ORCID Profile
0000-0002-4609-3463
Current Organisation
INAF-Osservatorio Astronomico di Padova
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Publisher: Oxford University Press (OUP)
Date: 24-09-2011
Publisher: Cambridge University Press (CUP)
Date: 08-2010
DOI: 10.1017/S1743921310003200
Abstract: We present the first results of a comprehensive HST study of the star-formation history of Fornax dSph, based on WFPC2 imaging of 7 Fornax fields. Our observations reach the oldest main-sequence turnoffs, allowing us to address fundamental questions of dwarf galaxy evolution, such as the spatial variations in the stellar content, and whether the old stellar population is made up of stars formed in a very early burst or the result of a more continuous star formation.
Publisher: American Astronomical Society
Date: 21-10-2009
Publisher: American Astronomical Society
Date: 22-12-2016
Publisher: Oxford University Press (OUP)
Date: 03-2009
Publisher: American Astronomical Society
Date: 07-1995
DOI: 10.1086/117507
Publisher: EDP Sciences
Date: 10-12-2015
Publisher: Oxford University Press (OUP)
Date: 05-2006
Publisher: EDP Sciences
Date: 06-2019
DOI: 10.1051/0004-6361/201834636
Abstract: Context . Pismis 18 is a moderately populated, intermediate-age open cluster located within the solar circle at a Galactocentric distance of about seven kpc. Few open clusters have been studied in detail in the inner disc region before the Gaia -ESO Survey. Aims . New data from the Gaia -ESO Survey allowed us to conduct an extended radial velocity membership study as well as spectroscopic metallicity and detailed chemical abundance measurements for this cluster. Methods . Gaia -ESO Survey data for 142 potential members, lying on the upper main sequence and on the red clump, yielded radial velocity measurements, which, together with proper motion measurements from the Gaia Second Data Release ( Gaia DR2), were used to determine the systemic velocity of the cluster and membership of in idual stars. Photometry from Gaia DR2 was used to re-determine cluster parameters based on high confidence member stars only. Cluster abundance measurements of six radial-velocity member stars with UVES high-resolution spectroscopy are presented for 23 elements. Results . The average radial velocity of 26 high confidence members is −27.5 ± 2.5 (std) km s −1 with an average proper motion of pmra = −5.65 ± 0.08 (std) mas yr −1 and pmdec = −2.29 ± 0.11 (std) mas yr −1 . According to the new estimates, based on high confidence members, Pismis 18 has an age of τ = 700 +40 −50 Myr, interstellar reddening of E ( B − V ) = 0.562 +0.012 −0.026 mag and a de-reddened distance modulus of DM 0 = 11.96 +0.10 −0.24 mag. The median metallicity of the cluster (using the six UVES stars) is [Fe/H] = +0.23 ± 0.05 dex, with [ α /Fe] = 0.07 ± 0.13 and a slight enhancement of s - and r -neutron-capture elements. Conclusions . With the present work, we fully characterized the open cluster Pismis 18. We confirmed its present location in the inner disc. We estimated a younger age than the previous literature values and we gave, for the first time, its metallicity and its detailed abundances. Its [ α /Fe] and [ s -process/Fe], both slightly super-solar, are in agreement with other inner-disc open clusters observed by the Gaia -ESO survey.
Publisher: Wiley
Date: 04-11-2009
Abstract: Using deep HST/ACS observations of the core of the Perseus Cluster, we identify a large population of dwarf elliptical galaxies down to MV = –12. All these dwarfs are remarkably smooth in appearance, showing no evidence for internal features that could be the result of tidal processes or star formation induced by the cluster potential. Based on these observations and the relatively large sizes of these dwarfs, we argue that at least some must have a large dark matter component to prevent their disruption by the cluster potential. We further derive a new method to quantify the dark matter content of cluster dSphs without the use of kinematics, which are impossible to obtain at these distances. We find that mass‐to‐light ratios for dwarfs in the core of the Perseus Cluster are comparable to those found for Local Group dSphs, ranging between M ⊙ / L ⊙ ≈ 1 and 120. This is evidence that dwarf spheroidals reside in dark matter subhalos that protect them from tidal processes in the cores of dense clusters (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Publisher: Oxford University Press (OUP)
Date: 03-2009
Publisher: Oxford University Press (OUP)
Date: 28-01-2014
Publisher: EDP Sciences
Date: 28-04-2016
Publisher: EDP Sciences
Date: 20-03-2012
Location: South Africa
No related grants have been discovered for Enrico Valerio Held.