Metal Abundances in Extremely Distant Galactic Old Open Clusters. II. Berkeley 22 and Berkeley 66

Villanova, S.; Carraro, G.; Bresolin, Fabio; Patat, F.

doi:10.1086/430958

Cited by 29 publications

(26 citation statements)

References 17 publications

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“…If we include the two new clusters Berkeley 75 and Berkeley 25, Berkeley 22 and Berkeley 66 (around 3-4 Gyr old, Villanova et al 2005) and Berkeley 29 (4 Gyr, Carraro et al 2004), for which we report new estimates of the age, the dip that Ortolani et al (2005) report in the old open clusters age distribution (their Fig. 11) becomes less prominent, and the reality of a peak at 5 Gyr less significant.…”

Section: Discussionmentioning

confidence: 84%

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A photometric study of the old open clusters Berkeley 73, Berkeley 75 and Berkeley 25

Carraro

Geisler

Moitinho³

et al. 2005

A&A

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CCD BVI photometry of the faint open clusters Berkeley 73, Berkeley 75 and Berkeley 25 are presented. The two latter are previously unstudied clusters to our knowledge. While Berkeley 73 is found to be of intermediate-age (about 1.5 Gyr old), Berkeley 75 and Berkeley 25 are old clusters, with ages greater than 3.0 Gyr. We provide also estimates of the clusters size. All these clusters lie far away from the Galactic Center, at R GC ≥ 16 kpc, and quite high on the Galactic plane, at |Z | ≥ 1.5 kpc. They are therefore important targets to probe the properties of the structure of the Galaxy in this direction, where the Canis Major over-density has been discovered to be located.

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Section: Discussionmentioning

confidence: 84%

“…We only known a few clusters located so distant from the center of the Galaxy (Villanova et al 2005), and therefore they are crucial targets for spectroscopic follow-up. Also, Berkeley 25 is one of the old open clusters located at the highest Galactic latitude (see Table 4; and Friel 1995).…”

Section: Cluster Fundamental Parametersmentioning

confidence: 99%

A photometric study of the old open clusters Berkeley 73, Berkeley 75 and Berkeley 25

Carraro

Geisler

Moitinho³

et al. 2005

A&A

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“…This is a distant open cluster, located well beyond the Perseus arm, but very close to the plane, and very reddened for that reason (Phelps & Janes 1996;Guarnieri & Carraro 1997;Villanova et al 2005). It represents an interesting case since it lies along the line of sight where Xu et al (2006) estimate the distance to the Perseus arm to be about 2 kpc.…”

Section: Berkeley 66mentioning

confidence: 91%

Blue straggler stars in Galactic open clusters and the effect of field star contamination

Carraro¹,

Vazquez

Moitinho

2008

A&A

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Context. We investigate the distribution of blue straggler stars in the field of three open star clusters. Aims. The main purpose is to highlight the crucial role played by general Galactic disk fore-/back-ground field stars, which are often located in the same region of the color magnitude diagram as blue straggler stars. Methods. We analyze photometry taken from the literature of 3 open clusters of intermediate/old age rich in blue straggler stars, which are projected in the direction of the Perseus arm, and study their spatial distribution and the color magnitude diagram. Results. As expected, we find that a large portion of the blue straggler population in these clusters are simply young field stars belonging to the spiral arm. This result has important consequences on the theories of the formation and statistics of blue straggler stars in different population environments: open clusters, globular clusters, or dwarf galaxies. Conclusions. As previously emphasized by many authors, a detailed membership analysis is mandatory before comparing the blue straggler population in star clusters to theoretical models. Moreover, these sequences of young field stars (blue plumes) are potentially powerful tracers of Galactic structure and they require further consideration.

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“…These clusters are: Berkeley 29 and Saurer 1 (Carraro et al 2004), Berkeley 22 (Villanova et al 2005), Tombaugh 2 (Frinchaboy et al 2007), Berkeley 21 (Hill & Pasquini 1999;Yong et al 2005), and Berkeley 20, Berkeley 31, and NGC 2141 from Yong et al (2005). These additional clusters are all located in the Third Galactic Quadrant, having 187…”

Section: Extension Of the Cluster Samplementioning

confidence: 95%

Old open clusters in the outer Galactic disk

Carraro

Geisler

Villanova

et al. 2007

A&A

121

159

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Context. The outer parts of the Milky Way disk are believed to be one of the main arenas where the accretion of external material in the form of dwarf galaxies and subsequent formation of streams is taking place. The Monoceros stream and the Canis Major and Argo over-densities are notorious examples. Understanding whether what we detect is the signature of accretion or, more conservatively, simply the intrinsic nature of the disk, represents one of the major goals of modern Galactic astronomy. Aims. We try to shed more light on the properties of the outer disk by exploring the properties of distant anti-center old open clusters. We want to verify whether distant clusters follow the chemical and dynamical behavior of the solar vicinity disk, or whether their properties can be better explained in terms of an extra-galactic population. Methods. VLT high resolution spectra have been acquired for five distant open clusters: Ruprecht 4, Ruprecht 7, Berkeley 25, Berkeley 73 and Berkeley 75. We derive accurate radial velocities to distinguish field interlopers and cluster members. For the latter we perform a detailed abundance analysis and derive the iron abundance [Fe/H] and the abundance ratios of several α elements. Results. Our analysis confirms previous indications that the radial abundance gradient in the outer Galactic disk does not follow the expectations extrapolated from the solar vicinity, but exhibits a shallower slope. By combining the metallicity of the five program clusters with eight more clusters for which high resolution spectroscopy is available, we find that the mean metallicity in the outer disk between 12 and 21 kpc from the Galactic center is [Fe/H] ≈ −0.35, with only marginal indications for a radial variation. In addition, all the program clusters exhibit solar scaled or slightly enhanced α elements, similar to open clusters in the solar vicinity and thin disk stars. Conclusions. We investigate whether this outer disk cluster sample might belong to an extra-galactic population, like the Monoceros ring. However, close scrutiny of their properties -location, kinematics and chemistry -does not convincingly favor this hypothesis. On the contrary, they appear more likely genuine Galactic disk clusters. We finally stress the importance to obtain proper motion measurements for these clusters to constrain their orbits.

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Metal Abundances in Extremely Distant Galactic Old Open Clusters. II. Berkeley 22 and Berkeley 66

Cited by 29 publications

References 17 publications

A photometric study of the old open clusters Berkeley 73, Berkeley 75 and Berkeley 25

A photometric study of the old open clusters Berkeley 73, Berkeley 75 and Berkeley 25

Blue straggler stars in Galactic open clusters and the effect of field star contamination

Old open clusters in the outer Galactic disk

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