Stellar Archaeology: A Keck Pilot Program on Extremely Metal-Poor Stars From the Hamburg/ESO Survey. III. The Lead (P[CLC]b[/CLC]) Star HE 0024−2523

Lucatello, S.; Gratton, R.; Cohen, Judith G.; Beers, Timothy C.; Christlieb, N.; Carretta, E.; Ramírez, Solange

doi:10.1086/345886

Cited by 129 publications

(154 citation statements)

References 73 publications

(91 reference statements)

Supporting

Mentioning

147

Contrasting

Unclassified

Order By: Relevance

“…For the CH and CN molecular bands, we used the Kurucz molecular linelists 6 , but we had to revise the log g f values of C downwards 4 http://physics.nist.gov/PhysRefData/ASD/index.html 5 We could not use the 5872 Å Cu I line since it falls into the gap between the two UVES red CCDs. 6 http://kurucz.harvard.edu/LINELISTS/LINESMOL/ by 0.3 dex, similarly to what was reported by Bonifacio et al (1998), Lucatello et al (2003), and Spite et al (2005) (see also Sect. 3.3).…”

Section: Equivalent Widths and Atomic Datasupporting

confidence: 86%

The subgiant branch ofω Centauri seen through high-resolution spectroscopy

Pancino¹,

Mucciarelli²,

Sbordone³

et al. 2011

A&A

View full text Add to dashboard Cite

We analysed high-resolution UVES spectra of six stars belonging to the subgiant branch of ω Centauri, and derived abundance ratios of 19 chemical elements (namely Al, Ba, C, Ca, Co, Cr, Cu, Fe, La, Mg, Mn, N, Na, Ni, Sc, Si, Sr, Ti, and Y). A comparison with previous abundance determinations for red giants provided remarkable agreement and allowed us to identify the sub-populations to which our targets belong. We found that three targets belong to a low-metallicity population at [Fe/H] -2.0 dex, [α/Fe] +0.4 dex and [s/Fe] 0 dex. Stars with similar characteristics were found in small amounts by past surveys of red giants. We discuss the possibility that they belong to a separate sub-population that we name VMP (very metal-poor, at most 5% of the total cluster population), which -in the self-enrichment hypothesis -is the best-candidate first stellar generation in ω Cen. Two of the remaining targets belong to the dominant metal-poor population (MP) at [Fe/H] -1.7 dex, and the last one to the metal-intermediate (MInt) one at [Fe/H] -1.2 dex. The existence of the newly defined VMP population could help to understand some puzzling results based on low-resolution spectroscopy for age differences determinations, because the metallicity resolution of these studies was probably not enough to detect the VMP population. The VMP could also correspond to some of the additional substructures of the subgiant-branch region found in the latest HST photometry. After trying to correlate chemical abundances with substructures in the subgiant branch of ω Cen, we found that the age difference between the VMP and MP populations should be small (0 ± 2 Gyr), while the difference between the MP and MInt populations could be slightly larger (2 ± 2 Gyr).

show abstract

Section: Equivalent Widths and Atomic Datasupporting

confidence: 86%

The subgiant branch ofω Centauri seen through high-resolution spectroscopy

Pancino¹,

Mucciarelli²,

Sbordone³

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…HE 1046−1352, with a period of only 20 days, does have the expected circular orbit, but the calculated Roche-lobe radii for an average-mass white dwarf secondary are too small to accommodate even a normal giant star, let alone an AGB star of ≈200 R . HE 1046−1352 could be a misclassified dwarf or the result of a common-envelope phase of evolution, similar to the even shorter-period system HE 0024−2523 discussed by Lucatello et al (2003) on the basis of its high spectroscopic log g, remarkable abundance pattern, and high rotation.…”

Section: Binary Fraction and Distribution Of Orbital Eccentricitiesmentioning

confidence: 84%

“…In some systems, a common-envelope phase is even needed to shrink the orbits to their current size. This is particularly true for the binary system HE 0024−2523, with a period of only 3.41 days (Lucatello et al 2003).…”

