Chemical Inhomogeneities in the Pleiades: Signatures of Rocky-forming Material in Stellar Atmospheres

Spina, L.; Meléndez, Jorge; Casey, Andrew R.; Karakas, Amanda I.; Tucci-Maia, Marcelo

doi:10.3847/1538-4357/aad190

Cited by 36 publications

(30 citation statements)

References 55 publications

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“…High-precision chemical analyses of twin-star binaries have revealed statistically-significant differences of 0.05 dex, with a couple of extreme cases where the differences amount to about 0.20 dex, 1 including the system investigated in this work. These values are comparable to the chemical abundance inhomogeneities (star-to-star scatter) found in high-precision studies ( 0.01 dex errors in relative abundances) of stars in open clusters like the Hyades (Liu et al 2016), Pleiades (Spina et al 2018), and M67 (Liu et al 2019). We must note, however, that strictly speaking the stellar pairs utilized in this type of binary studies are by definition comoving objects.…”

Section: Introductionsupporting

confidence: 79%

The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs

Ramírez

Khanal

Lichon

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We conducted a high-precision elemental abundance analysis of the twin-star comoving pair HIP 34407/HIP 34426. With mean error of 0.013 dex in the differential abundances (∆[X/H]), a significant difference was found: HIP 34407 is more metal-rich than HIP 34426. The elemental abundance differences correlate strongly with condensation temperature, with the lowest for the volatile elements like carbon around 0.05 ± 0.02 dex, and the highest up to about 0.22 ± 0.01 dex for the most refractory elements like aluminum. Dissimilar chemical composition for stars in twin-star comoving pairs are not uncommon, thus we compile previously-published results like ours and look for correlations between abundance differences and stellar parameters, finding no significant trends with average effective temperature, surface gravity, iron abundance, or their differences. Instead, we found a weak correlation between the absolute value of abundance difference and the projected distance between the stars in each pair that appears to be more important for elements which have a low absolute abundance. If confirmed, this correlation could be an important observational constraint for binary star system formation scenarios.1 In this work, we adopt the standard "bracket" chemical abundance notation [X/H] = A(X)− A(X) , where A(X) = log(n X /n H )+12 and n X is the number density of species X in the star's photosphere.

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Section: Introductionsupporting

confidence: 79%

The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs

Ramírez

Khanal

Lichon

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…This indicates that Y535 might has a wide binary companion, although it is diffi- Combining the fact that all three turn-off stars are high probability members of M67, our results imply that the turn-off stars in M67 are chemically inhomogeneous. This phenomenon has been reported for main-sequence dwarf stars in the Hyades (Liu et al 2016a) and in the Pleiades (Spina et al 2018), although those results were explained using different scenarios. Further discussion about abundance trends versus dust condensation temperature for our results are presented in Appendix B.…”

Section: Elemental Abundances Of Turn-off Stars In M67supporting

confidence: 66%

“…This could lead to changes in the surface abundance of some elements. Spina et al (2018) conducted a high-precision spectroscopic study of five members of the open cluster Pleiades and reported variations in the elemental abundances. They attributed the observed chemical inhomogeneity to the process of forming planets, since the abundance differences correlate with condensation temperature Article number, page 1 of 19 of the elements analysed.…”

