Tracing star and planet formation in different environments
Understanding how stars and planets form is fundamental to addressing several open questions of modern astrophysics, yet we do not have a full comprehension of the process. This impacts multiple fields, from the evolution of galaxies to the origin of our Solar System.
Although numerous space- and ground-based facilities across multiple wavelength regimes are addressing this question through diverse approaches, the WST will provide complementary yet essential ways to investigate this topic.
Small bodies as a probe of planetary evolution
Starting from our own Solar System, small bodies in planetary systems are key leftovers from the planetary formation process. They hold important information about the physical conditions prevailing in the protoplanetary disc.
Their study can shed light on the dynamics at play in the subsequent evolution of planetary systems. The WST will allow building an unprecedented picture of the small body population – comets, asteroids, TNOs, exocomets –, their composition and dynamics. For example, the IFS will enable a unified, spatially resolved study of both gas and dust components in comets, and ultimately, a coherent narrative of the cometary contribution to the Solar System evolution; the MOS will instead allow systematic surveys of Solar Systems asteroids and TNOs, allowing a full comprehension of the early and outer Solar System compositional structure.
Surveying planet-hosting stars in different environments
Advancing from the discovery of a few thousand exoplanets to tens of thousands by 2040, the field faces a new generation of questions. The formation and evolution of planetary systems cannot be understood in isolation from their stellar and Galactic environment. One of the most pressing questions in the field is to understand the role of the environment in formation and diversity of planetary systems.
The WST will perform a large-scale, high-resolution spectroscopic survey of planet-host stars and white dwarfs, spanning a broad range of Galactic environments. The WST’s unique combination of high resolution, high multiplexing, and large aperture, will allow the homogeneous determination of stellar parameters, elemental abundances, ages, and Galactic properties to infer their birth origin enabling robust statistical analyses across stellar populations.
The WST will deliver a high-precision dataset that no existing or planned facility can provide, reaching fainter magnitudes than ever before. This survey will timely complement ongoing and upcoming space missions (Gaia, TESS, PLATO, Roman). The WST will provide the most complete chemical census of planet-hosting stars and white dwarfs in high resolution to date, an essential reference for models of planet formation, and evolution and will cement WST as a cornerstone facility for exoplanet demographics.
Charting millions of young stars
The WST will use both the MOS and IFS to observe millions of young stars in the Milky Way (MW) and the Magellanic Clouds, significantly expanding the horizon within reach of current and upcoming surveys.
The determination of the 3D kinematics and full stellar characterisation will enable the investigation of the mechanisms driving the star formation process across galaxies and how this relates to Galactic structure and dynamics.
The IFS will allow the study of the dynamical evolution of massive clusters and the role of stellar feedback, in particular on protoplanetary discs; an unprecedented survey of time variability of spectral features related to accretion and outflow will be key to unlock star-disc interaction; the largest census of low-metallicity young stars will unveil the effect of metallicity on star and planet formation.
Synergies
The WST will fill a critical gap in the global astronomical infrastructure of the 2040s.
Next section
Stars, their end-points, feedback, and elements production
The WST is uniquely powerful to advance key open questions in the context of stellar physics, evolution, and nucleosynthesis.
Exoplanets, Stars, and the Milky Way with the WST
Issue #3 The WST Chronicle