The r-Process Element Europium in Galactic Disk F and G Dwarf Stars

Woolf, Vincent M.; Tomkin, J.; Lambert, David L.

doi:10.1086/176428

Cited by 90 publications

(93 citation statements)

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“…The [Eu /Fe] ratio in Galactic metal-poor stars follows a trend similar to the alpha elements, increasing with decreasing [Fe/ H ] in the solar neighborhood, to a value near 0.3Y 0.4 dex and roughly flat below ½Fe/H $ À1 (McWilliam & Rich 1994;Woolf et al 1995). At the 47 Tuc metallicity the measured [Eu /Fe] ratio of Galactic stars ranges from 0.2 to 0.3 dex.…”

Section: Abundances Of Elements Other Than Ironmentioning

confidence: 75%

Globular Cluster Abundances from High‐Resolution Integrated‐Light Spectra. I. 47 Tuc

McWilliam

Bernstein

2008

Astrophysical Journal

133

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We describe the detailed chemical abundance analysis of a high-resolution (R $ 35;000), integrated-light ( IL), spectrum of the core of the Galactic globular cluster 47 Tuc, obtained using the du Pont echelle at Las Campanas. We develop an abundance analysis strategy that can be applied to spatial unresolved extragalactic clusters. We have computed abundances for Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Ba, La, Nd, and Eu. For an analysis with the known color-magnitude diagram (CMD) for 47 Tuc we obtain a mean [Fe/ H ] value of À0:75 AE 0:026 AE 0:045 dex (random and systematic error), in good agreement with the mean of five recent high-resolution abundance studies, at À0.70 dex. Typical random errors on our mean [ X / Fe] ratios are 0.07Y0.10 dex, similar to studies of individual stars in 47 Tuc. Na and Al appear enhanced, perhaps due to proton burning in the most luminous cluster stars. Our IL abundance analysis with an unknown CMD employed theoretical Teramo isochrones; however, we apply zero-point abundance corrections to account for the factor of 3 underprediction of stars at the AGB bump luminosity. While line diagnostics alone provide only mild constraints on the cluster age (ruling out ages younger than~2 Gyr), when theoretical IL B À V colors are combined with metallicity derived from the Fe i lines, the age is constrained to 10Y15 Gyr and we obtain ½Fe/H ¼ À0:70 AE 0:021 AE 0:052 dex. We find that Fe i line diagnostics may also be used to constrain the horizontal-branch morphology of an unresolved cluster. Lastly, our spectrum synthesis of 5.4 million TiO lines indicates that the 7300Y7600 8 TiO window should be useful for estimating the effect of M giants on the IL abundances, and important for clusters more metal-rich than 47 Tuc.

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Section: Abundances Of Elements Other Than Ironmentioning

confidence: 75%

Globular Cluster Abundances from High‐Resolution Integrated‐Light Spectra. I. 47 Tuc

McWilliam

Bernstein

2008

Astrophysical Journal

133

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“…The results indicate that except for the earliest phase ([Fe/H] < −2.5) double compact star mergers contribute 12 The observations are taken from Woolf et al (1995), Burris et al (2000) and Chen et al (2006). significantly to the chemical enrichment of r-process elements of the Galaxy. This enrichment is mainly due to the BH+NS binary mergers, while the double NS binary mergers (and the NS+BH mergers) only contribute marginally.…”

Section: Resultsmentioning

confidence: 99%

Massive double compact object mergers: gravitational wave sources and r-process element production sites

Mennekens

Vanbeveren

2014

A&A

173

197

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With our galactic evolutionary code that contains a detailed intermediate-mass and massive binary population model, we study the temporal evolution of the galactic population of double neutron star binaries, mixed systems with a neutron star and black hole component, and double black hole binaries. We computed the merger rates of these relativistic binaries and translate them into LIGO II detection rates. We demonstrate that accounting for the uncertainties in the relation "initial mass-final mass" predicted by massive close binary evolution and due to the possible effect of large stellar wind mass loss during the luminous blue variable phase of a star with initial mass higher than 30−40 M and during the red supergiant phase of a star with initial mass lower than 30−40 M when such a star is a binary component, the double black hole merger rate may be very low, contrary to predictions made by other groups. Hydrodynamic computations of the r-process chemical yields ejected during the relativistic binary merger process have recently become available. With our galactic code that includes binaries, it is then straightforward to calculate the temporal galactic evolution of the r-process elements ejected by these mergers. We conclude that except for the earliest evolutionary phase of the Galaxy (∼the first 100 Myr), double compact star mergers may be the major production sites of r-process elements, and it is probable that the mixed systems dominate this production over double neutron star binary mergers.

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“…Gratton & Sneden (1994), Burris et al (2000), Jehin et al (1999), Woolf et al (1995), andMashonkina &Gehren (2001) provide an increasing linear relation between log (Eu) and [Fe/H]. On the other hand, [Eu/Fe] decreases toward higher metallicities.…”

Section: The R-elementsmentioning

confidence: 99%

Analysis of 26 barium stars

Allen

Barbuy

2006

A&A

157

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Context. We present a detailed analysis of 26 barium stars, including dwarf barium stars, providing their atmospheric parameters (T eff , log g, [Fe/H], v t ), and elemental abundances. Aims. We aim at deriving gravities and luminosity classes of the sample stars, in particular to confirm the existence of dwarf barium stars. Accurate abundances of chemical elements were derived. We present the abundance ratios between nucleosynthetic processes, by using Eu and Ba as representatives of the r-and s-processes. Methods. High-resolution spectra were obtained with the FEROS spectrograph at the ESO-1.52 m Telescope, along with photometric data with Fotrap at the Zeiss telescope at the LNA. The atmospheric parameters were derived in an iterative way, with temperatures obtained from colour-temperature calibrations. The abundances were derived using spectrum synthesis for Li, Na, Al, α-, iron-peak, s-, and r-element atomic lines, and for C and N molecular lines. Results. Atmospheric parameters in the range 4300 < T eff < 6500, −1.2 < [Fe/H] < 0.0, and 1.4 ≤ log g < 4.6 were derived, confirming that our sample contains giants, subgiants, and dwarfs. The abundance results obtained for Li, Al, Na, α-, and iron-peak elements for the sample stars show that they are compatible with the values found in the literature for normal disk stars in the same range of metallicities. Enhancements of C, N, and heavy elements relative to Fe, that characterise barium stars, were derived and showed that [X/Ba]

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The r-Process Element Europium in Galactic Disk F and G Dwarf Stars

Cited by 90 publications

References 0 publications

Globular Cluster Abundances from High‐Resolution Integrated‐Light Spectra. I. 47 Tuc

Globular Cluster Abundances from High‐Resolution Integrated‐Light Spectra. I. 47 Tuc

Massive double compact object mergers: gravitational wave sources and r-process element production sites

Analysis of 26 barium stars

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