Section: Introductionmentioning

confidence: 99%

Chemical (in)homogeneity and atomic diffusion in the open cluster M 67

Liu

Asplund

Yong

et al. 2019

A&A

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Context.The benchmark open cluster M67 is known to have solar metallicity and similar age as the Sun. It thus provides us a great opportunity to study the properties of solar twins, as well as the evolution of Sun-like stars. Aims. Previous spectroscopic studies reported to detect possible subtle changes in stellar surface abundances throughout the stellar evolutionary phase, namely the effect of atomic diffusion, in M67. In this study we attempt to confirm and quantify more precisely the effect of atomic diffusion, as well as to explore the level of chemical (in)homogeneity in M67. Methods. We presented a strictly line-by-line differential chemical abundance analysis of two groups of stars in M67: three turn-off stars and three sub-giants. Stellar atmospheric parameters and elemental abundances were obtained with very high precision using the Keck/HIRES spectra. Results. The sub-giants in our sample show negligible abundance variations (≤ 0.02 dex), which implies that M67 was born chemically homogeneous. We note there is a significant abundance difference (∼ 0.1 -0.2 dex) between sub-giants and turn-off stars, which can be interpreted as the signature of atomic diffusion. Qualitatively stellar models with diffusion agree with the observed abundance results. Some turn-off stars do not follow the general pattern, which suggests that in some cases diffusion can be inhibited, or they might suffered some sort of mixing event related to planets. Conclusions. Our results pose additional challenges for chemical tagging when using turn-off stars. In particular, the effects of atomic diffusion, which could be as large as 0.1 -0.2 dex, must be taken into account in order for chemical tagging to be successfully applied.

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“…For open clusters several studies have been devoted to the search for abundance differences among cluster stars with negative or non-significant results. A first sign of chemical inhomogeneities at the 0.02 -0.04 dex level among the solar-type stars in the Hyades and Pleiades clusters was, however, reported by Liu et al (2016b) and Spina et al (2018a). 5.…”

Section: Introductionmentioning

confidence: 88%

High-precision stellar abundances of the elements: methods and applications

Nissen

Gustafsson

2018

Astron Astrophys Rev

101

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Efficient spectrographs at large telescopes have made it possible to obtain high-resolution spectra of stars with high signal-to-noise ratio and advances in model atmosphere analyses have enabled estimates of high-precision differential abundances of the elements from these spectra, i.e. with errors in the range 0.01 -0.03 dex for F, G, and K stars.Methods to determine such high-precision abundances together with precise values of effective temperatures and surface gravities from equivalent widths of spectral lines or by spectrum synthesis techniques are outlined, and effects on abundance determinations from using a 3D non-LTE analysis instead of a classical 1D LTE analysis are considered.The determination of high-precision stellar abundances of the elements have led to the discovery of unexpected phenomena and relations with important bearings on the astrophysics of galaxies, stars, and planets, i.e. i) Existence of discrete stellar populations within each of the main Galactic components (disk, halo, and bulge) providing new constraints on models for the formation of the Milky Way. ii) Differences in the relation between abundances and elemental condensation temperature for the Sun and solar twins suggesting dust-cleansing effects in proto-planetary disks and/or engulfment of planets by stars; iii) Differences in chemical composition between binary star components and between members of open or globular clusters showing that star-and cluster-formation processes are more complicated than previously thought; iv) Tight relations between some abundance ratios and age for solar-like stars providing new constraints on nucleosynthesis and Galactic chemical evolution models as well as the composition of terrestrial exoplanets.We conclude that if stellar abundances with precisions of 0.01 -0.03 dex can be achieved in studies of more distant stars and stars on the giant and supergiant branches, many more interesting future applications, of great relevance to stellar and galaxy evolution, are probable. Hence, in planning abundance surveys, it is important to carefully balance the need for large samples of stars against the spectral resolution and signal-to-noise ratio needed to obtain high-precision abundances. Furthermore, it is an advantage to work differentially on stars with similar atmospheric parameters, because then a simple 1D LTE analysis of stellar spectra may be sufficient. However, when determining high-precision absolute abundances or differential abundance between stars having more widely different parameters, e.g. metal-poor stars compared to the Sun or giants to dwarfs, then 3D non-LTE effects must be taken into account.

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Chemical Inhomogeneities in the Pleiades: Signatures of Rocky-forming Material in Stellar Atmospheres

Cited by 36 publications

References 55 publications

The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs

The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs

Chemical (in)homogeneity and atomic diffusion in the open cluster M 67

High-precision stellar abundances of the elements: methods and applications

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