M. Castellani
A5079088974- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Scientific Research and Discoveries
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
- Adaptive optics and wavefront sensing
- Atmospheric Ozone and Climate
- History and Developments in Astronomy
- Water Systems and Optimization
- Diverse academic and cultural studies
- Geophysical Methods and Applications
- Underwater Acoustics Research
- Cosmology and Gravitation Theories
- CCD and CMOS Imaging Sensors
- Impact of Light on Environment and Health
- Pulsars and Gravitational Waves Research
- Magnetic Properties and Applications
- Web Applications and Data Management
- Remote Sensing in Agriculture
- Cognitive and psychological constructs research
University of Birmingham
2022-2024
Beihang University
2024
Cardiff University
2024
University of Portsmouth
2024
Astronomical Observatory of Rome
2009-2023
National Institute for Astrophysics
2006-2022
University of Brescia
2020
University of Milan
2020
Atotech (Germany)
2018
Max Planck Society
2018
Aims. We describe the photometric content of second data release Gaia project (Gaia DR2) and its validation along with quality data. Methods. The was mainly carried out using an internal analysis photometry. External comparisons were also made, but limited by precision systematics that may be present in external catalogues used. Results. In addition to assessment, we best estimates three passbands. Various colour-colour transformations are derived enable users convert between commonly used...
Gaia Early Data Release 3 contains astrometry and photometry results for about 1.8 billion sources based on observations collected by the ESA satellite during first 34 months of operations. This paper focuses photometric content, describing input data, algorithms, processing, validation results. Particular attention is given to quality data a number features that users may need take into account make best use EDR3 catalogue. The treatment BP RP background has been updated include better...
We present new nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio and broad range in metal abundances (Z=0.0001--0.02). The stellar masses luminosities adopted to construct the pulsation were fixed according detailed central He burning Horizontal Branch evolutionary models. cover luminosity effective temperatures modal stability is investigated for both fundamental first overtones. predict topology...
(Abridged) Blue (BP) and Red (RP) Photometer low-resolution spectral data is one of the exciting new products in Gaia Data Release 3 (Gaia DR3). We calibrate about 65 billion individual transit spectra onto same mean BP/RP instrument through a series calibration steps, including background subtraction, CCD geometry an iterative procedure for efficiency as well variations line-spread function dispersion across focal plane time. The calibrated are then combined each source terms expansion into...
Context. Gaia Data Release 3 contains astrometry and photometry results for about 1.8 billion sources based on observations collected by the European Space Agency (ESA) satellite during first 34 months of its operational phase (the same period covered early 3; EDR3). Low-resolution spectra 220 million are one important new data products included in this release. Aims. In paper, we focus external calibration low-resolution spectroscopic content, describing input data, algorithms, processing,...
view Abstract Citations (170) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mass Loss in Globular Cluster Red Giants: an Evolutionary Investigation Castellani, M. ; V. The evolution of Population II red giants has been studied adopting Reimer's formalism for the efficiency mass loss. computations a model 0.8 solar mass, Y = 0.23, Z 0.0002 are presented selected assumptions on value parameter eta governing mass-loss rate. Comparison with...
In this paper we present multiband optical and UV Hubble Space Telescope photometry of the two Galactic globular clusters NGC 6388 6441. We have obtained first color-magnitude diagrams for These confirm previous results, in bands, about presence a sizeable stellar population extremely hot horizontal branch stars. At least 6388, find clear indication that at end distribution stars forms hook-like feature, closely resembling those observed 2808 Omega Centauri. briefly review theoretical...
Context. This paper presents an overview of the photometric data that are part first Gaia release. Aims. The principles processing and main characteristics presented. Methods. calibration strategy is outlined briefly properties resulting photometry Results. Relations with other broadband systems provided. overall precision for shown to be at milli-magnitude level has a clear potential improve further in future releases.
Using observations from the Hubble Space Telescope archive, color-magnitude diagrams (CMDs) have been constructed for globular cluster 4 in Fornax dwarf spheroidal galaxy and its surrounding field. These extend below main-sequence turnoffs yielded measurements of ages populations. The most prominent features CMD field population are a heavily populated red clump horizontal-branch (HB) stars, broad giant branch (RGB), main sequence that spans large range luminosity. In this CMD, there very...
We present a new complete Near-Infrared (NIR, $JHK_s$) census of RR Lyrae stars (RRLs) in the globular $\omega$ Cen (NGC 5139). collected 15,472 $JHK_s$ images with 4-8m class telescopes over 15 years (2000-2015) covering sky area around cluster center 60x34 arcmin$^2$. These provided calibrated photometry for 182 out 198 RRL candidates ten to sixty measurements per band. also provide homogeneous estimates photometric amplitude 180 ($J$), 176 ($H$) and 174 ($K_s$) RRLs. data were...
New accurate and homogeneous optical UBVRI photometry has been obtained for variable stars in the Galactic globular $\omega$ Cen (NGC 5139). We secured 8202 CCD images covering a time interval of 24 years sky area 84x48 arcmin. The current data were complemented with available literature provided new, pulsation parameters (mean magnitudes, luminosity amplitudes,periods) 187 candidate RR Lyrae (RRLs). Among them we have 101 RRc (first overtone), 85 RRab (fundamental) single RRd (double-mode)...
