The GAPS Programme at TNG

Baratella, M.; D’Orazi, V.; Biazzo, K.; Desidera, S.; Gratton, R. G.; Benatti, S.; Bignamini, A.; Carleo, I.; Cecconi, M.; Claudi, R.; Cosentino, R.; Ghedina, A.; Harutyunyan, A.; Lanza, A. F.; Malavolta, L.; Maldonado, J.; Mallonn, M.; Messina, S.; Micela, G.; Molinari, E.; Poretti, E.; Scandariato, G.; Sozzetti, A.

doi:10.1051/0004-6361/202038511

Cited by 21 publications

(25 citation statements)

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“…It has been observed that strong ionised lines of Fe, Ti, and Cr yield large abundances in young and cool (T eff < 5400 K) stars (see e.g. D 'Orazi et al 2009;Schuler et al 2010;Tsantaki et al 2019;Baratella et al 2020a). This is referred to as the ionisation balance problem.…”

Section: Behaviour Of Spectral Linesmentioning

confidence: 99%

The Gaia-ESO Survey: a new approach to chemically characterising young open clusters

Baratella

D’Orazi

Sheminova

et al. 2021

A&A

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Context. Young open clusters (ages of less than 200 Myr) have been observed to exhibit several peculiarities in their chemical compositions. These anomalies include a slightly sub-solar iron content, super-solar abundances of some atomic species (e.g. ionised chromium), and atypical enhancements of [Ba/Fe], with values up to ~0.7 dex. Regarding the behaviour of the other s-process elements like yttrium, zirconium, lanthanum, and cerium, there is general disagreement in the literature: some authors claim that they follow the same trend as barium, while others find solar abundances at all ages. Aims. In this work we expand upon our previous analysis of a sample of five young open clusters (IC 2391, IC 2602, IC 4665, NGC 2516, and NGC 2547) and one star-forming region (NGC 2264), with the aim of determining abundances of different neutron-capture elements, mainly Cu I, Sr I, Sr II, Y II, Zr II, Ba II, La II, and Ce II. For NGC 2264 and NGC 2547 we present the measurements of these elements for the first time. Methods. We analysed high-resolution, high signal-to-noise spectra of 23 solar-type stars observed within the Gaia-ESO survey. After a careful selection, we derived abundances of isolated and clean lines via spectral synthesis computations and in a strictly differential way with respect to the Sun. Results. We find that our clusters have solar [Cu/Fe] within the uncertainties, while we confirm that [Ba/Fe] is super-solar, with values ranging from +0.22 to +0.64 dex. Our analysis also points to a mild enhancement of Y, with [Y/Fe] ratios covering values between 0 and +0.3 dex. For the other s-process elements we find that [X/Fe] ratios are solar at all ages. Conclusions. It is not possible to reconcile the anomalous behaviour of Ba and Y at young ages with standard stellar yields and Galactic chemical evolution model predictions. We explore different possible scenarios related to the behaviour of spectral lines, from the dependence on the different ionisation stages and the sensitivity to the presence of magnetic fields (through the Landé factor) to the first ionisation potential effect. We also investigate the possibility that they may arise from alterations of the structure of the stellar photosphere due to the increased levels of stellar activity that affect the spectral line formation, and consequently the derived abundances. These effects seem to be stronger in stars at ages of less than ~ 100 Myr. However, we are still unable to explain these enhancements, and the Ba puzzle remains unsolved. With the present study we suggest that other elements, for example Sr, Zr, La, and Ce, might be more reliable tracer of the s-process at young ages, and we strongly encourage further critical observations.

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Section: Behaviour Of Spectral Linesmentioning

confidence: 99%

The Gaia-ESO Survey: a new approach to chemically characterising young open clusters

Baratella

D’Orazi

Sheminova

et al. 2021

A&A

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“…Carbon abundances were derived by spectral synthesis of the CH molecular band at 430 nm using the CH line list provided in Masseron et al (2014). These abundances are expressed relative to the solar value obtained in Baratella et al (2020). Oxygen abundances were derived by spectral fitting of the [O I] 630 nm line.…”

Section: Stellar Parameters and Chemical Abundances Of The Fgk Primariesmentioning

