The Third Option: Color Phase Curves to Characterize the Atmospheres of Temperate Rocky Exoplanets

Fuente: arXiv
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Hauptverfasser: Deming, Drake, Lincowski, Andrew, Kreidberg, Laura, Currie, Miles, Desert, Jean-Michel, Fu, Guangwei, Lustig-Yaeger, Jacob, Meadows, Victoria, Snellen, Ignas
Format: Preprint
Veröffentlicht: 2026
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author Deming, Drake
Lincowski, Andrew
Kreidberg, Laura
Currie, Miles
Desert, Jean-Michel
Fu, Guangwei
Lustig-Yaeger, Jacob
Meadows, Victoria
Snellen, Ignas
author_facet Deming, Drake
Lincowski, Andrew
Kreidberg, Laura
Currie, Miles
Desert, Jean-Michel
Fu, Guangwei
Lustig-Yaeger, Jacob
Meadows, Victoria
Snellen, Ignas
contents Detecting and characterizing the atmospheres of rocky exoplanets has proven to be challenging for JWST. Transit spectroscopy of the TRAPPIST-1 planets has been impacted by the effects of spots and faculae on the host star. Secondary eclipses have detected hot rocks, but evidence for atmospheres has been difficult to obtain. However, there is a third option that we call color phase curves. This method will apply to synchronously rotating non-transiting planets as well as transiting planets. A color phase curve uses photometry at a long-IR wavelength near the peak of the planetary thermal emission (e.g., 21 microns) divided by photometry at a shorter wavelength where the star dominates more strongly (e.g., 12 microns). We avoid wavelengths having potentially strong molecular absorption (e.g., 15 microns) to minimize degeneracies in the color phase curve, and we aim to detect and characterize the planetary atmosphere via its longitudinal heat transfer. The ratio of two wavelengths observed nearly simultaneously is designed to isolate thermal emission from the planet, discriminate against the star, and largely cancel instrumental systematic effects. Moreover, we show that invoking mass-radius relations, and using self-consistent physical models, will permit the longitudinal heat transfer to be measured independent of the orbital inclination. Radial velocity surveys are detecting many new exoplanets, including temperate rocky worlds with Earth-like masses. Most of those planets will not transit, but color phase curves have the potential to detect and characterize their atmospheres.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20966
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Third Option: Color Phase Curves to Characterize the Atmospheres of Temperate Rocky Exoplanets
Deming, Drake
Lincowski, Andrew
Kreidberg, Laura
Currie, Miles
Desert, Jean-Michel
Fu, Guangwei
Lustig-Yaeger, Jacob
Meadows, Victoria
Snellen, Ignas
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
Detecting and characterizing the atmospheres of rocky exoplanets has proven to be challenging for JWST. Transit spectroscopy of the TRAPPIST-1 planets has been impacted by the effects of spots and faculae on the host star. Secondary eclipses have detected hot rocks, but evidence for atmospheres has been difficult to obtain. However, there is a third option that we call color phase curves. This method will apply to synchronously rotating non-transiting planets as well as transiting planets. A color phase curve uses photometry at a long-IR wavelength near the peak of the planetary thermal emission (e.g., 21 microns) divided by photometry at a shorter wavelength where the star dominates more strongly (e.g., 12 microns). We avoid wavelengths having potentially strong molecular absorption (e.g., 15 microns) to minimize degeneracies in the color phase curve, and we aim to detect and characterize the planetary atmosphere via its longitudinal heat transfer. The ratio of two wavelengths observed nearly simultaneously is designed to isolate thermal emission from the planet, discriminate against the star, and largely cancel instrumental systematic effects. Moreover, we show that invoking mass-radius relations, and using self-consistent physical models, will permit the longitudinal heat transfer to be measured independent of the orbital inclination. Radial velocity surveys are detecting many new exoplanets, including temperate rocky worlds with Earth-like masses. Most of those planets will not transit, but color phase curves have the potential to detect and characterize their atmospheres.
title The Third Option: Color Phase Curves to Characterize the Atmospheres of Temperate Rocky Exoplanets
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2601.20966