The objective of this project is to understand the formation and evolution of galaxies of different morphological types, using the many local examples that can be resolved into individual stars, hence performing the so-called "galactic archaelogy". This branch of research is one of the main drivers of major international projects/facilities, such as the on-going Gaia mission and SDSS surveys, and the planned WHT/WEAVE, LSST, VISTA/4MOST, DESI, E-ELT/HARMONI, to name a few. This ensures that Galactic Archaelogy will be at the forefront of astronomical research for a long time.
Because of their relative proximity, Local Group galaxies can be resolved into stars. Therefore we can study them with a detail impossible elsewhere with present-day facilities and derive their evolutionary history using a set of complementary techniques. On the one hand, using deep photometry reaching the old main sequence turn-offs, it is possible to derive the full star formation history over the entire galaxy's life. Spectroscopic studies of individual stars add direct information on the kinematics and chemical abundances of the different stellar populations; for the most nearby systems, the inclusion of accurate astrometric measurements yields information on the orbital motion of the system and can even deliver the full 6D phase-space information of sub-samples of stars. Third, the study of variable stars such as Cepheids and RR Lyrae provide independent constraints on metallicities and ages of the populations they belong to. These observations offer invaluable, rich information to models of the formation and evolution of galactic structures in a cosmological context.
The Local Group and its immediate surroundings contain about 80 galaxies of different morphological types. Among these, the largest are spiral galaxies (the Milky Way, M31 and M33), a dozen of them are (dwarf) irregulars and the rest are early-type systems. Thus, we can study galaxies of different morphological types, from the Milky Way down to the smallest galactic scales, which are those challenging our understanding of what a "galaxy" is. We also aim at exploiting the detailed information from resolved stellar population studies to test the performance and applicability of integrated light techniques, which are applied to distant stellar systems.
Members of the project
Highlights and results
Below a list of highlights from the group activities in 2018. For a more general overview see publication list and this webpage.
- Several structures in the Large Magellanic Clouds have been studied: its bar and internal disc (Monteagudo-Narvion et al. 2018), a ring-like over-density in the disc (Choi et al. 2018a) and a deformation induced by tidal forces in the external disc (Choi et al. 2018b). Furthermore a large-scale reddening map was obtained.
- In Fritz, Battaglia et al. (2018) we have very timely exploited the second release of data from the Gaia mission to provide the determination of the systemic motions and orbital parameters for the largest number of Milky Way satellites to date. This has resulted into a ESA story and an IAC press release.
- In Cicuendez & Battaglia (2018) we have unveiled signs of accretion of a smaller galaxy in the Sextans dSph. This events should become increasingly rare at low masses and the discovery makes of Sextans the smallest system in which some signs have been detected so far. The work has resulted in a IAC press release and has made it to the IAC gallery of results.
- In Taibi, Battaglia et al. (2018) we took an important step forward in assessing the internal kinematics of the Cetus dwarf spheroidal galaxy and carried out the first wide-area spectroscopic determination of its metallicity properties. With our analysis, Cetus adds to the growing scatter in stellar-dark matter halo properties in low-mass galactic systems.
- A considerable amount of time has been allocated for observations with the Hubble Space Telescope. 32 orbits will be devoted to study the variable stars content of the VV124 and Kkr25 galaxies.
Spatial dependence of the star formation history in the central regions of the Fornax dwarf spheroidal galaxy
We present the star formation history (SFH) and the age-metallicity relation (AMR) in three fields of the Fornax dwarf spheroidal galaxy. They sample a region spanning from the centre of the galaxy to beyond one core radius, which allows studying galactocentric gradients. In all the cases, we found stars as old as 12 Gyr, together with intermediatedel Pino, A. et al.
The near-infrared Ca II triplet as a metallicity indicator - II. Extension to extremely metal-poor metallicity regimes
We extend our previous calibration of the infrared Ca II triplet (CaT) as a metallicity indicator to the metal-poor regime by including observations of 55 field stars with [Fe/H] down to -4.0 dex. While we previously solved the saturation at high metallicity using a combination of a Lorentzian and a Gaussian to reproduce the line profiles, in thisCarrera, R. et al.
The extended structure of the dwarf irregular galaxy Sagittarius
We present a detailed study of the stellar and H i structure of the dwarf irregular galaxy Sagittarius. We use new deep and wide field photometry to trace the surface brightness profile of the galaxy out to ≃5.0' (corresponding to ≃1600 pc) and down to μV ≃ 30.0 mag/arcsec2, thus showing that the stellar body of the galaxy is much more extendedBeccari, G. et al.