Lensed hot stars with HST in the 2030s

Abstract

In the late 20th century, the Hubble Space Telescope (HST) revolutionized astronomy, showing the Universe with a detail never seen before in the ultraviolet (UV), optical and infrared (IR) bands. In the early 2020s, the James Webb Space Telescope started a similar revolution in the IR. The launch of Roman in late 2026 challenges the reign of HST in the optical band, but even after Roman's launch, HST will remain as the only telescope capable of high-quality imaging in the UV band. In the optical bands, HST provides superior resolution than Roman for point sources. Although equipped with more sensitive MOS, Roman's sensors have a pixel size about 3 times larger than HST's CCDs, hence undersampling the point-spread-function, and resulting in a worse spatial resolution. The UV-capable and higher-resolution of HST in the UV and optical band, makes HST the best instrument for specific science cases. This paper responds to the "Building a Roadmap for Hubble science into the 2030s" call and focuses on science with lensed hot stars at $z>0.5$ in the UV and optical bands, exploiting the features that makes HST the best instrument in the UV/optical until the launch of the Habitable World Observatory in the 2040s.