MUSTI: a massive star far-ultraviolet spectroscopic time domain mission

MUSTI is a 40 cm-aperture high-resolution spectroscopic mission concept meeting the requirement of an ESA FAST mission. MUSTI is optimized for far-ultraviolet (FUV) time-domain astrophysics and is driven by the need to solve massive stars physics if we are to obtain reliable cosmic models. MUSTI therefore aims to obtain the observational breakthroughs needed to alleviate uncertainties in massive stars internal structure, stellar winds and (binary) evolution. The spacecraft architecture relies on a heritage platform and a secondary high-precision pointing system. The payload is a fixed-format ´echelle spectrograph covering the wavelength range 120–210 nm at a resolving power of R = λ/δλ ≈ 20,000. By combining high throughput, broad FUV coverage, and dedicated time-domain operations, MUSTI anticipates a strategic knowledge gap that will become acute in the next decade. Beside its main science aim, complementary surveys will cover classical Be stars, hot subdwarfs, young stars, and the Galactic interstellar medium.