The general aim of the project is to research the structure, evolutionary history and formation of galaxies through the study of their resolved stellar populations, both from photometry and spectroscopy. The group research concentrates in the most nearby objects, namely the Local Group galaxies including the Milky Way and M33 under the hypothesis that they are a good representation of the general population of galaxies in the Universe.
The project can be divided in four research lines:
I. Star formation history in the Local Group.
The goal is to characterise the spatial and temporal structure of the galaxies of the Local Group through the observations of individual stars. The fundamental aim is to derive the detailed star formation history (SFH) of a given galaxy in all its evolutionary stages, in order to determine the impact of cosmological (e.g. reionization, self-shielding) and local processes (e.g. gas sweeping by supernovas, tidal forces, stellar migration).
II. Multiple stellar populations in globular clusters.
At odds of what it is classically predicted, there is evidence that globular clusters (GC) host more than one stellar population with different chemical composition. HST photometric observations of GC show strong evidence of multiple main sequences in the CMDs. The aim of this line is to characterise the aforementioned multiple populations in GC.
III. Structure and formation of the Milky Way.
The main purpose of this research line is to study the Milky Way via by using GAIA data (spacebased), and the ESO-VVV survey (Vista Telescope). These data are going to provide a perfect opportunity to study the star formation history of the Galactic disk and bulge. In order to use GAIA and VVV data we need to adapt the tools developed by our group to study stellar populations.
IV. Stellar evolution and synthetic color-magnitude diagram.
We have developed a new stellar evolutionary library. There is the need in the scientific community to increase the reliability and accuracy in the stellar models computation using the most updated results in Physics, such as the equation of state, new opacities, and nuclear sections.
- Development of the web site http://basti-iac.oa-teramo.inaf.it for the BaSTI stellar evolution library
- Obtention of near-infrared PSF photometry of the full VVV disk region (220 sq. deg between 294.7° ≤ l ≤ 350.0° and |b| ≤ 2.25°) in J and Ks bands
- Computation of a open access data base of "cromosomic maps" for all the object of the "HST Legacy Project on Globular Clusters".
- Determination of the star formation history of three Ultra-fain Dwarfs (UFD): Bootes I, Canes Venatici II y Leo IV
EMIR, the near-infrared camera and multi-object spectrograph for the GTC. EMIR at GTC
We present EMIR, a powerful near-infrared (NIR) camera and multi-object spectrograph (MOS) installed at the Nasmyth focus of the 10.4 m GTC. EMIR was commissioned in mid-2016 and is offered as a common-user instrument. It provides spectral coverage of 0.9-2.5 µm over a field of view (FOV) of 6.67' × 6.67' in imaging mode, and 6.67' × 4' inGarzón, F. et al.
Analysing the structure of the bulge with Mira variables
Context. The Galactic bulge at latitude 4 < |b|(deg) < 10 was claimed to show an X-shape, which means that stellar density distributions along the line of sight have a double peak. However, this double peak is only observed with the red-clump population, and doubt has been cast on its use as a perfect standard candle. As such, a boxy bulge withoutChrobáková, Ž. et al.
StraKLIP: A Novel Pipeline for Detection and Characterization of Close-in Faint Companions through the Karhunen-Loéve Image Processing Algorithm
We present a new pipeline developed to detect and characterize faint astronomical companions at small angular separation from the host star using sets of wide-field imaging observations not specifically designed for high-contrast imaging analysis. The core of the pipeline relies on Karhunen-Loéve truncated transformation of the reference pointStrampelli, Giovanni M. et al.
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIII. Proper-motion Catalogs and Internal Kinematics
A number of studies based on the data collected by the Hubble Space Telescope (HST) GO-13297 program "HST Legacy Survey of Galactic Globular Clusters: Shedding UV Light on Their Populations and Formation" have investigated the photometric properties of a large sample of Galactic globular clusters and revolutionized our understanding of theirLibralato, Mattia et al.
Warp and flare of the Galactic disc revealed with supergiants by Gaia EDR3
Context. The outer Galactic disc contains some features such as the warp and flare, whose origin is still debated. The Gaia data provide an excellent opportunity to probe the Galactic disc at large distances and study these features. Aims: We derive the density distributions of the average (old) whole population and the supergiants (representativeChrobáková, Ž. et al.
Detection of Gravitational Redshift in Open Cluster Nondegenerate Stars
A key observational prediction of Einstein's Equivalence Principle is that light undergoes redshift when it escapes from a gravitational field. Although astrophysics provides a wide variety of physical conditions in which this redshift should be significant, until very recently the observational evidence for this gravitational effect was limited toGutiérrez, Carlos M. et al.
SEGUE-2: Old Milky Way Stars Near and Far
The Sloan Extension for Galactic Understanding and Exploration 2 (SEGUE-2) obtained 128,288 low-resolution spectra (R ~ 1800) of 118,958 unique stars in the first year of the Sloan Digital Sky Survey III (2008-2009). SEGUE-2 targeted prioritized distant halo tracers (blue horizontal-branch stars, K giants, and M giants) and metal-poor orRockosi, Constance M. et al.