Section: Mass-transfer Mechanismsmentioning

confidence: 99%

The role of binaries in the enrichment of the early Galactic halo

Hansen

Andersen

Nordström

et al. 2016

A&A

143

146

View full text Add to dashboard Cite

Context. Detailed spectroscopic studies of metal-poor halo stars have highlighted the important role of carbon-enhanced metal-poor (CEMP) stars in understanding the early production and ejection of carbon in the Galaxy and in identifying the progenitors of the CEMP stars among the first stars formed after the Big Bang. Recent work has also classified the CEMP stars by absolute carbon abundance, A(C), into high-and low-C bands, mostly populated by binary and single stars, respectively. Aims. Our aim is to determine the frequency and orbital parameters of binary systems among the CEMP-s stars, which exhibit strong enhancements of neutron-capture elements associated with the s-process. This allows us to test whether local mass transfer from a binary companion is necessary and sufficient to explain their dramatic carbon excesses. Methods. We have systematically monitored the radial velocities of a sample of 22 CEMP-s stars for several years with ∼monthly, high-resolution, low S/N échelle spectra obtained at the Nordic Optical Telescope (NOT) at La Palma, Spain. From these spectra, radial velocities with an accuracy of ≈100 m s −1 were determined by cross-correlation with optimised templates. Results. Eighteen of the 22 stars exhibit clear orbital motion, yielding a binary frequency of 82 ± 10%, while four stars appear to be single (18 ± 10%). We thus confirm that the binary frequency of CEMP-s stars is much higher than for normal metal-poor giants, but not 100% as previously claimed. Secure orbits are determined for eleven of the binaries and provisional orbits for six long-period systems (P > 3000 days), and orbital circularisation timescales are discussed. Conclusions. The conventional scenario of local mass transfer from a former asymptotic giant branch (AGB) binary companion does appear to account for the chemical composition of most CEMP-s stars. However, the excess of C and s-process elements in some single CEMP-s stars was apparently transferred to their natal clouds by an external (distant) source. This finding has important implications for our understanding of carbon enrichment in the early Galactic halo and some high-redshift damped lyman alpha (DLA) systems, and of the mass loss from extremely metal-poor AGB stars.

show abstract

“…The definition of "s" varies from author to author and in some cases depends on the quality and/or on the wavelength range of the available spectra. Among CEMP stars, there are six that are binaries: CS 22942-019, CS 22948-027, CS 29497-030, CS 29497-034, CS 22964-161, and HE 0024-2523, the data of which concerning their carbon and heavy-element (Z > 56) overabundances and binarity were taken from the results of Preston & Sneden (2001); Sivarani et al (2004); Barbuy et al (2005); Lucatello et al (2003); Thompson et al (2008); Aoki et al (2002) and Hill et al (2000). According to the mass-transfer hyphotesis for the origin of the barium stars, one of the binary components ejects its envelope that is enriched in the s-process elements produced during the AGB phase, and this matter falls onto the companion, which in turn becomes enriched in these elements, and now is the barium star.…”

Section: Sodium To Nickelmentioning

confidence: 99%

Chemical abundances and kinematics of a sample of metal-rich barium stars

Pereira

Silva

Chavero

et al. 2011

A&A

View full text Add to dashboard Cite

Aims. We determined the atmospheric parameters and abundance pattern for a sample of metal-rich barium stars. Methods. We used high-resolution optical spectroscopy. Atmospheric parameters and abundances were determined using the local thermodynamic equilibrium atmosphere models of Kurucz and the spectral analysis code MOOG. Results. We show that the stars have enhancement factors, [s/Fe], from 0.25 to 1.16. Their abundance pattern of the Na, Al, α-elements, and iron group elements as well as their kinematical properties are similar to the characteristics of the other metal-rich and super metal-rich stars already analyzed. We conclude that metal-rich barium stars do not belong to the bulge population. We also show that metal-rich barium stars are useful targets for probing the s-process enrichment in high-metallicity environments.

show abstract

Stellar Archaeology: A Keck Pilot Program on Extremely Metal-Poor Stars From the Hamburg/ESO Survey. III. The Lead (P[CLC]b[/CLC]) Star HE 0024−2523

Cited by 129 publications

References 73 publications

The subgiant branch ofω Centauri seen through high-resolution spectroscopy

The subgiant branch ofω Centauri seen through high-resolution spectroscopy

The role of binaries in the enrichment of the early Galactic halo

Chemical abundances and kinematics of a sample of metal-rich barium stars

Contact Info

Product

Resources

About