Mission concept

We propose to study a concept composed of a UV+visible spectropolarimeter, aiming at observing stars to study various stellar and circumstellar physical processes and in particular magnetospheres. The main scientific requirements are based on the main science drivers (stellar physics). A wide range of other astrophysical issues, from the ISM to Novae, can however also be studied with this type of instrument and little additional constraints on the instrumental requirements. Other scientific topic, such as distant galaxies or AGNs, could also be studied with a UV spectrograph to the condition that a much larger mirror is used.

Small dedicated mission concept

The "small mission" concept would be ideal for all the main science drivers. Even with a small mirror (such as the one of IUE), the UV spectrograph would be much more efficient than its predecessor IUE thanks to the huge improvement in detector technology. It would also be more focused than the spectrographs on HST or WSO because it would be dedicated to solving a limited number of science problems and focused on long-term monitoring of bright stars, with requirements designed specifically for these studies. The UV+optical spectropolarimeter would nicely complement the spectrograph to multiply tenfold the capabilities of extracting information on magnetospheres, winds, and stellar and disk magnetic fields.

A dedicted mission would allow to obtain observing time series on a significant number of stars, which would be extremely valuable to reach our scientific goals. this is thus the preferred option.

Instrument on a LUVO concept

The instrument we propose to develop could benefit to other science topics than stellar physics if it would be placed on a large UV observatory (LUVO). In this case, we propose to develop only the instrument (UV+visible spectropolarimeter) and collaborate with a LUVO team. However, more flexibility and complexity might then be needed for the instrument, e.g. a MOS/IFU mode or an imaging mode. In addition the spectropolarimeter would probably mostly serve the stellar physics community.