The star cluster age function in the Galactic disc with <i>Gaia</i> DR2

Anders, F.; Cantat-Gaudin, T.; Quadrino-Lodoso, Irene; Gieles, M.; Jordi, C.; Castro-Ginard, A.; Balaguer-Núñez, L.

doi:10.1051/0004-6361/202038532

Cited by 32 publications

(17 citation statements)

References 44 publications

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“…This may be due to the combination of i) the approach adopted in OCfinder, where we are limited to the most compact object in the search region (see Sect. 3.2), and those are more likely to be already known at these close distances; and ii) we expanded the search to G = 18 mag, which naturally pushes the search to farther distances (see Anders et al 2021, to see the performance of OCfinder in terms of complete-ness for nearby objects), together with the above consideration of a better completeness of the nearby population.…”

Section: Notesmentioning

confidence: 99%

Hunting for open clusters in Gaia DR2: 582 new open clusters in the Galactic disc

Castro-Ginard

Jordi

Luri

et al. 2020

A&A

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Context. Open clusters are key targets for both Galaxy structure and evolution and stellar physics studies. Since Gaia DR2 publication, the discovery of undetected clusters has proven that our samples were not complete. Aims. Our aim is to exploit the Big Data capabilities of machine learning to detect new open clusters in Gaia DR2, and to complete the open cluster sample to enable further studies on the Galactic disc. Methods. We use a machine learning based methodology to systematically search in the Galactic disc, looking for overdensities in the astrometric space and identifying them as open clusters using photometric information. First, we use an unsupervised clustering algorithm, DBSCAN, to blindly search for these overdensities in Gaia DR2 (l, b, , µ α * , µ δ ). After that, we use a deep learning artificial neural network trained on colour-magnitude diagrams to identify isochrone patterns in these overdensities, and to confirm them as open clusters. Results. We find 582 new open clusters distributed along the Galactic disc, in the region |b| < 20 • . We can detect substructure in complex regions, and identify the tidal tails of a disrupting cluster UBC 274 of ∼ 3 Gyr located at ∼ 2 kpc. Conclusions. Adapting the methodology into a Big Data environment allows us to target the search driven by physical properties of the open clusters, instead of being driven by its computational requirements. This blind search for open clusters in the Galactic disc increases in a 45% the number of known open clusters.

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Section: Notesmentioning

confidence: 99%

Hunting for open clusters in Gaia DR2: 582 new open clusters in the Galactic disc

Castro-Ginard

Jordi

Luri

et al. 2020

A&A

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199

177

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“…Magrini et al 2017Magrini et al , 2018Donor et al 2020), the Milky Way structure (e.g. Meingast et al 2019;Castro-Ginard et al 2020;Anders et al 2020) and the cluster formation and disruption processes (e.g. Sacco et al 2017b;Bravi et al 2018;Piatti et al 2019).…”

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confidence: 99%

Stellar Population Astrophysics (SPA) with TNG

Casali

Magrini

Frasca

et al. 2020

A&A

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Context. Open clusters are excellent tracers of the chemical evolution of the Galactic disc. The spatial distribution of their elemental abundances, through the analysis of high-quality and high-resolution spectra, provides insight into the chemical evolution and mechanisms of element nucleosynthesis in regions characterised by different conditions (e.g. star formation efficiency and metallicity). Aims. In the framework of the Stellar Population Astrophysics (SPA) project, we present new observations and spectral analysis of four sparsely studied open clusters located in the solar neighbourhood, namely Collinder 350, Gulliver 51, NGC 7044, and Ruprecht 171. Methods. We exploit the HARPS-N spectrograph at the TNG telescope to acquire high-resolution optical spectra for 15 member stars of four clusters. We derive stellar parameters (Teff, log g, [Fe/H] and ξ) using both the equivalent width (EW) analysis and the spectral fitting technique. We compute elemental abundances for light, α-, iron-peak, and n-capture elements using the EW measurement approach. We investigate the origin of the correlation between metallicity and stellar parameters derived with the EW method for the coolest stars of the sample (Teff < 4300 K). The correlation is likely due to the challenging continuum setting and to a general inaccuracy of model atmospheres used to reproduce the conditions of very cool giant stars. Results. We locate the properties of our clusters in the radial distributions of metallicity and abundance ratios, comparing our results with clusters from the Gaia-ESO and APOGEE surveys. We present the [X/Fe]−[Fe/H] and [X/Fe]−RGC trends for elements in common between the two surveys. Finally, we derive the C and Li abundances as a function of the evolutionary phase and compare them with theoretical models. Conclusions. The SPA survey, with its high-resolution spectra, allows us to fully characterise the chemistry of nearby clusters. With a single set of spectra, we provide chemical abundances for a variety of chemical elements, which are comparable to those obtained in two of the largest surveys combined. The metallicities and abundance ratios of our clusters fit very well in the radial distributions defined by the recent literature, reinforcing the importance of star clusters to outline the spatial distribution of abundances in our Galaxy. Moreover, the abundances of C and Li, modified by stellar evolution during the giant phase, agree with evolutionary prescriptions (rotation-induced mixing) for their masses and metallicities.

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“…Young distant objects are more obscured and are generally little known, the catalogue by Cantat-Gaudin et al ( 2020) only includes 24 objects younger than 1 Gyr with a distance of R GC > 13 kpc. In the solar neighbourhood, however, the age distribution shows that the younger ones represent the by far most frequent population (Anders et al 2021).…”

Section: Summary and Concluding Remarksmentioning

confidence: 98%

The Galactic metallicity gradient shown by open clusters in the light of radial migration

Netopil,

Oralhan,

Çakmak

et al. 2021

Preprint

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During the last years and decades several individual studies and large-scale spectroscopic surveys significantly improved our knowledge of the Galactic metallicity distribution based on open clusters. The availability of Gaia data provided a further step forward in our knowledge. However, still some open issues remain, for example the influence of radial migration on the interpretation of the observed gradients. We used spectroscopic metallicities from individual studies and from the APOGEE survey to compile a sample of 136 open clusters, with a membership verification based on Gaia DR2. Additionally, we present photometric metallicity estimates of 14 open clusters in a somewhat outer Galactic region. Eight age groups allow us to study the evolution of the metallicity gradient in detail, showing within the errors an almost constant gradient of about −0.06 dex/kpc. Furthermore, using the derived gradients and an analysis of the individual objects, we estimate a mean migration rate of 1 kpc/Gyr for objects up to about 2 Gyr. Here, the change of the guiding radius is clearly the main contributor. For older and dynamically hotter objects up to 6 Gyr we infer a lower migration rate of up to 0.5 kpc/Gyr. The influence of epicyclic excursions increases with age and contributes already about 1 kpc to the total migration distance after 6 Gyr. A comparison of our results with available models shows good agreement. However, there is still a lack of a suitable coverage of older objects, future studies are still needed to provide a better sampling in this respect.

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The star cluster age function in the Galactic disc with Gaia DR2

Cited by 32 publications

References 44 publications

Hunting for open clusters in Gaia DR2: 582 new open clusters in the Galactic disc

Hunting for open clusters in Gaia DR2: 582 new open clusters in the Galactic disc

Stellar Population Astrophysics (SPA) with TNG

The Galactic metallicity gradient shown by open clusters in the light of radial migration

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