L. Spina

Planet signatures and effect of the chemical evolution of the Galactic thin-disk stars

Context: Studies based on high-precision abundance determinations revealed that chemical patterns of solar twins are characterised by the correlation between the differential abundances relative to the Sun and the condensation temperatures (Tc) of the elements. It has been suggested that the origin of this relation is related to the chemical evolution of the Galactic disk, but other processes, associated with the presence of planets around stars, might also be involved. Aims: We analyse HIRES spectra of 14 solar twins and the Sun to provide new insights on the mechanisms that can determine the relation between [X/H] and Tc. Methods: Our spectroscopic analysis produced stellar parameters (Teff, log g, [Fe/H], and

Nucleosynthetic history of elements in the Galactic disk - [X/Fe]–age relations from high-precision spectroscopy

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Gaia-ESO Survey: Analysis of pre-main sequence stellar spectra

), ages, masses, and abundances of 22 elements (C, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, and Ba). We used these determinations to place new constraints on the chemical evolution of the Galactic disk and to verify whether this process alone can explain the different [X/H]-Tc slopes observed so far. Results: We confirm that the [X/Fe] ratios of all the species correlate with age. The slopes of these relations allow us to describe the effect that the chemical evolution of the Galactic disk has on the chemical patterns of the solar twins. After subtracting the chemical evolution effect, we find that the unevolved [X/H]-Tc slope values do not depend on the stellar ages anymore. However, the wide diversity among these [X/H]-Tc slopes, covering a range of

The Gaia-ESO Survey: radial distribution of abundances in the Galactic disc from open clusters and young-field stars

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The Solar Twin Planet Search - II. A Jupiter twin around a solar twin

4~10

The Gaia-ESO Survey: Structural and dynamical properties of the young cluster Chamaeleon I

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The solar twin planet search : IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars

dex K

The Gaia-ESO Survey : the present-day radial metallicity distribution of the Galactic disc probed by pre-main-sequence clusters

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The Gaia-ESO Survey: Galactic evolution of sulphur and zinc

, indicates that processes in addition to the chemical evolution may affect the [X/H]-Tc slopes. Conclusions: The wide range of unevolved [X/H]-Tc slope values spanned at all ages by our sample could reflect the wide diversity among exo-planetary systems observed so far and the variety of fates that the matter in circumstellar disks can experience.

The Gaia-ESO Survey: chemical signatures of rocky accretion in a young solar-type star

Context. The chemical composition of stars is intimately linked to the formation and evolution of the Galaxy. Aims. We aim to trace the chemical evolution of the Galactic disk through the inspection of the [X/Fe]–age relations of 24 species from C to Eu. Methods. Using high-resolution and high signal-to-noise UVES spectra of nine solar twins, we obtained precise estimates of stellar ages and chemical abundances. These determinations have been integrated with additional accurate age and abundance determinations from recent spectroscopic studies of solar twins existing in the literature, comprising superb abundances with 0.01 dex precision. Based on this data set, we outlined the [X/Fe]–age relations over a time interval of 10 Gyr. Results. We present the [X/Fe] – age relations for 24 elements (C, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Ba, La, Ce, Nd, and Eu). Each different class of elements showed a distinct evolution with time that relies on the different characteristics, rates, and timescales of the nucleosynthesis sites from which they are produced. The α -elements are characterized by a [X/Fe] decrease with time. Strikingly, the opposite behavior is observed for Ca. The iron-peak elements show an early [X/Fe] increase followed by a decrease towards the youngest stars. The [X/Fe] for the n -capture elements decrease with age. We also found that both [Mg/Y] and [Al/Y] are precise stellar clocks, with [Al/Y] showing the steepest dependence on age. Conclusions. Knowledge of the [X/Fe]-age relations is a gold mine from which we can achieve a great understanding of the processes that governed the formation and evolution of the Milky Way. Through the reverse engineering of these relations we will be able to put strong constraints on the nature of the stellar formation history, the SNe rates, the stellar yields, and the variety of the SNe progenitors.