Galaxy Evolution in the Local Group


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.

Principal investigator

Below a list of highlights from the group activities in 2018. For a more general overview see publication list and this webpage

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.

Publications related

  • Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters . Berkeley 26, Berkeley 70, NGC 1798, and NGC 2266

    Context. Open clusters are ideal test particles for studying the formation and evolution of the Galactic disk. However, the number of clusters with information about their radial velocities and chemical compositions remains largely insufficient. Aims: We attempt to increase the number of open clusters with determinations of radial velocities and

    Carrera, R. J.

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  • The SUMO project I. A survey of multiple populations in globular clusters

    We present a general overview and the first results of the SUMO project (a SUrvey of Multiple pOpulations in Globular Clusters). The objective of this survey is the study of multiple stellar populations in the largest sample of globular clusters homogeneously analysed to date. To this aim we obtained high signal-to-noise (S/N > 50) photometry for

    Monelli, M. et al.

    Advertised on:

  • Spatially resolved LMC star formation history - I. Outside in evolution of the outer LMC disc

    We study the evolution of three fields in the outer Large Magellanic Cloud (LMC) disc (Rgc = 3.5-6.2 kpc). Their star formation history indicates a stellar population gradient such that younger stellar populations are more centrally concentrated. We identify two main star-forming epochs, separated by a period of lower activity between ≃7 and ≃4 Gyr

    Stetson, P. B. et al.

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