The surface brightness profile of the remote cluster NGC 2419

Bellazzini, M.

doi:10.1051/0004-6361:20078130

Cited by 36 publications

(60 citation statements)

References 24 publications

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“…NGC 2419 resides at 90 kpc from the center of our Galaxy, has a half-mass and tidal radius of 20 pc and 230 pc, respectively, and a V −band luminosity of 5 × 10 5 L ⊙ (Harris 1996), which implies a total stellar mass of ≈ 10 6 M ⊙ . Bellazzini (2007) recently measured the stellar surface density of NGC 2419 to 200 pc. The core and half-mass relaxation times of this GC are 9 and 35 Gyr, respectively.…”

Section: Resultsmentioning

confidence: 99%

Evidence Against Dark Matter Halos Surrounding the Globular Clusters Mgc1 and NGC 2419

Conroy

Loeb

Spergel

2011

ApJ

107

102

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The conjecture that the ancient globular clusters (GCs) formed at the center of their own dark matter halos was first proposed by Peebles (1984), and has recently been revived to explain the puzzling abundance patterns observed within many GCs. In this paper we demonstrate that the outer stellar density profile of isolated GCs is very sensitive to the presence of an extended dark halo. The GCs NGC 2419, located at 90 kpc from the center of our Galaxy, and MGC1, located at ∼ 200 kpc from the center of M31, are ideal laboratories for testing the scenario that GCs formed at the centers of massive dark halos. Comparing analytic models to observations of these GCs, we conclude that these GCs cannot be embedded within dark halos with a virial mass greater than 10 6 M ⊙ , or, equivalently, the dark matter halo mass-to-stellar mass ratio must be M DM /M * < 1. If these GCs have indeed orbited within weak tidal fields throughout their lifetimes, then these limits imply that these GCs did not form within their own dark halos. Recent observations of an extended stellar halo in the GC NGC 1851 are also interpreted in the context of our analytic models. Implications of these results for the formation of GCs are briefly discussed.

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Section: Resultsmentioning

confidence: 99%

Evidence Against Dark Matter Halos Surrounding the Globular Clusters Mgc1 and NGC 2419

Conroy

Loeb

Spergel

2011

ApJ

107

102

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“…Previous studies of its surface brightness profile revealed some evidence for extratidal stars (Bellazzini 2007) and references therein). In Fig.…”

Section: Ngc 2419mentioning

confidence: 95%

Search for extratidal features around 17 globular clusters in the Sloan Digital Sky Survey

Jordi

Grebel

2010

A&A

110

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Context. The dynamical evolution of a single globular cluster and also of the entire Galactic globular cluster system has been studied theoretically in detail. In particular, simulations show how the "lost" stars are distributed in tidal tails emerging from the clusters. Aims. We investigate the distribution of Galactic globular cluster stars on the sky to identify such features as tidal tails. The Sloan Digital Sky Survey provides consistent photometry of a large part of the sky to study the projected two-dimensional structure of the 17 globular clusters in its survey area. Methods. We used a color-magnitude weighted counting algorithm to map (potential) cluster member stars on the sky. Results. We recover the already known tidal tails of Pal 5 and NGC 5466. For NGC 4147 we find a two-arm morphology. Possible indications of tidal tails are also seen around NGC 5053 and NGC 7078, confirming earlier suggestions. Moreover, we find potential tails around NGC 5904 and Pal 14. Especially for Palomar clusters other than Pal 5, deeper data are needed to confirm or to rule out the existence of tails. For many of the remaining clusters in our sample we observe a pronounced extratidal halo, which is particularly large for NGC 7006 and Pal 1. In some cases, the extratidal halos may be associated with the stream of the Sagittarius dwarf spheroidal galaxy (e.g., NGC 4147, NGC 5024, NGC 5053).

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“…Equations (5) and (6) have been derived by us from secondary standard stars in NGC 2419 (Bellazzini 2007). We interpolated the Schlegel et al (1998) reddening maps to obtain an estimate of E(B − V) for each source included in our final f1 and f2 catalogues.…”

Section: Astrometry Photometric Calibration and Reddeningmentioning

confidence: 99%

An optical and H i study of the dwarf Local Group galaxy VV124 = UGC4879

Bellazzini

Beccari

Oosterloo

et al. 2011

A&A

Self Cite

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We present a detailed study of the dwarf galaxy VV124 (UGC4879), recently recognized as a remarkably isolated member of the Local Group. We have obtained deep (r 26.5) wide-field (23 × 23 ) g,r photometry of individual stars with the LBC camera at the Large Binocular Telescope under sub-arcsec seeing conditions. The color-magnitude diagram suggests that the stellar content of the galaxy is dominated by an old, metal-poor population, with a significant metallicity spread. A very clean detection of the RGB tip allows us to derive an accurate distance of D = 1.3 ± 0.1 Mpc. Combining surface photometry with star counts, we are able to trace the surface brightness profile of VV124 out to ∼5 1.9 kpc radius (where μ r 30 mag/arcsec 2 ), showing that it is much more extended than previously believed. Moreover, the surface density map reveals the presence of two symmetric flattened wings emanating from the central elongated spheroid and aligned with its major axis, resembling a stellar disk seen nearly edge-on. We also present H i observations obtained with the Westerbork Synthesis Radio Telescope (WSRT), the first ever of this object. A total amount of 10 6 M of H i gas is detected in VV124. Compared to the total luminosity, this gives a value of M HI /L V = 0.11, which is particularly low for isolated Local Group dwarfs. The spatial distribution of the gas does not correlate with the observed stellar wings. The systemic velocity of the H i in the region superposed to the stellar main body of the galaxy is V h = −25 km s −1 . The velocity field shows substructures typical of galaxies of this size but no sign of rotation. The H i spectra indicates the presence of a two-phase interstellar medium, again typical of many dwarf galaxies.

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The surface brightness profile of the remote cluster NGC 2419

Cited by 36 publications

References 24 publications

Evidence Against Dark Matter Halos Surrounding the Globular Clusters Mgc1 and NGC 2419

Evidence Against Dark Matter Halos Surrounding the Globular Clusters Mgc1 and NGC 2419

Search for extratidal features around 17 globular clusters in the Sloan Digital Sky Survey

An optical and H i study of the dwarf Local Group galaxy VV124 = UGC4879

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