| 1. |
- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 2. |
- Koposov, Sergey E., et al.
(författare)
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Kinematics and chemistry of recently discovered Reticulum 2 and Horologium 1 dwarf galaxies
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 811:1
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Tidskriftsartikel (refereegranskat)abstract
- We report on VLT/GIRAFFE spectra of stars in two recently discovered ultra-faint satellites, Reticulum 2 and Horologium 1, obtained as part of the Gaia-ESO Survey. We identify 18 members in Reticulum 2 and five in Horologium 1. We find Reticulum 2 to have a velocity dispersion of 3.22(-0.49)(+1.64) km s(-1) , implying a mass-to-light ratio (M/L) of similar to 500. The mean metallicity of Reticulum 2 is [Fe/H] = -2.46, with an intrinsic dispersion of similar to 0.3 dex and alpha-enhancement of similar to 0.4 dex. We conclude that Reticulum 2 is a dwarf galaxy. We also report on the serendipitous discovery of four stars in a previously unknown stellar substructure near Reticulum 2 with [Fe/H] similar to -2 and V-hel similar to 220 km s(-1), far from the systemic velocity of Reticulum 2. For Horologium 1 we infer a velocity dispersion of sigma (V) = 4.9(-0.9)(+2.8) km s(-1) and a M/L ratio of similar to 600, leading us to conclude that Horologium 1 is also a dwarf galaxy. Horologium 1 is slightly more metal-poor than Reticulum 2 ([Fe/H] = -2.76) and is similarly alpha-enhanced: [alpha/Fe] similar to 0.3 dex with a significant spread of metallicities of 0.17 dex. The line-of-sight velocity of Reticulum 2 is offset by 100 km s(-1) from the prediction of the orbital velocity of the Large Magellanic Cloud (LMC), thus making its association with the Cloud uncertain. However, at the location of Horologium 1, both the backward-integrated orbit of the LMC and its halo are predicted to have radial velocities similar to that of the dwarf. Therefore, it is possible that Horologium 1 is or once was a member of the Magellanic family.
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| 3. |
- Franchini, Mariagrazia, et al.
(författare)
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The Gaia-ESO Survey : Carbon Abundance in the Galactic Thin and Thick Disks
- 2020
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Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 888:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on carbon, which is one of the most abundant elements in the universe and is of high importance in the field of nucleosynthesis and galactic and stellar evolution. The origin of carbon and the relative importance of massive and low- to intermediate-mass stars in producing it is still a matter of debate. We aim at better understanding the origin of carbon by studying the trends of [C/H], [C/Fe], and [C/Mg] versus [Fe/H] and [Mg/H] for 2133 FGK dwarf stars from the fifth Gaia-ESO Survey internal data release (GES iDR5). The availability of accurate parallaxes and proper motions from Gaia DR2 and radial velocities from GES iDR5 allows us to compute Galactic velocities, orbits, absolute magnitudes, and, for 1751 stars, Bayesian-derived ages. Three different selection methodologies have been adopted to discriminate between thin- and thick-disk stars. In all the cases, the two stellar groups show different [C/H], [C/Fe], and [C/Mg] and span different age intervals, with the thick-disk stars being, on average, older than the thin-disk ones. The behaviors of [C/H], [C/Fe], and [C/Mg] versus [Fe/H], [Mg/H], and age all suggest that C is primarily produced in massive stars. The increase of [C/Mg] for young thin-disk stars indicates a contribution from low-mass stars or the increased C production from massive stars at high metallicities due to the enhanced mass loss. The analysis of the orbital parameters R-med and supports an "inside-out" and "upside-down" formation scenario for the disks of the Milky Way.
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