Accurate abundance patterns of solar twins and analogs

Abstract

We derive the abundance of 19 elements in a sample of 64 stars with fundamental parameters very similar to solar, which minimizes the impact of systematic errors in our spectroscopic 1D-LTE differential analysis, using high-resolution (R 60 000), high signalto-noise ratio (S /N 200) spectra. The estimated errors in the elemental abundances relative to solar are as small as 0.025 dex. The abundance ratios [X/Fe] as a function of [Fe/H] agree closely with previously established patterns of Galactic thin-disk chemical evolution. Interestingly, the majority of our stars show a significant correlation between [X/Fe] and condensation temperature (T C ). In the sample of 22 stars with parameters closest to solar, we find that, on average, low T C elements are depleted with respect to high T C elements in the solar twins relative to the Sun by about 0.08 dex ( 20%). An increasing trend is observed for the abundances as a function of T C for 900 < T C < 1800 K, while abundances of lower T C elements appear to be roughly constant. We speculate that this is a signature of the planet formation that occurred around the Sun but not in the majority of solar twins. If this hypothesis is correct, stars with planetary systems like ours, although rare (frequency of 15%), may be identified through a very detailed inspection of the chemical compositions of their host stars.

The GAPS programme with HARPS-N at TNG

“…Similarly to the analysis of several binary systems (see, e.g., Ramírez et al 2009Ramírez et al , 2011Schuler et al 2011b;Liu et al 2014;Mack et al 2014;Tucci Maia et al 2014), we find a positive trend with T C for the elemental abundances. Our results are consistent with accretion events of H-depleted rocky material in both components.…”

ζ2Reticuli, its debris disk, and its lonely stellar companionζ1Ret

“…Meléndez et al (2009) claimed that the Sun shows a deficiency in refractory elements with respect to other solar twins because these elements were trapped in the terrestrial planets in our solar system. The same conclusion was also reached by Ramírez et al (2009), who analyzed 64 solar twins and analogs with and without detected planets. However, later results by González and González Hernández et al (2013) strongly challenge the relation between the presence of planets and the abundance peculiarities of the stars.…”

Signatures of Earth-Like Planets in the Chemical Composition of Solar-Type Stars

“…This unprecedented precision was necessary to unravel the possible connection between abundance anomalies in the Sun and the formation of terrestrial planets Ramírez et al 2009), and to suggest a new abundance signature of giant planet formation (Ramírez et al 2011). Our on-going planet search around solar twins will allow us to study at unparalleled precision any connection that may exist between planet architecture and chemical abundance peculiarities.…”

“…The formation of terrestrial and gas giant planets has likely imprinted signatures on the chemical composition of their parent stars, as shown for example by the higher occurrence of giant planets for higher stellar metallicities. There are two new signatures that have been recently proposed by Meléndez et al (2009Meléndez et al ( , 2012 and Ramírez et al (2009Ramírez et al ( , 2010 for the formation of rocky planets, and by Ramírez et al (2011) for gas giant planets. We review here our on-going work on the planet-star connection using solar twins, for which chemical abundances are being obtained at unprecedented precision (0.01 dex).…”