Absolute proper motion of the Galactic open cluster M 67

Bellini, Andrea; Bedin, L. R.; Pichardo, B.; Moreno, E.; Allen, Christine; Piotto, G.; Anderson, Jay

doi:10.1051/0004-6361/200913882

Cited by 58 publications

(64 citation statements)

References 30 publications

(44 reference statements)

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“…Our best estimate of the age of M67-1194 (4.2 ± 1.6 Gyr) agrees very well with determinations based on alternative methods. Most fits of isochrones to the M67 color-magnitude diagram, whether using Garching (see Magic et al 2010), Montreal (Michaud et al 2004), Padova (Yadav et al 2008), Teramo (Bellini et al 2010), Victoria (VandenBerg et al 2007), or YaleYonsei (Yadav et al) isochrones, favour an age of 4.0 ± 0.3 Gyr. Moreover, Bellini et al have recently found that the age obtained from the cluster white dwarfs is fully consistent with the aforementioned turnoff age.…”

Section: The Age Of M67mentioning

confidence: 99%

M67-1194, an unusually Sun-like solar twin in M67

Önehag

Korn

Gustafsson

et al. 2011

A&A

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Context. The rich open cluster M67 is known to have a chemical composition close to solar, and an age around 4 Gyr. It thus offers the opportunity to check our understanding of the physics and the evolution of solar-type stars in a cluster environment. Aims. We present the first spectroscopic study at high resolution, R ≈ 50 000, of the potentially best solar twin, M67-1194, identified among solar-like stars in M67. Methods. G dwarfs in M67 (d ≈ 900 pc) are relatively faint (V ≈ 15), which makes detailed spectroscopic studies time-consuming. Based on a pre-selection of solar-twin candidates performed at medium resolution by Pasquini et al. (2008, A&A, 489, 677), we explore the chemical-abundance similarities and differences between M67-1194 and the Sun, using VLT/FLAMES-UVES. Working with a solar twin in the framework of a differential analysis, we minimize systematic model errors in the abundance analysis compared to previous studies which utilized more evolved stars to determine the metallicity of M67. The differential approach yields precise and accurate chemical abundances for M67, which enhances the possibility to use this object in studies of the potential peculiarity, or normality, of the Sun. Results. We find M67-1194 to have stellar parameters indistinguishable from the solar values, with the exception of the overall metallicity which is slightly super-solar ([Fe/H] = 0.023 ± 0.015). An age determination based on evolutionary tracks yields 4.2 ± 1.6 Gyr. Most surprisingly, we find the chemical abundance pattern to closely resemble the solar one, in contrast to most known solar twins in the solar neighbourhood. Conclusions. We confirm the solar-twin nature of M67-1194, the first solar twin known to belong to a stellar association. This fact allows us to put some constraints on the physical reasons for the seemingly systematic departure of M67-1194 and the Sun from most known solar twins regarding chemical composition. We find that radiative dust cleansing by nearby luminous stars may be the explanation for the peculiar composition of both the Sun and M67-1194, but alternative explanations are also possible. The chemical similarity between the Sun and M67-1194 also suggests that the Sun once formed in a cluster like M67.

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Section: The Age Of M67mentioning

confidence: 99%

M67-1194, an unusually Sun-like solar twin in M67

Önehag

Korn

Gustafsson

et al. 2011

A&A

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“…Examples are in Carraro & Chiosi (1994), while open cluster orbits have been calculated several times in the past (see e.g. Bellini et al 2010;or Carraro et al 2006, for recent examples). However, in all past cases, no effect of the bar could be seen because of the mean large distance of the clusters from the GC and the relatively small sphere of influence of the bar.…”

Section: The Orbits Of the Inner Ocsmentioning

confidence: 99%

Open clusters towards the Galactic centre: chemistry and dynamics

Magrini

Randich

Zoccali

et al. 2010

A&A

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Context. In the framework of the study of the Galactic metallicity gradient and its time evolution, we present new high-resolution spectroscopic observations obtained with FLAMES and the fiber link to UVES at VLT of three open clusters (OCs) located within ∼7 kpc from the Galactic centre (GC): NGC 6192, NGC 6404, NGC 6583. We also present new orbit determination for all OCs with Galactocentric distances (R GC ) ≤ 8 kpc and metallicity from high-resolution spectroscopy. Aims. We aim to investigate the slope of the inner disc metallicity gradient as traced by OCs and to discuss its implication for the chemical evolution of our Galaxy. Methods. We have derived memberships of a group of evolved stars for each clusters, obtaining a sample of 4, 4, and 2 member stars in NGC 6192, NGC 6404, and NGC 6583, respectively. Using standard LTE analysis we derived stellar parameters and abundance ratios for the iron-peak elements Fe, Ni, Cr, and for the α-elements Al, Mg, Si, Ti, Ca. We calculated the orbits of the OCs currently located within 8 kpc from the GC, and discuss their implication on the present-time radial location. Results. The average metallicities of the three clusters are all oversolar: [Fe/H] = +0.12±0.04 (NGC 6192), +0.11±0.04 (NGC 6404), +0.37 ± 0.03 (NGC 6583). They are in qualitative agreement with their Galactocentric distances, because they are all internal OCs, and expected to be more metal rich than the solar neighbourhood. The abundance ratios of the other elements over iron [X/Fe] are consistent with solar values. Conclusions. The clusters we have analysed confirm, together with other OC and Cepheid data, a steep gradient in the inner disc, a signature of an evolutionary rate that is different from the one in the outer disc.

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“…Accordingly, significant efforts have recently been invested in successfully modeling the observed properties of several white dwarf populations with a high degree of realism. These include the Galactic disk and halo -see the very recent works of Cojocaru et al (2014Cojocaru et al ( , 2015 and references therein -and the system of Galactic open Article published by EDP Sciences A35, page 1 of 8 Bellini et al 2010;Bedin et al 2010) and globular clusters (Hansen et al 2002;García-Berro et al 2014;Torres et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The white dwarf population within 40 pc of the Sun

Torres

Garcı́a–Berro

2016

A&A

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Context. The white dwarf luminosity function is an important tool to understand the properties of the solar neighborhood, like its star formation history, and its age. Aims. Here we present a population synthesis study of the white dwarf population within 40 pc from the Sun, and compare the results of this study with the properties of the observed sample. Methods. We use a state-of-the-art population synthesis code based on Monte Carlo techniques, which incorporates the most recent and reliable white dwarf cooling sequences, an accurate description of the Galactic neighborhood, and a realistic treatment of all the known observational biases and selection procedures. Results. We find a good agreement between our theoretical models and the observed data. In particular, our simulations reproduce a previously unexplained feature of the bright branch of the white dwarf luminosity function, which we argue is due to a recent episode of star formation. We also derive the age of the solar neighborhood employing the position of the observed cut-off of the white dwarf luminosity function, to obtain ∼8.9 ± 0.2 Gyr. Conclusions. We conclude that a detailed description of the ensemble properties of the population of white dwarfs within 40 pc of the Sun allows us to obtain interesting constraints on the history of the Solar neighborhood.

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Absolute proper motion of the Galactic open cluster M 67

Cited by 58 publications

References 30 publications

M67-1194, an unusually Sun-like solar twin in M67

M67-1194, an unusually Sun-like solar twin in M67

Open clusters towards the Galactic centre: chemistry and dynamics

The white dwarf population within 40 pc of the Sun

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