Periodic Reporting for period 1 - WDPlanets (Planetary systems around white dwarfs)
Reporting period: 2021-10-01 to 2023-03-31
Whereas it is now well-established that planetary systems are formed around most Sun-like stars, relatively little is known regarding their evolution once their host stars run out of fuel, and evolve into white dwarfs, the burnt-out leftovers left behind by most stars in the Galaxy. Over the past decade, we have begun to discover the remains of planetary systems orbiting a number of white dwarfs, and we have learned that these systems can inform us about the general formation and evolution of planets in a way that is complementary to the studies of planets orbiting Sun-like stars. However, this emerging area of exo-planet research has so far been limited by the very small number of systems that are available for detailed studies. Of particular importance is that the study of planetary systems around white dwarfs is that they provide information on the bulk compositions of exo-planets, which is fundamentally important for theoretical models of planet formation.
Within this project, we will obtain high-quality observational data of ~200,000 white dwarfs using a range of new, large international facilities, increasing the sample of known white dwarfs by about a factor ten. Within this very large sample, we will identify ~1000 white dwarfs with planetary systems that are suitable for detailed analyses. Using sophisticated computer simulations of white dwarf atmospheres, we will measure the bulk abundances of these systems, and compile the first large data base of exo-planet abundances. We will use these data to investigate the statistical properties of exo-planetary systems, and answer one fundamental question: Is our Solar System unique in any way, or can we expect other planetary systems to be composed of material that is very similar to our local environment? We will also investigate the complex processes involved in the disruption of planetary bodies in the strong gravitational field of white dwarfs, and the subsequent formation of debris discs around these stars.
The overall goal of the project is to develop this new, innovative and still small research area into one of the fundamental pillars of exo-planet research, contributing major insight into our understanding of the formation and evolution of planetary systems.
Within this project, we will obtain high-quality observational data of ~200,000 white dwarfs using a range of new, large international facilities, increasing the sample of known white dwarfs by about a factor ten. Within this very large sample, we will identify ~1000 white dwarfs with planetary systems that are suitable for detailed analyses. Using sophisticated computer simulations of white dwarf atmospheres, we will measure the bulk abundances of these systems, and compile the first large data base of exo-planet abundances. We will use these data to investigate the statistical properties of exo-planetary systems, and answer one fundamental question: Is our Solar System unique in any way, or can we expect other planetary systems to be composed of material that is very similar to our local environment? We will also investigate the complex processes involved in the disruption of planetary bodies in the strong gravitational field of white dwarfs, and the subsequent formation of debris discs around these stars.
The overall goal of the project is to develop this new, innovative and still small research area into one of the fundamental pillars of exo-planet research, contributing major insight into our understanding of the formation and evolution of planetary systems.
Within the first reporting period, we have focused largely on the survey design for three spectroscopic surveys (DESI, WEAVE and SDSS-V), the development of software that combines the data from these facilities, plus photometric observations from ZTF, into a homogenous format. We have also made significant process in the development of the software analysis tools that we will need to work with this very large data set, and we have carried out a number of studies into systematic effects and uncertainties that will have to be taken into account in the interpretation. We have published a total of sixteen refereed publications, several of those outline pilot studies of the analysis work that will now be rolled out to the full survey data.
Progress in the study of white dwarfs, and there planetary systems, has so far been limited by the small numbers of these systems. Because white dwarfs are small, Earth-sized, they require substantial amounts of observing efforts to secure high-quality data, and we have been spear-heading the follow-up observations of white dwarfs by the newly commissioned large spectroscopic surveys DESI, SDSS-V, and WEAVE, which will increase the number of white dwarfs with high-quality data by a factor ten. In addition, we are also working on the software suite required to analyse these data in a streamlined fashion, as opposed to the past ad-hoc object-by-object approach. We will make these tools available to the community, to facilitate the analysis of white dwarf observations.