Internal rotation of Milky Way dwarf spheroidal satellites with Gaia Early Data Release 3
We present an analysis of the kinematics of 14 satellites of the Milky Way (MW). We use proper motions (PMs) from the Gaia Early Data Release 3 (EDR3) and line-of-sight velocities (vlos) available in the literature to derive the systemic 3D motion of these systems. For six of them, namely the Carina, Draco, Fornax, Sculptor, Sextans, and Ursa MinorMartínez-García, Alberto Manuel et al.
Constraining the solar neighbourhood age-metallicity relation from white dwarf-main sequence binaries
The age-metallicity relation (AMR) is a fundamental tool for constraining the chemical evolution of the Galactic disc. In this work, we analyse the observational properties of this relation using binary stars that have not interacted consisting of a white dwarf (WD) - from which we can derive the total age of the system - and a main sequence (MS)Rebassa-Mansergas, A. et al.
Exploring nine simultaneously occurring transients on April 12th 1950
Nine point sources appeared within half an hour on a region within ∼? 10 arcmin of a red-sensitive photographic plate taken in April 1950 as part of the historic Palomar Sky Survey. All nine sources are absent on both previous and later photographic images, and absent in modern surveys with CCD detectors which go several magnitudes deeper. WeVillarroel, Beatriz et al.
The Cluster HEritage project with XMM-Newton: Mass Assembly and Thermodynamics at the Endpoint of structure formation. I. Programme overview
The Cluster HEritage project with XMM-Newton - Mass Assembly and Thermodynamics at the Endpoint of structure formation (CHEX-MATE) is a three-mega-second Multi-Year Heritage Programme to obtain X-ray observations of a minimally-biased, signal-to-noise-limited sample of 118 galaxy clusters detected by Planck through the Sunyaev-Zeldovich effect. TheCHEX-MATE Collaboration et al.
Interactions between large-scale radio structures and gas in a sample of optically selected type 2 quasars
Context. The role of radio mode feedback in non radio-loud quasars needs to be explored in depth to determine its true importance. Its effects can be identified based on the evidence of interactions between the radio structures and the ambient ionised gas. Aims: We investigate this interaction in a sample of 13 optically selected type 2 quasarsVillar Martín, M. et al.
A Case against a Significant Detection of Precession in the Galactic Warp
Recent studies of warp kinematics using Gaia DR2 data have produced detections of warp precession for the first time, which greatly exceeds theoretical predictions of models. However, this detection assumes a warp model derived for a young population (few tens of megayears) to fit velocities of an average older stellar population of the thin diskChrobáková, Ž. et al.
Exact Semianalytical Calculation of Rotation Curves with Bekenstein-Milgrom Nonrelativistic MOND
Astronomers derive MOdified Newtonian Dynamics (MOND) rotation curves using the simple algebraic rule of calculating the acceleration as equal to the Newtonian acceleration (a) divided by some factor μ(a). However, there are velocity differences between this simple rule and the calculation derived from more sophisticated MOND versions such as AQUALLópez-Corredoira, M. et al.
Multiple Populations in Low-mass Globular Clusters: Palomar 13
Since the discovery of chemically peculiar stars in globular clusters in the last century, the study of multiple populations has become increasingly important, given that chemical inhomogeneity is found in almost all globular clusters. Despite various proposed theories attempting to explain this phenomenon, fitting all the observational evidence inTang, Baitian et al.
Updated BaSTI Stellar Evolution Models and Isochrones. II. α-enhanced Calculations
This is the second paper of a series devoted to presenting an updated release of the BaSTI (a Bag of Stellar Tracks and Isochrones) stellar model and isochrone library. Following the publication of the updated solar-scaled library, here we present the library for an α-enhanced heavy element distribution. These new α-enhanced models account for allPietrinferni, Adriano et al.
PSR B0656+14: the unified outlook from the infrared to X-rays
We report detection of PSR B0656+14 with the Gran Telescopio Canarias in narrow optical F657, F754, F802, and F902 and near-infrared JHKs bands. The pulsar detection in the Ks band extends its spectrum to 2.2 $\mu$ m and confirms its flux increase towards the infrared. We also present a thorough analysis of the optical spectrum obtained by us withZharikov, S. et al.
HST Survey of the Orion Nebula Cluster in the H<SUB>2</SUB>O 1.4 μm Absorption Band. III. The Population of Substellar Binary Companions
We present new results concerning the substellar binary population in the Orion Nebula Cluster (ONC). Using the Karhunen-Loève Image Projection algorithm, we have reprocessed images taken with the IR channel of the Wide Field Camera 3 mounted on the Hubble Space Telescope to unveil faint, close companions in the wings of the stellar point-spreadStrampelli, Giovanni M. et al.
Statistical analysis of Galactic globular cluster type properties
The analysis of pseudo-colour diagrams, the so-called chromosome maps, of Galactic globular clusters (GCs) permits to classify them into type I and type II clusters. Type II GCs are characterized by an above-the-average complexity of their chromosome maps and some of them are known to display star-to-star variations of slow neutron-capture reactionSimioni, M. et al.
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XX. Ages of Single and Multiple Stellar Populations in Seven Bulge Globular Clusters
In the present work we analyzed seven globular clusters (GCs) selected from their location in the Galactic bulge and with metallicity values in the range -1.30 ≲ [Fe/H] ≲ -0.50. The aim of this work is first to derive cluster ages assuming single stellar populations and second to identify the stars from first (1G) and second generations (2G) fromOliveira, R. A. P. et al.