NGC 5385, NGC 2664 and Collinder 21:  Three candidate 
open cluster remnants

Villanova, S.; Carraro, G.; Marcos, R. de la Fuente; Stagni, R.

doi:10.1051/0004-6361:20041121

Cited by 12 publications

(15 citation statements)

References 21 publications

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“…The first epoch of radial velocity observations has already been described in Villanova (2003) and Villanova et al (2004b) and were carried out on the night of 2002 December 10 at the La Silla Observatory (ESO, Chile) under photometric conditions and a typical seeing of 1 arcsec. The EMMI spectrograph on the NTT 3.5-m telescope was used with a 1.0 slit to provide a spectral resolution of R = 33 000 in the wavelength range 3800−8600 Å on the two 2048 × 4096 CCDs of the mosaic detector.…”

Section: La Silla Datamentioning

confidence: 99%

“…Observationally, Bica et al (2001) selected 35 groups that stand up against the mean Galactic stellar fields, and are located relatively high onto the Galactic plane. Regrettably, close scrutiny of the kinematics in some of them (Villanova et al 2004a;Carraro et al 2005;Carraro 2006) has shown that the contrast criterion is necessary but not sufficient for detecting a remnant. In fact, when dealing with the remnant of a physical group, one expects that the remains exhibit all the features of a physical group.…”

Section: Introductionmentioning

confidence: 99%

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Observational templates of star cluster disruption

Carraro

Marcos

Villanova³

et al. 2007

A&A

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Context.Observations indicate that present-day star formation in the Milky Way disk takes place in stellar ensembles or clusters rather than in isolation. Bound, long-lived stellar groups are known as open clusters. They gradually lose stars and are severely disrupted in their final evolutionary stages, leaving an open cluster remnant made up of a few stars. Aims. In this paper, we study in detail the stellar content and kinematics of the poorly populated star cluster NGC 1901. This object appears projected against the Large Magellanic Cloud. The aim of the present work is to derive the current evolutionary status, binary fraction, age, and mass of this stellar group. These are fundamental quantities to compare with those from N-body models in order to study the most general topic of star cluster evolution and dissolution. Methods. The analysis is performed using wide-field photometry in the UBVI pass-band, proper motions from the UCAC.2 catalog, and 3 epochs of high-resolution spectroscopy, as well as results from extensive N-body calculations. Results. The star group NGC 1901 is found to be an ensemble of solar metallicity stars, 400 ± 100 Myr old, with a core radius of 0.23 pc, a tidal radius of 1.0 pc, and a location at 400 ± 50 pc from the Sun. Out of 13 confirmed members, only 5 single stars have been found. Its estimated present-day binary fraction is at least 62%. The calculated heliocentric space motion of the cluster is not compatible with possible membership in the Hyades stream. Conclusions. Our results show that NGC 1901 is a clear prototype of an open cluster remnant characterized by a high value of the binary fraction and a significant depletion of low-mass stars. In light of numerical simulations, this is compatible with NGC 1901 being what remains of a larger system initially made of 500-750 stars.

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Section: La Silla Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Observational templates of star cluster disruption

Carraro

Marcos

Villanova³

et al. 2007

A&A

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“…NGC 6994 (M73) was proved to be just a random enhancements of four bright stars by Carraro (2000) and 1 http://www.astro.yale.edu/astrom/spm3cat/spm3.html Odenchirken & Soubiran (2002). Recently, Villanova et al (2003Villanova et al ( , 2004a demonstrate that NGC 5385, NGC 2664 and Collinder 21 are as well random alignments of field stars. On the contrary, NGC 1901 was proved to be a genuine star cluster by Pavani et al (2001) and Villanova et al (2004b).…”

Section: Introductionmentioning

confidence: 99%

Probing the nature of possible open cluster remnants with the Southern Proper Motion Program

Carraro

Dinescu

Girard

et al. 2005

A&A

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Abstract.We discuss the nature of eleven Possible Open Cluster Remnants (POCRs) by using absolute proper motions from the Southern Proper Motion (SPM) Program 3 (Girard et al. 2004, AJ, 127, 3060) combined with near infrared photometry from 2MASS. The analysis is done by considering the distribution of stars in the Color-Magnitude and the Vector Point diagrams. We successfully probed the capabilities of the SPM catalog to detect a physical group by looking at the open cluster Blanco 1. However, within the uncertainties of the SPM3 catalog and basing on 2MASS photometry we conclude that only one -ESO 282SC26 -out of eleven objects turns out to be a probable physical group. We suggest it is an open cluster 1.3 Gyr old and located 1.4 kpc from the Sun.

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“…They obtained an age of 700 ± 70 Myr, d = 0.91 ± 0.08 kpc, and observed mass m obs ∼ 47 M . Villanova et al (2004) obtained CCD UBVI photometry and medium/high resolution spectroscopy for NGC 5385, NGC 2664 and Collinder 21 and their fields. The analysis using star counts, photometry, radial velocity distribution, and Tycho-2's proper motions indicated they are non physical objects.…”

Section: Introductionmentioning

confidence: 99%

Characterization of open cluster remnants

Pavani

Bica

2007

A&A

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Context. Despite progress in the theoretical knowledge of open cluster remnants and the growing search for observational identifications in recent years, open questions still remain. The methods used to analyze open cluster remnants and criteria to define them as physical systems are not homogeneous. In this work we present a systematic method for studying these objects that provides a view of their properties and allows their characterization. Aims. Eighteen remnant candidates are analyzed by means of photometric and proper motion data. These data provide information on objects and their fields. We establish criteria for characterizing open cluster remnants, taking observational uncertainties into account. Methods. 2MASS J and H photometry is employed (i) to study structural properties of the objects by means of radial stellar density profiles, (ii) to test for any similarity between objects and fields with a statistical comparison method applied to the distributions of stars in the CMDs, and (iii) to obtain ages, reddening values, and distances from the CMD, taking an index of isochrone fit into account. The UCAC2 proper motions allowed an objective comparison between objects and large solid angle offset fields.Results. The objective analysis based on the present methods indicates 13 open-cluster remnants in the sample. Evidence of the presence of binary stars is found, as expected for dynamically evolved systems. Finally, we infer possible evolutionary stages among remnants from the structure, proper motion, and CMD distributions. The low stellar statistics for individual objects is overcome by means of the construction of composite proper motion and CMD diagrams. The distributions of remnants in the composite diagrams resemble the single-star and unresolved binary star distributions of open clusters.

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NGC 5385, NGC 2664 and Collinder 21: Three candidate open cluster remnants

Cited by 12 publications

References 21 publications

Observational templates of star cluster disruption

Observational templates of star cluster disruption

Probing the nature of possible open cluster remnants with the Southern Proper Motion Program

Characterization of open cluster remnants

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