Stellar activity manifests itself in the form of flares, surface spots and faculae, and mass ejections from its atmosphere. Flares and superflares have been detected from active stars. The impact of the flaring UV flux on possible living organisms in close orbit planets can be very harmful, however, an atmosphere with ozone can protect them. Mass ejections also affect the planetary atmosphere, being responsible for atmospheric erosion. When an orbiting planet transits in front of the star and occults a spot or a facula, small signatures are imprinted in the transit light curve. These can be modeled to yield the physical characteristics of either spots and faculae, such as size, temperature, location, magnetic field, and lifetime. Monitoring these signatures on multiple transits yields the stellar rotation and differential rotation, and even magnetic cycles for long enough time series.
Galactic chemical evolution will be gradually unveiled in coming years thanks to large sample stellar surveys such as Gaia-ESO, Galah, and APOGEE. Sophisticated analytical tools are being developed to extract chemical compositions of millions of stars on reasonable human timescales. But these abundance surveys must be anchored in very detailed and accurate studies of individual stars. In particular, we must understand just what early Galactic nucleosynthesis was able to accomplish by careful study of individual very metal-poor stars. In this talk I will introduce this research area, and then review the efforts of our group to provide accurate abundances in low metallicity stars of two sets of important elements: the neutron-capture group (Z > 30) and the Fepeak group (Z = 21-30). Some examples will illuminate how much we know, and others will show the remaining important gaps in our knowledge that should be addressed in future studies.
We live in a vast machine, and for the last five years Gaia has been measuring the movement of its parts with revolutionary precision. From a combination of data from Gaia and ground-based surveys we want to infer how the machine is constituted, how it works now, and how it was assembled. Dynamical models are central to this enterprise. Sophisticated equilibrium models have to be fitted to the data and then used to model the Galaxy’s response to stimuli. Some early results from this major programme will be reviewed.
Massive black holes, weighing millions to billions of solar masses, inhabit the centers of today’s galaxies. Black hole masses typically scale with properties of their hosts, such as bulge mass and velocity dispersion. The progenitors of these black holes powered luminous quasars within the first billion years of the Universe. The first massive black holes must therefore have formed around the time the first stars and galaxies appeared, and then evolved along with their hosts for the past thirteen billion years. Merging massive black holes are sources of gravitational radiation at low frequency, and they complement stellar mass black holes in the gravitational wave spectrum. I will discuss some aspects of the cosmic evolution of massive black holes, from their formation to their growth, dynamics and mergers and how different physical processes shape the relation between black holes and galaxies.
The first billion years represents the final frontier in assembling a coherent picture of cosmic history. During this period the first stellar systems formed, bathing the Universe in ultraviolet radiation that likely played a key role in ionising intergalactic hydrogen. Deep imaging and spectroscopic observations are now probing these early epochs addressing questions such as when and how galaxies formed and whether they were primarily responsible for this cosmic reionisation. Upcoming facilities such as the James Webb Space Telescope and future ground-based optical and radio facilities will enable further progress. I will discuss the current challenges and future prospects.
I will summarize our current understanding of the processes that govern the formation and co-evolution of galaxies and their supermassive black holes (SMBH). I will pose several of the most fundamental shortcomings of our current models and then examine how they may be addressed by the effects of the feedback provided by massive stars and actively growing SMBH. My focus will be on what we have learned so far (largely from observations of the contemporary universe), and I will conclude by describing future prospects using a new generation of facilities. I will do my best to give talk that minimizes jargon and stresses the basic underlying physical processes.
After almost 57 years since its foundation, ESO (European Organisation for Astronomical Research in the Southern Hemisphere) has become a world-leading organisation in ground-based astronomy. ESO’s mission is precisely building and operating the most powerful telescopes and to foster cooperation in astronomy. ESO operates the Very Large Telescope (VLT), the VLT interferometer in Paranal, and two survey telescopes (VST and VISTA) in Paranal, two 3.6m telescopes in La Silla and the APEX submillimeter telescope in Chajnantor at 5000 m altitude. Together with our partners in North America and East Asia, we operate the ALMA Large Millmeter/submillimeter Array also in Chajnantor, the most powerful facility at these wavelengths. These facilities enable more than 1000 refereed papers per year, some of which are truly transformational. Further, ESO is building what will be the largest optical/infrared telescope in the world – the ELT (Extremely Large Telescope) to be erected in Armazones, which will be operated from 2025 onwards as part of the Paranal observatory. In the same area, ESO will host and operate the Southern array of CTA (Cherenkov Telescope Array), which is now completing its design study. Thanks to the support from its member states and partners, ESO offers very competitive opportunities for astronomical research, cooperation for the development of advanced instrumentation, industrial opportunities and training for early career scientists and engineers.