confidence: 99%

HADES RV programme with HARPS-N at TNG

Maldonado

Micela

Baratella

et al. 2020

A&A

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Context. Most of our current knowledge on planet formation is still based on the analysis of main sequence, solar-type stars. Conversely, detailed chemical studies of large samples of M dwarfs hosting planets are still missing. Aims. Correlations exist between the presence of different types of planets around FGK stars and metallicity, individual chemical abundance, and stellar mass. We aim to test whether or not these correlations still hold for the less-massive M dwarf stars. Methods to determine stellar abundances of M dwarfs from high-resolution optical spectra in a consistent way are still missing. The present work is a first attempt to fill this gap. Methods. We analyse a large sample of M dwarfs with and without known planetary companions in a coherent and homogeneous way. We develop for the first time a methodology to determine stellar abundances of elements other than iron for M dwarf stars from high-resolution optical spectra. Our methodology is based on the use of a principal component analysis and sparse Bayesian methods. We made use of a set of M dwarfs orbiting around an FGK primary with known abundances to train our methods. We applied our methods to derive stellar metalliticies and abundances of a large sample of M dwarfs observed within the framework of current radial-velocity surveys. We then used a sample of nearby FGK stars to cross-validate our technique by comparing the derived abundance trends in the M dwarf sample with those found on the FGK stars. Results. The metallicity distribution of the different subsamples reveals a correlation between the metallicities of M dwarfs and their probability of hosting giant planets. We also find a correlation between this latter probability and stellar mass. M dwarfs hosting low-mass planets do not seem to follow the so-called planet–metallicity correlation. We also find that the frequency of low-mass planets does not depend on the mass of the stellar host. These results appear to be in agreement with those of previous works. However, we note that for giant-planet hosts our metallicities predict a weaker planet–host metallicity correlation but a stronger mass-dependency than corresponding values derived from photometric results. We show for the first time that there seems to be no differences between M dwarfs with and without known planets in terms of their abundance distributions of elements different from iron. Conclusions. Our data show that low-mass stars with planets follow the same metallicity, mass, and abundance trends as their FGK counterparts, which are usually explained within the framework of core-accretion models.

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“…NGC 2682 (M67) -This is one of the most studied open clusters and has solar metallicity and age (see e.g. Bertelli Motta et al 2018;. We observed four stars, two on the red clump and single, and two red giants known to be binary systems (see Tables 2 and 5).…”

Section: Comparison With Literaturementioning

confidence: 83%

“…In this case two stars are in common with our sample, as they were targeted on purpose. However, only one (Tombaugh 5_1 for us, 7701 in Baratella et al 2018) is analyzed in both papers, as they considered the second (Tombaugh 5_2 for us, 8099 in Baratella et al 2018) a possible non member on the basis of its RV and previous literature. The latter star has a high probability of be-ing a member according to and the RVs measured by us and Gaia RVS upport its membership.…”

Section: Comparison With Literaturementioning

confidence: 99%

“…Jeffries et al 2014;Mapelli et al 2015) and the evolution of the stars properties following changes in rotation, activity, surface abundances, all key constraints to modern stellar evolutionary models (see e.g. Bertelli Motta et al 2018;Smiljanic et al 2016;Lagarde et al 2019, on diffusion and extra mixing). However, because of their spectral coverage and/or resolution, these surveys provide an incomplete chemical characterization of OC stars.…”

Section: Introductionmentioning

confidence: 99%

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Stellar Population Astrophysics (SPA) with TNG Atmospheric parameters of members of 16 unstudied open clusters

Zhang,

Lucatello,

Bragaglia

et al. 2021

Preprint

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Context. Thanks to modern understanding of stellar evolution, we can accurately measure the age of Open Clusters (OCs). Given their position, they are ideal tracers of the Galactic disc. Gaia data release 2, besides providing precise parallaxes, led to the detection of many new clusters, opening a new era for the study of the Galactic disc. However, detailed information on the chemical abundance for OCs is necessary to accurately date them and to efficiently use them to probe the evolution of the disc. Aims. Mapping and exploring the Milky Way structure is the main aim of the Stellar Population Astrophysics (SPA) project. Part of this work involves the use of OCs and the derivation of their precise and accurate chemical composition. We analyze here a sample of OCs located within about 2 kpc from the Sun, with ages from about 50 Myr to a few Gyr. Methods. We used HARPS-N at the Telescopio Nazionale Gaileo and collected very high-resolution spectra (R = 115 000) of 40 red giant/red clump stars in 18 OCs (16 never or scarcely studied plus two comparison clusters). We measured their radial velocities and derived the stellar parameters (T eff , log g, v micro , and [Fe/H]) based on equivalent width measurement combined with 1D -LTE atmospherical model. Results. We discussed the relationship between metallicity and Galactocentric distance, adding literature data to our results to enlarge the sample and taking also age into account. We compared the result of observational data with that from chemo-dynamical models. These models generally reproduce the metallicity gradient well. However, at young ages we found a large dispersion in metallicity, not reproduced by models. Several possible explanations are explored, including uncertainties in the derived metallicity. We confirm the difficulties in determining parameters for young stars (age < 200 Myr), due to a combination of intrinsic factors (activity, fast rotation, magnetic fields, etc) which atmospheric models can not easily reproduce and which affect the parameters uncertainty.

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The GAPS Programme at TNG

Cited by 21 publications

References 100 publications

The Gaia-ESO Survey: a new approach to chemically characterising young open clusters

The Gaia-ESO Survey: a new approach to chemically characterising young open clusters

HADES RV programme with HARPS-N at TNG

Stellar Population Astrophysics (SPA) with TNG Atmospheric parameters of members of 16 unstudied open clusters

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