VLT observations of the peculiar globular cluster NGC 6712

Andreuzzi, G.; Marchi, Guido De; Ferraro, F. R.; Paresce, Francesco; Pulone, L.; Buonanno, R.

doi:10.1051/0004-6361:20010402

Cited by 29 publications

(29 citation statements)

References 28 publications

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“…Baumgardt & Makino (2003) showed that the presence of a tidal field throughout the evolution of a cluster results in dramatic changes in the mass function. This phenomenon was latter observed on several clusters (Andreuzzi et al 2001; De Marchi & Pulone 2007; Balbinot et al 2009) and is associated with clusters that are subject to extreme tidal interactions.…”

Section: Introductionmentioning

confidence: 71%

The tidal tails of NGC 2298

Balbinot

Santiago

Costa

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We present an implementation of the matched-filter technique to detect tidal tails of globular clusters. The method was tested using SDSS data for the globular cluster Palomar 5 revealing its well known tidal tails. We also ran a simulation of a globular cluster with a tidal tail where we successfully recover the tails for a cluster at the same position and with the same characteristics of NGC 2298. Based on the simulation we estimate that the matched-filter increases the contrast of the tail relative to the background of stars by a factor of 2.5 for the case of NGC 2298. We also present the photometry of the globular cluster NGC 2298 using the MOSAIC2 camera installed on the CTIO 4m telescope. The photometry covers ~ 3deg2 reaching V ~ 23. A fit of a King profile to the radial density profile of NGC 2298 shows that this cluster has a tidal radius of 15.91' \pm 1.07' which is twice as in the literature. The application of the matched-filter to NGC 2298 reveals several extra-tidal structures, including a leading and trailing tail. We also find that NGC 2298 has extra-tidal structures stretching towards and against the Galactic disk, suggesting strong tidal interaction. Finally, we assess how the matched-filter performs when applied to a globular cluster with and without mass segregation taken into account. We find that disregarding the effects of mass segregation may significantly reduce the detection limit of the matched-filter

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Section: Introductionmentioning

confidence: 71%

The tidal tails of NGC 2298

Balbinot

Santiago

Costa

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…The artificial stars were spatially distributed on a predefined grid such that their total number amounts to approximately 10% of the stellar objects found by DoPHOT on the initial frames. This procedure was chosen to avoid introducing artificial crowding (Andreuzzi et al 2001). …”

Section: Incompletenessmentioning

confidence: 99%

Mass Segregation in the Globular Cluster Palomar 5 and its Tidal Tails

et al. 2004

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We present the stellar main-sequence luminosity function (LF) of the disrupted, low-mass, low-concentration globular cluster Palomar 5 and its well-defined tidal tails, which emanate from the cluster as a result of its tidal interaction with the Milky Way. The results of our deep (B $ 24:5) wide-field photometry unequivocally indicate that preferentially fainter stars were removed from the cluster so that the LF of the cluster's main body exhibits a significant degree of flattening compared with other globular clusters. There is clear evidence of mass segregation, which is reflected in a radial variation of the LFs. The LF of the tidal tails is distinctly enhanced with faint, low-mass stars. Pal 5 exhibits a binary main sequence, and we estimate a photometric binary frequency of roughly 10%. The binaries also show evidence of mass segregation, with more massive binary systems being more strongly concentrated toward the cluster center.

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“…Not surprisingly, the mass function of Pal 5 is flatter than for other clusters, which reveals significant depletions of low-mass stars that were presumably stripped by the Galactic tidal field (Koch et al 2004). The globular cluster NGC 6712 is a small and sparse globular cluster whose mass function peaks at 0.75 M instead of at 0.25 M (de Marchi et al 1999;Andreuzzi et al 2001). That is, NGC 6712 is the only cluster whose mass function decreases with decreasing mass.…”

Section: Introductionmentioning

confidence: 99%

Chemical Abundances in Giant Stars of the Tidally Disrupted Globular Cluster NGC 6712 from High‐Resolution Infrared Spectroscopy

Yong

Meléndez

Cunha

et al. 2008

Astrophysical Journal

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We present abundances of C, N, O, F, Na, and Fe in six giant stars of the tidally disrupted globular cluster NGC 6712. The abundances were derived by comparing synthetic spectra with high-resolution infrared spectra obtained with the Phoenix spectrograph on the Gemini South telescope. We find large star-to-star abundance variations of the elements C, N, O, F, and Na. NGC 6712 and M4 are the only globular clusters in which F has been measured in more than two stars, and both clusters reveal F abundance variations whose amplitude is comparable to or exceeds that of O, a pattern which may be produced in M k 5 M AGB stars. Within the limited samples, the F abundance in globular clusters is lower than in field and bulge stars at the same metallicity. NGC 6712 and Pal 5 are tidally disrupted globular clusters whose red giant members exhibit O and Na abundance variations not seen in comparable metallicity field stars. Therefore, globular clusters such as NGC 6712 and Pal 5 cannot contribute many field stars and/or field stars do not form in environments with chemical enrichment histories like those of NGC 6712 and Pal 5. Although our sample size is small, from the amplitude of the O and Na abundance variations we infer a large initial cluster mass and tentatively confirm that NGC 6712 was once one of the most massive globular clusters in our Galaxy.

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VLT observations of the peculiar globular cluster NGC 6712

Cited by 29 publications

References 28 publications

The tidal tails of NGC 2298

The tidal tails of NGC 2298

Mass Segregation in the Globular Cluster Palomar 5 and its Tidal Tails

Chemical Abundances in Giant Stars of the Tidally Disrupted Globular Cluster NGC 6712 from High‐Resolution Infrared Spectroscopy

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