Sky survey telescopes and powerful targeted play complementary roles in astronomy. In order to investigate the nature characteristics of motions very faint objects, a flexibly-pointed instrument capable high astrometric accuracy is an ideal complement current surveys unique tool for precision astrophysics. Such space-based mission will push frontier astrometry from evidence Earth-mass habitable worlds around nearest stars, distant Milky Way out Local Group galaxies. As we enter era James...
We present predicted relations connecting pulsational (period and amplitude of pulsation) evolutionary (mass, absolute magnitude, color) parameters, as based on a wide set convective pulsating models RR Lyrae stars with Z = 0.001, Y 0.24, mass luminosity suitable for the "old" (age > 8 Gyr) variables observed in globular clusters. The are collated sound constraints pulsators, inferred from up-to-date horizontal-branch stars, order to provide self-consistent theoretical framework analysis...
We present a new (V, B-V) color-magnitude diagram of the Carina dwarf spheroidal galaxy (dSph) that extends from tip red giant branch (RGB) down to V ∼ 25 mag. Data were collected with Wide Field Imager available at 2.2 m ESO/MPI telescope and cover an area ≈0.3 deg2 around center galaxy. confirm occurrence substantial number old stars ages 11 Gyr, together intermediate-age population 5 Gyr. Moreover, we also detected new, well-defined blue plume young main-sequence age, most, on order 1...
We present new Near-Infrared (J,K) magnitudes for 114 RR Lyrae stars in the globular cluster Omega Cen (NGC 5139) which we combine with data from literature to construct a sample of 180 J and K mean on common photometric system. This is presently largest such any stellar also updated predictions J,K-band Period-Luminosity relations both fundamental first-overtone stars, based synthetic horizontal branch models metal abundance ranging Z=0.0001 Z=0.004. By adopting variables measured...
We present a new calibration of the Strömgren metallicity index m1 using red giant (RG) stars in four globular clusters (GCs: M92, M13, NGC 1851, 47 Tuc) with ranging from -2.2 to -0.7, marginally affected by reddening [E(B - V) ≤ 0.04] and accurate (u, v, b, y) photometry. The main difference between metallicity-index-color (MIC) relations similar available literature is that we have adopted u y v colors instead b y. These stronger sensitivity effective temperature, MIC show linear slope....
We present new intermediate-band Strömgren photometry based on more than 300 u, v, b, y images of the Galactic globular cluster ω Cen. Optical data were supplemented with multiband near-infrared (NIR) (350 J, H, Ks images). The final optical–NIR catalog covers a region 20 × arcmin squared across center. use different color–color planes together proper-motion available in literature to identify candidate red-giant (RG) stars. By adopting metallicity indices, we estimate photometric for ≈4000...
We present new empirical estimates of the Delta V_HB_bump parameter for 15 Galactic globular clusters (GGCs) using accurate and homogeneous ground-based optical data. Together with similar evaluations available in literature, we ended up a sample 62 GGCs covering very broad range metal content (-2.16<=[M/H]<=-0.58 dex). Adopting metallicity scale provided either by Kraft & Ivans (2004) or Carretta et al. (2009), found that observed parameters are larger than predicted. In metal-poor regime...
We present U,B,V,I photometry of the Carina dwarf spheroidal galaxy, based on more than 4,000 CCD images. Special attention was given to photometric calibration, and precision for B,V,I bands is better 0.01 mag. compared in V,B-V V,B-I color-magnitude diagrams (CMDs) with three Globular Clusters (GCs, M53, M55, M79). find that only metal-poor GCs (M55, [Fe/H]=-1.85; [Fe/H]=-2.02 dex) provide a good match giant branch. performed similar comparison V,V-I CMD SMC intermediate-age clusters...
We present theoretical predictions concerning horizontal branch stars in globular clusters, including RR Lyrae variables, as derived from synthetic procedures collating evolutionary and pulsational constraints. On this basis, we explore the predicted behavior of pulsators a function morphology over metallicity range 0.0001 to 0.006, revealing an encouraging concordance with observed distribution fundamentalised periods metallicity. Theoretical relations connecting K magnitudes BV or VI...
We present asymptotic giant branch (AGB) models of solar metallicity, to allow the interpretation observations Galactic AGB stars, whose distances should be soon available after first release Gaia catalogue. find an abrupt change in physical and chemical properties, occurring at threshold mass ignite hot bottom burning,i.e. $3.5M_{\odot}$. Stars with below $3.5 M_{\odot}$ reach C-star stage eject into interstellar medium gas enriched carbon , nitrogen $^{17}O$. The higher counterparts evolve...
We present an extensive photometry on HB, RGB, and MSTO stars in Omega Cen. The central regions of the cluster were covered with a mosaic F435W, F625W, F658N-band data collected ACS/HST. outer reaches large set U,B,V,I-band WFI@2.2m ESO/MPI telescope. final catalogue includes ~1.7 million stars. identified ~3,200 likely HB ~12,500 brighter than subgiant branch fainter RGB bumps. morphology changes radial distance. relative number extreme decreases from ~30% to ~21% when moving center toward...