Zirconium, Barium, Lanthanum, and Europium Abundances in Open Clusters

Jacobson, Heather R.; Friel, Eileen D.

doi:10.1088/0004-6256/145/4/107

Cited by 73 publications

(110 citation statements)

References 54 publications

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“…While a number of OCs are consistent with the average of the stars in the disk, a significant fraction show a [La/Fe] about 0.2-0.3 dex larger than in the Sun. These departures are beyond the present error estimations, but they could be explained within the present systematic uncertanties highlighted comparing the results from different authors (e.g., Yong et al 2012;Jacobson & Friel 2013, and references therein).…”

Section: Etc) More In Generalcontrasting

confidence: 48%

“…The ages were calculated consistently, according to Carraro & Chiosi (1994). In the figures we include abundances obtained earlier (Mishenina et al 2013b(Mishenina et al , 2014 with measurements from other authors, for a number of OCs (D' Orazi et al 2009;Pancino et al 2010;Carrera & Pancino 2011;Maiorca et al 2011;D' Orazi et al 2012;Reddy et al 2012Reddy et al , 2013Bragaglia et al 2008;Yong et al 2005;Jacobson & Friel 2013) and the data for the thin disk stars were taken from the study by Mishenina et al (2013a).…”

Section: Etc) More In Generalmentioning

confidence: 99%

“…From available data, Ba overabundance seems to be present at any age and metallicity, and seems to increase at decreasing age (Maiorca et al 2011;D' Orazi et al 2012;Yong et al 2012;Jacobson & Friel 2013;Mishenina et al 2013b). The origin of this overabundance, however, is not understood, and the data analysis far from being homogeneous.…”

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confidence: 99%

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New insights on Ba overabundance in open clusters.★ Evidence for the intermediate neutron-capture process at play?

Mishenina

Pignatari

Carraro

et al. 2014

Monthly Notices of the Royal Astronomical Society

111

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Recently an increasing number of studies were devoted to measure the abundances of neutron-capture elements heavier than iron in stars belonging to Galactic Open Clusters (OCs). OCs span a sizeable range in metallicity (-0.6 ≤ [Fe/H] ≤ +0.4), and they show abundances of light elements similar to disk stars of the same age. A different pattern is observed for heavy elements. A large scatter is observed for Ba, with most OCs showing [Ba/Fe] and [Ba/La] overabundant with respect to the Sun. The origin of this overabundance is not clearly understood. With the goal of providing new observational insights we determined radial velocities, atmospheric parameters and chemical composition of 27 giant stars members of five OCs: Cr 110, Cr 261, NGC 2477, NGC 2506 and NGC 5822. We used high-resolution spectra obtained with the UVES spectrograph at ESO Paranal. We perform a detailed spectroscopic analysis of these stars to measure the abundance of up to 22 elements per star. We study the dependence of element abundance on metallicity and age with unprecedented detail, complementing our analysis with data culled from the literature. We confirm the trend of Ba overabundance in OCs, and show its large dispersion for clusters younger than ∼4 Gyr. Finally, the implications of our results for stellar nucleosynthesis are discussed. We show in this work that the Ba enrichment compared to other neutron-capture elements in OCs cannot be explained by the contributions from the slow neutroncapture process and the rapid neutron-capture process. Instead, we argue that this anomalous signature can be explained by assuming an additional contribution by the intermediate neutron-capture process.

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Section: Etc) More In Generalcontrasting

confidence: 48%

Section: Etc) More In Generalmentioning

confidence: 99%

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New insights on Ba overabundance in open clusters.★ Evidence for the intermediate neutron-capture process at play?

Mishenina

Pignatari

Carraro

et al. 2014

Monthly Notices of the Royal Astronomical Society

111

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“…Our model does not take into account the mass transfer that occurs when the planet fills its Roche lobe. This phase has been modelled by, for example Valsecchi et al (2014Valsecchi et al ( , 2015 and Jackson et al (2016), who found that its duration depends in a critical way on the interplay between the planet mass loss, which tends to increase the semi-major axis, and the stellar tides, which shrink it. We also note the above-mentioned publications concerning evaporation issues.…”

Section: A Possible Engulfment Scenario Of a Planetary Companionmentioning

confidence: 99%

A critical reassessment of the fundamental properties of GJ 504: chemical composition and age

