Browsing by Author "De Propris, R."

Now showing 1 - 4 of 4
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    Constraints on the formation of the globular cluster IC 4499 from multiwavelength photometry
    (2011) Walker, A. R.; Kunder, A. M.; Andreuzzi, G.; Di Cecco, A.; Stetson, P. B.; Monelli, M.; Cassisi, S.; Bono, G.; De Propris, R.; Dall'Ora, M.; Nemec, J. M.; Zoccali, M.
    We present new multiband photometry for the Galactic globular cluster IC 4499 extending well past the main-sequence turn-off in the U, B, V, R, I and DDO51 bands. This photometry is used to determine that IC 4499 has an age of 12 +/- 1 Gyr and a cluster reddening of E(B - V) = 0.22 +/- 0.02. Hence, IC 4499 is coeval with the majority of Galactic globular clusters, in contrast to suggestions of a younger age. The density profile of the cluster is observed to not flatten out to at least r similar to 800 arcsec, implying that either the tidal radius of this cluster is larger than previously estimated, or that IC 4499 is surrounded by a halo. Unlike the situation in some other, more massive, globular clusters, no anomalous colour spreads in the ultraviolet are detected among the red giant branch stars. The small uncertainties in our photometry should allow the detection of such signatures apparently associated with variations of light elements within the cluster, suggesting that IC 4499 consists of a single stellar population.
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    G2C2-I. Homogeneous photometry for Galactic globular clusters in SDSS passbands
    (2014) Vanderbeke, J.; West, M.; De Propris, R.; Peng, E.; Blakeslee, J.; Jordán Colzani, Andrés Cristóbal; Coté, P.; Gregg, M.; Ferrarese, L.; Takamiya, M.; Baes, M.
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    G2C2-II. Integrated colour-metallicity relations for Galactic globular clusters in SDSS passbands
    (2014) Vanderbeke, J.; West, M.; De Propris, R.; Peng, E.; Blakeslee, J.; Jordán Colzani, Andrés Cristóbal; Cote, P.; Gregg, M.; Ferrarese, L.; Takamiya, M.; Baes, M.
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    Scaling relations of the colour-detected cluster RzCS 052 at z=1.016 and some other high-redshift clusters
    (2008) Andreon, S.; De Propris, R.; Puddu, E.; Giordano, L.; Quintana, H.
    We report on the discovery of the z = 1.016 cluster RzCS 052 using a modified red-sequence method, follow up spectroscopy and X-ray imaging. This cluster has a velocity dispersion of 710 +/- 150 km s(-1), a virial mass of 4.0 x 10(14) M-circle dot (based on 21 spectroscopically confirmed members) and an X-ray luminosity of (0.68 +/- 0.47) x 10(44) erg s(-1) in the [1-4] keV band. This optically selected cluster appears to be of richness class 3 and to follow the known L-X-sigma(v) relation for high-redshift X-ray selected clusters. Using these data, we find that the halo occupation number for this cluster is only marginally consistent with what was expected assuming a self-similar evolution of cluster scaling relations, suggesting perhaps a break of them at z similar to 1. We also rule out a strong galaxy merging activity between z = 1 and today. Finally, we present a Bayesian approach to measuring cluster velocity dispersions and X-ray luminosities in the presence of a background: we critically reanalyse recent claims for X-ray underluminous clusters using these techniques and find that the clusters can be accommodated within the existing L-X-sigma(v) relation.