Rome, Italy
Rome, Italy
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Di Cecco A.,ESO | Bono G.,UniToV | Monelli M.,IAC | Stetson P.B.,National Research Council Canada | And 4 more authors.
Astrophysics and Space Science Proceedings | Year: 2012

We present the preliminary results of the ground-based (MegaCam@CFHT) and space-based (ACS@HST) photometry for the Galactic globular cluster M71. By comparing data and theory, we found that the age (11.0±1.5Gyr) of M71 agrees well with the bulk of the more metal poor globular clusters. © Springer-Verlag Berlin Heidelberg 2012.

Bono G.,UniToV | Bono G.,National institute for astrophysics | Stetson P.B.,National Research Council Canada | Vandenberg D.A.,UVIC | And 28 more authors.
Astrophysical Journal Letters | Year: 2010

We present a new method to estimate the absolute ages of stellar systems. This method is based on the difference in magnitude between the main-sequence turnoff (MSTO) and a well-defined knee located along the lower main sequence (MSK). This feature is caused by the collisionally induced absorption of molecular hydrogen, and it can easily be identified in near-infrared (NIR) and in optical-NIR color-magnitude diagrams of stellar systems. We took advantage of deep and accurate NIR images collected with the Multi-Conjugate Adaptive Optics Demonstrator temporarily available on the Very Large Telescope and of optical images collected with the Advanced Camera for Surveys Wide Field Camera on the Hubble Space Telescope and with ground-based telescopes to estimate the absolute age of the globular NGC 3201 using both the MSTO and the Δ(MSTO-MSK). We have adopted a new set of cluster isochrones, and we found that the absolute ages based on the two methods agree to within 1σ. However, the errors of the ages based on the Δ(MSTO-MSK) method are potentially more than a factor of 2 smaller, since they are not affected by uncertainties in cluster distance or reddening. Current isochrones appear to predict slightly bluer (≈0.05 mag) NIR and optical-NIR colors than observed for magnitudes fainter than the MSK. © 2010. The American Astronomical Society. All rights reserved..

Coppola G.,National institute for astrophysics | Dall'ora M.,National institute for astrophysics | Marconi M.,National institute for astrophysics | Musella I.,National institute for astrophysics | And 7 more authors.
Memorie della Societa Astronomica Italiana - Journal of the Italian Astronomical Society | Year: 2012

We present a preliminary analysis of our deep Near-Infrared (NIR) photometry of the Galactic Globular Cluster NGC5904(M5), based on data collected with SOFI at New Technology Telescope (NTT) (ESO, La Silla) and NICS at Telescopio Nazionale Galileo (TNG). Data cover a significant fraction of the cluster and the Color Magnitude Diagram (CMD) ranges from the Tip of the Red Giant Branch down to the Main Sequence Turn-Off region. By using the K-band Period-Luminosity-Metallicity relation (PLZK) of RR Lyrae stars, we supply a new estimate of NGC5904 distance, i.e. (m - M)0 = 14.39 ± 0.10. © SAIt 2012.

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