Browsing by Author "Greco, C."

Now showing 1 - 11 of 11
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    A large and homogeneous sample of SX Phe stars in the Fornax dwarf spheroidal galaxy .
    (2006) Poretti, E.; Dell'Arciprete, L.; Clementini, G.; Held, E. V.; Greco, C.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Catelan , Marcio; Smith, H. A.; Pritzl, B.; De Lee, N.; Rest, A.
    We report on the detection of sixty-one SX Phe stars in the Fornax dwarf spheroidal galaxy using the Wide-Field Imager at the 2.2m ESO-MPI telescope. In spite of their extreme faintness (22.0...
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    On the newly discovered Canes Venatici II dSph galaxy
    (2008) Greco, C.; Catelan, Márcio
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    Stellar archaeology in the Milky Way Halo . Variable stars and stellar populations in the new Milky Way satellites discovered by the SDSS
    (2010) Musella, I.; Clementini, G.; Ripepi, V.; Dall'Ora, M.; Marconi, M.; Greco, C.; Moretti, M. I.; Kinemuchi, K.; Di Fabrizio, L.; Smith, H. A.; Kuehn, C.; Rodgers, C. T.; Beers, T. C.; Catelan, Marcio; Pritzl, B. J.
    We summarize results from the photometric survey of the recently discovered faint Milky Way satellites: Bootes I, Coma, Ursa Major II, Canes Venatici I, Canes Venatici II and Leo IV. Our team is studying these systems to characterize their stellar populations and structural parameters, as well as their variable star content, with the aim of deriving hints on the formation process of the Galactic halo....
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    Stellar populations of the newly discovered satellites of the Milky Way .
    (2008) Dall'Ora, M.; Clementini, G.; Ripepi, V.; Kinemuchi, K.; Greco, C.; Kuehn, C.; Musella, I.; Rodgers, C. T.; Di Fabrizio, L.; Beers, T. C.; Catelan, Marcio; Marconi, M.; Pritzl, B. J.; Smith., H. A.
    We have carried out an extensive observing campaign on the new dwarf spheroidal galaxies (dSphs) recently discovered by the SDSS, with the aim of characterizing their stellar populations and structural properties, as well as their variable star content. First preliminary results are presented for the Canes Venatici II, the Coma and the Ursa Major II dSphs, based on data collected at a variety of telescopes, and reaching each galaxy's Main Sequence Turn-Off (MSTO)....
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    The Fornax Project
    (2006) Clementini, G.; Greco, C.; Held, E. V.; Poretti, E.; Catelan, Marcio; Dell'Arciprete, L.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Smith, H. A.; Pritzl, B. J.; Rest, A.; De Lee, N.
    The Fornax Project aims at mapping the classical instability strip of the Fornax dwarf spheroidal galaxy, from the faint Dwarf Cepheids (V ∼ 24-25 mag) to the bright Anomalous Cepheids (V ∼ 19 mag). To achieve this goal, deep B,V time-series photometry of the galaxy has been obtained with the Wide Field Imagers (WFIs) of the ESO 2.2 m and CTIO 4 m telescopes, and the Clay camera at the Magellan 6.5 m telescope. Preliminary results are presented on the Oosterhoff classification of the RR Lyrae stars identified in a northern portion of Fornax field and in three of its globular clusters....
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    The Oosterhoff Dichotomy in the Milky Way and Other Local Group Galaxies
    (2010) Smith, Horace A.; Catelan, Marcio; Clementini, G.; Kuehn, C.; Pritzl, B.; Beers, T.; De Lee, N.; Kinemuchi, K.; Greco, C.; Ripepi, V.; Marconi, M.; Musella, I.; Moretti, M. I.; Dall'Ora, M.; Contreras, R.; Zorotovic, M.
    In 1939, P. Th. Oosterhoff investigated the properties of RR Lyrae stars in five of the globular clusters of the Milky Way. He discovered that these clusters divided into two groups, now known as Oosterhoff groups I and II, on the basis of the properties of their RR Lyrae stars. Subsequent studies of RR Lyrae variables in additional globular clusters found that most Milky Way globular clusters that contain significant numbers of RR Lyrae stars fall into one or another of the two Oosterhoff groups. Moreover, globular clusters of Oosterhoff group I tend to be more metal-rich than those of Oosterhoff group II. However, the dwarf galaxies surrounding the Milky Way, and their globular clusters, do not exhibit the Oosterhoff dichotomy. Moreover, the bulge globular clusters NGC 6388 and NGC 6441 cannot be easily assigned to one of the traditional Oosterhoff groups. We will discuss the implications of the Oosterhoff dichotomy and the Oosterhoff gap for stellar evolution and for the formation and evolution of the Galactic halo. This work has been supported in part by the National Science Foundation....
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    The Oosterhoff types of the Fornax dSph Globular Clusters
    (2006) Greco, C.; Catelan, Márcio
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    Variable stars in Fornax dwarf spheroidal galaxy
    (2005) Greco, C.; Clementini, G.; Held, E. V.; Poretti, E.; Catelan, Marcio; Dell'Arciprete, L.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Smith, H. A.; Pritzl, B. J.; Rest, A.; De Lee, N.
    We present the first results of a variable star search in the field and in the globular clusters of the Fornax dwarf spheroidal galaxy. Variable stars were identified using the Image Subtraction Technique (Alard 2000) on time-series data obtained with the ESO 2.2 m and the Magellan 6.5 m telescopes. The variable star sample includes RR Lyrae stars, Dwarf Cepheids and Anomalous Cepheids. The pulsation properties (namely: periods, light curves, period-amplitude relations and classification in Oosterhoff types) of Fornax variables from the present study are discussed in some detail....
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    Variable Stars in the Globular Clusters and in the Field of the Fornax dSph Galaxy
    (2009) Greco, C.; Clementini, G.; Held, E. V.; Poretti, E.; Catelan, Marcio; Dell'Arciprete, L.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Smith, H. A.; Pritzl, B. J.; Rest, A.; de Lee, N.
    Variable stars have been identified for the first time in Fornax 4, the globular cluster located near the center of the Fornax dwarf spheroidal galaxy. By applying the image-subtraction technique to B and V time series photometry obtained with the MagIC camera of the 6.5 m Magellan Clay telescope and with the wide field imager of the 4 m Blanco CTIO telescope, we detected 27 RR Lyrae stars (22 fundamental-mode, 3 first-overtone, and 2 double-mode pulsators) in a 2.4'×2.4' area centered on Fornax 4. The average and minimum periods of the ab-type RR Lyrae stars, =0.594 days and Pab,min=0.5191 days, respectively, as well as the revised position of the cluster in the horizontal branch type-metallicity plane, all consistently point to an Oosterhoff-intermediate status for the cluster, unlike what is seen for the vast majority of Galactic globular clusters, but in agreement with previous indications for the other globular clusters in Fornax. The average apparent magnitude of the RR Lyrae stars located within 30" from the cluster center is =21.43+/-0.03 mag (σ=0.10 mag, average of 12 stars), leading to a true distance modulus of μ0=20.64+/-0.09 mag or μ0=20.53+/-0.09 mag, depending on whether a low ([Fe/H]=-2.0) or a moderately high ([Fe/H]=-1.5) metallicity is adopted.