided because abundances generally decrease with galactocentric distance. There are also abundance differences between our galaxy and galaxies at high red-shift; hence there is no generic "cosmic" composition that applies to all cosmic systems.Finally, solar abundances are a critical test of nucleosynthesis models and models of Galactic chemical evolution. Ideally, such models should quantitatively explain the elemental and nuclide distributions of solar system matter.The sun has the most mass (>99%) of the solar system objects and therefore it is the prime target for studying solar system abundances. Most elements can be measured in the sun's photosphere, but data from the solar chromosphere and corona, solar energetic particles, solar wind, and solar cosmic rays (from solar flares), help to evaluate abundances of elements that have weak absorption lines (bec...

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“…The claimed accuracy of the absolute wavelength scale is ∼ 100 ms −1 (Kurucz 2005), However, this should be taken as an average value, since comparison of individual lines with synthetic spectra computed from hydrodynamical models of the stellar photosphere, that take into account the convective shifts, may show deviations as large as several hundreds m s −1 (see e.g. Caffau et al 2008).…”

Section: Solar-asteroid Comparisonmentioning

confidence: 99%

Fundamental constants and high‐resolution spectroscopy

et al. 2014

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Absorption-line systems detected in high resolution quasar spectra can be used to compare the value of dimensionless fundamental constants such as the fine-structure constant, α , and the proton-to-electron mass ratio, µ = mp/me, as measured in remote regions of the Universe to their value today on Earth. In recent years, some evidence has emerged of small temporal and also spatial variations in α on cosmological scales which may reach a fractional level of ≈ 10 ppm (parts per million). We are conducting a Large Programme of observations with the Very Large Telescope's Ultraviolet and Visual Echelle Spectrograph (UVES), and are obtaining high-resolution (R ≈ 60 000) and high signal-to-noise ratio (S/N ≈ 100) spectra calibrated specifically to study the variations of the fundamental constants. We here provide a general overview of the Large Programme and report on the first results for these two constants, discussed in detail in Molaro et al. and Rahmani et al.A stringent bound for ∆α/α is obtained for the absorber at z abs = 1.6919 towards HE 2217-2818. The absorption profile is complex with several very narrow features, and is modeled with 32 velocity components. The relative variation in α in this system is +1.3 ± 2.4stat ± 1.0sys ppm if Al II λ 1670Å and three Fe II transitions are used, and +1.1 ±2.6stat ppm in a slightly different analysis with only Fe II transitions used. This is one of the tightest bounds on α-variation from an individual absorber and reveals no evidence for variation in α at the 3-ppm precision level (1-σ confidence). The expectation at this sky position of the recently-reported dipolar variation of α is (3.2-5.4) ± 1.7 ppm depending on dipole model used and this constraint of ∆α/α at face value is not supporting this expectation but not inconsistent with it at the 3σ level. For the proton-to-electron mass ratio the analysis of the H2 absorption lines of the z abs ≈ 2.4018 damped Lyα system towards HE 0027-1836 provides ∆µ/µ = (−7.6 ± 8.1stat ± 6.3sys) ppm which is also consistent with a null variation. The cross-correlation analysis between individual exposures taken over three years and comparison with almost simultaneous asteroid observations revealed the presence of a possible wavelength dependent velocity drift as well as of inter-order distortions which probably dominate the systematic error and are a significant obstacle to achieve more accurate measurements.

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The solar photospheric abundance of hafnium and thorium

Cited by 31 publications

References 27 publications

The solar photospheric abundance of zirconium

The solar photospheric abundance of zirconium

Solar System Abundances of the Elements

Fundamental constants and high‐resolution spectroscopy

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