TINI: Tubingen-IIA Nebular gas Investigator
The far ultraviolet (FUV, 91.2 nm to 180 nm) is the wavelength region with the greatest density of astronomical absorption and emission lines. However, despite of being one of the most exciting parts of the astrophysical spectrum, FUV missions are rare, partly due to the need for an instrument with a windowless, open-face detector.
TINI, the Tuebingen-IIA Nebular gas Investigator, is a proposed space mission that addresses this unique wavelength range with a 12U imaging spectrograph tailored for observations of diffuse sources like nebulae or the ISM. It features a field-of-view of 0.7° with 13" spatial resolution and a spectral resolution of 0.8Å (resolving power R≈2000).
Simulated spectrum of the crab nebula as seen with TINI. Flux data from the Hopkins Ultraviolet Telescope (HUT) was used as simulation input, taken from the MAST database.
Science Case
The primary scientific objective of the TINI mission is emission line spectroscopy of extended regions in the far ultraviolet (FUV). The objects of interest comprise e.g. supernova remnants (SRN), planetary nebulae, and galaxy clusters. Furthermore, the instrument is ideal to observe regions of hot gas, molecular gas, halo gas, and dust scattering, both Galactic and extragalactic, from the interior of galaxy clusters to the cosmic web. If pointing stability and orbit allow, even pointed observations of active galactic nuclei (AGN) are possible. The goal is to trace the underlying astrophysical processes at work in these objects by generating temperature, density, and velocity distributions and mapping chemical compositions.
Instrument
- Observing band: 90 - 180 nm
- Field of view: 0.7 deg x 13" (slit)
- Spatial Resolution: 13"
- Spectral resolution: 0.08 nm
- Primary aperture: 200 mm
- Primary Mirror: Zerrodur with Al + SiC coating
- Grating: 1800 lines/mm
- Dimension: 600 x 400 x 350 mm
- Mass: 17 Kg
- Power: 15W
Mission Concept
A main design driver for the TINI mission was the aim for a configuration that can be achieved with minimal risks. Thus, the applied technologies were selected carefully under this premise and a simple, small, and low-mass instrument design was chosen. Also the collaboration of only two teams, both of which have experience in delivering UV instruments for space-flights, keeps the number of interfaces low and thus simplifies the management.
TINI fits in a 12U package and is planned as a secondary instrument on a larger platform. The launch constraints are minimal. While a low Earth orbit (LEO) – either equatorial or polar – is preferred, a geosynchronous orbit is also acceptable.