# A survey of exoplanet phase curves with Ariel

**Authors:** Benjamin Charnay, Joao M. Mendonça, Laura Kreidberg, Nicolas B. Cowan, Jake Taylor, Taylor J. Bell, Olivier Demangeon, Billy Edwards, Carole A. Haswell, Giuseppe Morello, Lorenzo V. Mugnai, Enzo Pascale, Giovanna Tinetti, Pascal Tremblin, Robert T. Zellem  
**arXiv:** [2102.06523](https://arxiv.org/abs/2102.06523)  
**Date:** 2021-02-10  
**Summary page:** https://www.summarizepaper.com/en/paper/2102.06523v2/

## Key points

- The ESA-Ariel mission will survey around 1000 exoplanets using transit and/or secondary eclipse spectroscopy.
- Around 10% of the mission's science time will be dedicated to studying exoplanet phase curves, which provide key insights into atmospheric dynamics, composition, thermal structure, and clouds of warm exoplanets.
- The authors present the current observing strategy for studying exoplanet phase curves with Ariel, including science questions, requirements, and a list of potential targets.
- Full-orbit phase variations for 35-40 exoplanets could be observed during the 3.5-year mission using Ariel's observational strategy based on a four-tier approach (reconnaissance survey, deep survey, benchmark planets, and dedicated science programs).
- Ariel will use a one-meter telescope with simultaneous coverage from 0.5 to 7.8 µm and three instruments: FGS (3 photometric channels), NIRSpec (1.1-1.95 µm and R∼10), and AIRS (two channels: AIRS-CH0 for 1.95-3.9 µm with R=100-200; AIRS-CH1 for 3.9-7.8 µm with R=30–60).
- The authors present retrieved temperature-pressure profiles for all Ariel observations in Fig 10., highlighting the importance of studying exoplanet phase curves to gain a better understanding of exoplanetary atmospheres and complementing the scientific yield from spectroscopic transits/eclipses measurements.

## Summary

The upcoming ESA-Ariel mission is set to conduct a survey of approximately 1000 exoplanets using transit and/or secondary eclipse spectroscopy. The mission will dedicate around 10% of its science time to studying exoplanet phase curves, which will provide key insights into atmospheric dynamics, composition, thermal structure, and clouds of warm exoplanets. In this study, the authors present the current observing strategy for studying exoplanet phase curves with Ariel. They define science questions, requirements, and a list of potential targets while estimating the precision of phase curve reconstruction and atmospheric retrieval using simulated phase curves. Based on their work, the authors found that full-orbit phase variations for 35-40 exoplanets could be observed during the 3.5-year mission. This statistical sample would complement the scientific yield from spectroscopic transits/eclipses measurements and provide crucial information about exoplanetary atmospheres. Ariel's observational strategy is based on a four-tier approach that includes a reconnaissance survey (Tier 1), deep survey (Tier 2), benchmark planets (Tier 3), and dedicated science programs (Tier 4). The Ariel mission will use a one-meter telescope with simultaneous coverage from 0.5 to 7.8 µm and three instruments: FGS (3 photometric channels: VIS-Phot, FGS-1, and FGS-2), NIRSpec (1.1-1.95 µm and R∼10), and AIRS (two channels: AIRS-CH0 for 1.95-3.9 µm with R=100-200; AIRS-CH1 for 3.9-7.8 µm with R=30–60). The authors also present retrieved temperature–pressure profiles for all Ariel observations in Fig 10., which highlights the importance of studying exoplanet phase curves to gain a better understanding of exoplanetary atmospheres and complements the scientific yield from spectroscopic transits/eclipses measurements.