On the Information Content of Ariel Transmission Spectra: Reassessing the Tier System
Fuente:
arXiv
Enregistré dans:
| Auteurs principaux: | , , , |
|---|---|
| Format: | Preprint |
| Publié: |
2026
|
| Sujets: | |
| Accès en ligne: | |
| Tags: |
Ajouter un tag
Pas de tags, Soyez le premier à ajouter un tag!
|
| _version_ | 1866914461004070912 |
|---|---|
| author | Radica, Michael Cowan, Nicolas B. Cloutier, Ryan Wang, Leo Yang |
| author_facet | Radica, Michael Cowan, Nicolas B. Cloutier, Ryan Wang, Leo Yang |
| contents | The European Space Agency's Ariel mission will conduct a survey of the atmospheric properties of exoplanets around bright stars. The mission is nominally divided into three Tiers. The Tier 1 survey will consist of low-precision observations of ~1000 planets, with a subset of these included in the higher-precision Tier 2 survey expected to be necessary for atmospheric characterization. Tier 3 will be repeated observations of a small number of benchmark planets. Though previous studies have assessed the ability of Ariel to uncover population-level trends, they have generally presupposed a given Tier. Here we interrogate this assumption and assess the information content of Ariel transmission spectra as a function of Tier for three benchmark planets: a hot-Saturn, warm-Neptune, and temperate sub-Neptune. We simulate a grid of Ariel transit spectra at different Tiers for each target and use retrievals to assess which chemical species are detectable. We find that for giant planets like a hot-Saturn or warm-Neptune, Tier 1-quality observations are sufficient for <1.5dex constraints on H2O and CO2, irrespective of the presence of clouds -- meaning important chemical insights are already obtainable in the Tier 1 survey. Moving to Tiers 2 and 3 result in an incremental increase in precision as well as other molecules becoming detectable in certain scenarios (e.g., H2S, CO). Tier 1 observations are also sufficient to constrain CH4 in a cloud-free, temperate sub-Neptune, whereas observations with at least Tier 2 precision are necessary if the atmosphere is cloudy. The number of transits necessary to reach this precision, however, may be prohibitive for the inclusion of temperate sub-Neptunes in even the Tier 1 survey. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_07598 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | On the Information Content of Ariel Transmission Spectra: Reassessing the Tier System Radica, Michael Cowan, Nicolas B. Cloutier, Ryan Wang, Leo Yang Earth and Planetary Astrophysics Instrumentation and Methods for Astrophysics The European Space Agency's Ariel mission will conduct a survey of the atmospheric properties of exoplanets around bright stars. The mission is nominally divided into three Tiers. The Tier 1 survey will consist of low-precision observations of ~1000 planets, with a subset of these included in the higher-precision Tier 2 survey expected to be necessary for atmospheric characterization. Tier 3 will be repeated observations of a small number of benchmark planets. Though previous studies have assessed the ability of Ariel to uncover population-level trends, they have generally presupposed a given Tier. Here we interrogate this assumption and assess the information content of Ariel transmission spectra as a function of Tier for three benchmark planets: a hot-Saturn, warm-Neptune, and temperate sub-Neptune. We simulate a grid of Ariel transit spectra at different Tiers for each target and use retrievals to assess which chemical species are detectable. We find that for giant planets like a hot-Saturn or warm-Neptune, Tier 1-quality observations are sufficient for <1.5dex constraints on H2O and CO2, irrespective of the presence of clouds -- meaning important chemical insights are already obtainable in the Tier 1 survey. Moving to Tiers 2 and 3 result in an incremental increase in precision as well as other molecules becoming detectable in certain scenarios (e.g., H2S, CO). Tier 1 observations are also sufficient to constrain CH4 in a cloud-free, temperate sub-Neptune, whereas observations with at least Tier 2 precision are necessary if the atmosphere is cloudy. The number of transits necessary to reach this precision, however, may be prohibitive for the inclusion of temperate sub-Neptunes in even the Tier 1 survey. |
| title | On the Information Content of Ariel Transmission Spectra: Reassessing the Tier System |
| topic | Earth and Planetary Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2604.07598 |