Atmospheric Characterisation with the Twinkle Space Telescope Following Advances from JWST Observations

Abstract

The Twinkle Space Telescope is a satellite designed for spectroscopic observations of a wide range of extrasolar and solar system objects. Equipped with a 0.45 m diameter telescope and a spectrometer covering from 0.5 to 4.5 μm simultaneously, Twinkle will be launched in a sun-synchronous, low-Earth orbit, and it is expected to operate for seven years. Twinkle is developed, managed and operated by Blue Skies Space (BSSL), a space science data company whose vision is to accelerate and expand the availability of new, high-quality datasets to researchers worldwide, complementing the space-observatories delivered by government space agencies. Over its life-time, Twinkle will conduct large-scale survey programs. The scientific objectives and observational strategy of these surveys are defined by researchers who join the Science Team. Leveraging advances made possible by recent observations with the James Webb Space Telescope, we present here updated simulations evaluating Twinkle's observational capabilities in the context of exoplanet atmospheres. Through retrieval analyses of HD 209458 b, WASP-107 b, GJ 3470 b, and 55 Cnc e, we demonstrate how increasing observational investment enhances the retrieval of atmospheric parameters and molecular abundances. Our sensitivity study highlights Twinkle's capability to detect less abundant/detectable molecules depending on the observing strategies adopted. This work provides practical guidance for developing targeted observational strategies to maximize Twinkle's scientific return.

Figures (20)

• Figure 1: The sweep of Twinkle's FoR and location of currently known exoplanets (red) and TESS objects of interest (blue).
• Figure 2: Known planets and TOIs capable of achieving median SNR thresholds within 30 observations at native resolution. They are distributed based on planet radius versus host star K magnitude. Different shapes demonstrate the preferred type of observation. Top Panel: SNR $\geq$ 3; Middle Panel: SNR $\geq$ 5; Bottom Panel: SNR $\geq$ 7.
• Figure 3: Comparison of the JWST and Twinkle-simulated spectrum for HD 209458 b, highlighting the spectral contributions of various molecular absorbers and scattering effects. The error bars on the spectrum are based on simulations of 10 transits, and the spectra are fitted under the assumption of chemical equilibrium. For clarity, spectral contributions from effects that are insignificant have been omitted. The HST data points have been shifted downward by 100 ppm.
• Figure 4: Posterior distributions of retrieved parameters from retrieval analysis of HD 209458 b assuming chemical equilibrium. Green: 1 transit; Purple: 10 transits.
• Figure 5: Comparison of JWST transmission spectrum and Twinkle-simulated spectrum, with spectral contributions of various molecule absorbers and scattering effects for WASP-107 b. Error bar on spectrum is simulated with observation of 6 transits (SNR = 10). The spectra is fitted assuming free chemistry. The JWST data points were offset upward by 300 ppm.