Spectroscopic Studies of Extremely Metal‐Poor Stars with the Subaru High Dispersion Spectrograph. I. Observational Data

Honda, Satoshi; Aoki, Wako; Ando, Hiroyasu; Izumiura, Hideyuki; Kajino, Toshitaka; Kambe, Eiji; Kawanomoto, Satoshi; Noguchi, Kunio; Okita, Kiichi; Sadakane, Kozo; Sato, B.; Takada-Hidai, Masahide; Takeda, Yoichi; Watanabe, E.; Beers, Timothy C.; Norris, John E.; Ryan, Sean G.

doi:10.1086/383201

Cited by 43 publications

(47 citation statements)

References 51 publications

(103 reference statements)

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“…From the five V I transitions we obtain A(V) = +1.35 ± 0.10 dex, while the seven V II lines give A(V) = +1.72 ± 0.10 dex, higher than the result from nonionized state. Finally, using the complete set of lines we obtain A(V) = +1.56 ± 0.11 dex as the final abundance, in excellent agreement with A(V) = +1.55 from Honda et al (2004), derived in their analysis from three lines (marked with an asterisk in Table 3). …”

Section: Verification Of Blendssupporting

confidence: 83%

“…Figure 3 shows the fit of the observed lines of CH AX electronic transition band (G band) in HD 140283. One can see that the spectrum is well-described by the model using the carbon abundance A(C) = +6.30 dex adopted from Honda et al (2004). Indeed, several CH bands were analysed and all of them presented a good fit, therefore we assume that they are properly taken into account and have no influence on the derivation of the europium abundance.…”

Section: Verification Of Blendsmentioning

confidence: 85%

“…Following Gallagher et al (2010), we adopted the stellar parameters T eff = 5750 ± 100 K, [Fe/H] = −2.5 ± 0.2 and v t = 1.4±0.1 km s −1 from Aoki et al (2004) and log g = 3.7±0.1 [cgs] from Collet et al (2009). We also adopted the element abundances determined by Honda et al (2004).…”

Section: Atmospheric Parameters and Spectrum Synthesismentioning

confidence: 99%

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Origin of the heavy elements in HD 140283

Mello¹,

Barbuy²,

Spite³

et al. 2012

A&A

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Context. HD 140283 is a nearby (V = 7.7) subgiant metal-poor star, extensively analysed in the literature. Although many spectra have been obtained for this star, none showed a signal-to-noise (S/N) ratio high enough to enable a very accurate derivation of abundances from weak lines. Aims. The detection of europium proves that the neutron-capture elements in this star originate in the r-process, and not in the s-process, as recently claimed in the literature. Methods. Based on the OSMARCS 1D LTE atmospheric model and with a consistent approach based on the spectrum synthesis code Turbospectrum, we measured the europium lines at 4129 Å and 4205 Å, taking into account the hyperfine structure of the transitions. The spectrum, obtained with a long exposure time of seven hours at the Canada-France-Hawaii Telescope (CFHT), has a resolving power of 81 000 and a S/N ratio of 800 at 4100 Å. Results. We were able to determine the abundance A(Eu) = −2.35 ± 0.07 dex, compatible with the value predicted for the europium from the r-process. The abundance ratio [Eu/Ba] = +0.58 ± 0.15 dex agrees with the trend observed in metal-poor stars and is also compatible with a strong r-process contribution to the origin of the neutron-capture elements in HD 140283.

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Section: Verification Of Blendssupporting

confidence: 83%

Section: Verification Of Blendsmentioning

confidence: 85%

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Origin of the heavy elements in HD 140283

Mello¹,

Barbuy²,

Spite³

et al. 2012

A&A

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“…However, Th is further enhanced relative to this pattern in four stars: CS 31082-001, CS 30306-132 (Honda et al 2004), CS 31078-018 (Lai et al 2008) and HE 1219-0312 (Hayek et al 2009) -the so-called "actinide boost". In these stars, the actinides clearly had a different nucleosynthesis history than the stable third-peak elements.…”

Section: The R-element-rich Emp Stars and The Actinidesmentioning

confidence: 94%

“…The star CS 22183-031 at [Fe/H] = −2.93 and [r/Fe] = +1.2 (Honda et al 2004) is an example of a somewhat milder r-element enhancement.…”

Section: The R-element-rich Emp Stars and The Actinidesmentioning

confidence: 99%

First stars

Barbuy

Spite

Hill

et al. 2011

A&A

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Context. A small fraction of extremely metal-poor (EMP) stars exhibit moderate to extreme excesses of heavy neutron-capture elements produced in the r-process. The production site(s) of these elements in the early Galaxy remain(s) unclear, as is the reason for their occasional enhancement in the otherwise regular pattern of abundances of elements up to the iron peak. The detailed abundance pattern of the heaviest elements in EMP stars provides insight into their origin and role in the chemical enrichment of the early Galaxy and in radioactive nucleochronology. Aims. The EMP giant star CS 31082-001 ([Fe/H] ∼ −2.9) exhibits an extreme enhancement of neutron-capture elements ([r/Fe] ∼ +1.7) with U and Th enhanced by a further ∼+0.7 dex, and a minimum of blending by molecular lines such as CH or CN. A rich inventory of r-process element abundances was established previously from optical spectra. Here we aim to supplement these data with abundances from near-UV spectroscopy of the third-peak neutron-capture elements, which are crucial for understanding the synthesis of the heaviest elements. Methods. Near-UV spectra from HST/STIS were analysed with LTE model atmospheres and spectrum synthesis calculations to derive new abundances of Os, Ir, Pt, Au, Bi and Pb in CS 31082-001. Results. Together with earlier data, the resulting abundance pattern for the r-process elements provides improved constraints on the nature of the r-process. The observed U and Th abundances and the initial production ratio place CS 31082-001 as one of the oldest stars in the Galaxy, consistent with its extreme metal deficiency. Comparison with the heaviest stable reference elements and with the daughter nuclides Pb and Bi provides a consistency check on this age determination. Finally, the existence of such r-element rich stars indicate that the early chemical evolution of the Galaxy was localised and inhomogeneous.

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