D’Orazi

Desidera

Gratton

et al. 2017

A&A

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Context. The recent development of brand new observational techniques and theoretical models have greatly advanced the exoplanet research field. Despite significant achievements, which have allowed the detection of thousands extrasolar systems, a comprehensive understanding of planetary formation and evolution mechanisms is still desired. One relevant limitation is given by the accuracy in the measurements of planet-host star ages. The star GJ 504 has been found to host a substellar companion whose nature is strongly debated. There has been a recent difference of opinion in the literature owing to the uncertainty on the age of the system: a young age of ∼ 160 Myr would imply a giant planet as a companion, but a recent revision pointing to a solar age (∼ 4 Gyr) instead suggests a brown dwarf. Aims. With the aim of shedding light on this debated topic, we have carried out a high-resolution spectroscopic study of GJ 504 to derive stellar parameters, metallicity, and abundances of both light and heavy elements, providing a full chemical characterisation. The main objective is to infer clues on the evolutionary stage (hence the age) of this system. Methods. We performed a strictly differential (line-by-line) analysis of GJ 504 with respect to two reference stars, that is the planethost dwarf ι Hor and the subgiant HIP 84827. The former is crucial in this context because its stellar parameters (hence the evolutionary stage) is well constrained from asteroseismic observations. Regardless of the zero point offsets, our differential approach allows us to put tight constraints on the age of GJ 504 with respect to ι Hor, thereby minimising the internal uncertainties. Results. We found that the surface gravity of GJ 504 is 0.2 ± 0.07 dex lower than that of the main-sequence star ι Hor, suggesting a past turn-off evolution for our target. The isochrone comparison provides us with an age range between 1.8 and 3.5 Gyr, with a most probable age of ≈ 2.5 Gyr. Thus, our findings support an old age for the system; further evidence comes from the barium abundance, which is compatible with a solar pattern and not enhanced as observed in young stars. Conclusions. We envisaged a possible engulfment scenario to reconcile all the age indicators (spectroscopy, isochrones, rotation, and activity); this engulfment could have occurred very recently and could be responsible for the enhanced levels of rotation and chromospheric activity, as previously suggested. We tested this hypothesis, exploiting a tidal evolution code and finding that the engulfment of a hot Jupiter, with mass not larger than ≈ 3 M j and initially located at ≈ 0.03 AU, seems to be a very likely scenario.

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“…In recent years, the abundances of the s-process elements in open clusters have become a target of intense study (e.g., D 'Orazi et al 2009'Orazi et al , 2012Jacobson et al 2011;Maiorca et al 2011;Jacobson & Friel 2013;Mishenina et al 2013Mishenina et al , 2015. This (2011) have proposed a scenario with models of extra-mixing phenomena with high efficiency in the production of the neutron source 13 C in stars with Nordhaus et al 2008;Nucci & Busso 2014;Trippella et al 2014).…”

Section: Discussionmentioning

confidence: 99%

PROPERTIES OF THE OPEN CLUSTER TOMBAUGH 1 FROM HIGH-RESOLUTION SPECTROSCOPY AND uvbyCaHβ PHOTOMETRY*

Silva

Carraro²,

Anthony-Twarog

et al. 2015

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Open clusters can be the key to deepening our knowledge on various issues involving the structure and evolution of the Galactic disk and details of stellar evolution because a cluster's properties are applicable to all its members. However, the number of open clusters with detailed analysis from high-resolution spectroscopy or precision photometry imposes severe limitations on studies of these objects. To expand the number of open clusters with well-defined chemical abundances and fundamental parameters, we investigate the poorly studied, anticenter open cluster Tombaugh 1. Using precision uvbyCaHβ photometry and high-resolution spectroscopy, we derive the cluster's reddening, obtain photometric metallicity estimates, and, for the first time, present a detailed abundance analysis of 10 potential cluster stars (nine clump stars and one Cepheid). Using the radial position from the cluster center and multiple color indices, we have isolated a sample of unevolved, probable single-star members of Tombaugh 1. From 51 stars, the cluster reddening is found to be -.008, where the errors refer to the internal standard errors of the mean. The weighted photometric metallicity from m 1 and hk is [Fe/H]=−0.10±0.02, while a match to the Victoria-Regina Strömgren isochrones leads to an age of 0.95±0.10 Gyr and an apparent modulus of -m M ( )=13.10±0.10. Radial velocities identify six giants as probable cluster members, and the elemental abundances of Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Y, Ba, Ce, and Nd have been derived for both the cluster and the field stars. Tombaugh 1 appears to be a typical inner thin disk, intermediate-age open cluster of slightly subsolar metallicity, located just beyond the solar circle, with solar elemental abundance ratios except for the heavy s-process elements, which are a factor of two above solar. Its metallicity is consistent with a steep metallicity gradient in the galactocentric region between 9.5 and 12 kpc. Our study also shows that Cepheid XZ CMa is not a member of Tombaugh 1 and reveals that this Cepheid presents signs of barium enrichment, making it a probable binary star.

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Zirconium, Barium, Lanthanum, and Europium Abundances in Open Clusters

Cited by 73 publications

References 54 publications

New insights on Ba overabundance in open clusters.★ Evidence for the intermediate neutron-capture process at play?

New insights on Ba overabundance in open clusters.★ Evidence for the intermediate neutron-capture process at play?

A critical reassessment of the fundamental properties of GJ 504: chemical composition and age

PROPERTIES OF THE OPEN CLUSTER TOMBAUGH 1 FROM HIGH-RESOLUTION SPECTROSCOPY AND uvbyCaHβ PHOTOMETRY*

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