Science objectives: The goal of Arago is to follow the life cycle of matter, and
therefore the entire life of stars and planets from their formation from interstellar grains to their death and feedback into the interstellar medium
(ISM). During the formation and throughout the entire life of stars and planets, a few key basic astrophysical properties, especially magnetic fields, winds, and
binarity, influence their dynamics, and thus fundamentally impact their evolution. The associated processes directly affect the internal structure of
stars, the transport of angular momentum, and the immediate circumstellar environment. They consequently drive stellar evolution, but also define the
environments of planets, thereby influencing the formation and fate of planets surrounding the stars. Arago will allow us to obtain a full picture of the 3D
dynamical environment of stars and planets, their interactions, and explore the conditions for the emergence of life on exoplanets.
Mission: Arago is a candidate for ESA M5. It is prepared by a consortium of ~250
scientists in 21 countries. Arago will observe all types of stars with a typical magnitude between V=3 and 10. Observations will consist both in large surveys of
thousands stars and in detailed 3D mapping of ~100 carefully chosen stars. If selected by ESA, Arago will be launched in 2030 at the L2 point, and the total
nominal lifetime of the mission is 4 years.
Instrument: Arago consists of a 1.3-meter Cassegrain telescope, equipped with a
single polarimeter feeding two classical high-resolution echelle spectrographs working in the UV [119-320] nm and visible [350-888] nm spectral range. The
modulator is composed of a rotating stack of plates followed by a polarizing beam-splitter, allowing users to measure the full Stokes (IQUV) spectrum. Arago
is equipped with a CDD for the Visible domain and MCP detectors for the UV domain. Finally, an option, called Arago+, includes an additional far-UV
spectrograph, which would be provided by American collaborators.