Probing 2D Asymmetries of an Exoplanet Atmosphere from Chromatic Transit Variation

Fuente: arXiv
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Autori principali: Tada, Shotaro, Kawahara, Hajime, Kawashima, Yui, Kotani, Takayuki, Masuda, Kento
Natura: Preprint
Pubblicazione: 2025
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author Tada, Shotaro
Kawahara, Hajime
Kawashima, Yui
Kotani, Takayuki
Masuda, Kento
author_facet Tada, Shotaro
Kawahara, Hajime
Kawashima, Yui
Kotani, Takayuki
Masuda, Kento
contents We propose a new method for investigating atmospheric inhomogeneities in exoplanets through transmission spectroscopy. Our approach links chromatic variations in conventional transit model parameters (central transit time, total and full durations, and transit depth) to atmospheric asymmetries. By separately analyzing atmospheric asymmetries during ingress and egress, we can derive clear connections between these variations and the underlying asymmetries of the planetary limbs. Additionally, this approach enables us to investigate differences between the limbs slightly offset from the terminator on the dayside and the nightside. We applied this method to JWST's NIRSpec/G395H observations of the hot Saturn exoplanet WASP-39 b. Our analysis suggests a higher abundance of CO2 on the evening limb compared to the morning limb and indicates a greater probability of SO2 on the limb slightly offset from the terminator on the dayside relative to the nightside. These findings highlight the potential of our method to enhance the understanding of photochemical processes in exoplanetary atmospheres.
format Preprint
id arxiv_https___arxiv_org_abs_2503_08988
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Probing 2D Asymmetries of an Exoplanet Atmosphere from Chromatic Transit Variation
Tada, Shotaro
Kawahara, Hajime
Kawashima, Yui
Kotani, Takayuki
Masuda, Kento
Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
We propose a new method for investigating atmospheric inhomogeneities in exoplanets through transmission spectroscopy. Our approach links chromatic variations in conventional transit model parameters (central transit time, total and full durations, and transit depth) to atmospheric asymmetries. By separately analyzing atmospheric asymmetries during ingress and egress, we can derive clear connections between these variations and the underlying asymmetries of the planetary limbs. Additionally, this approach enables us to investigate differences between the limbs slightly offset from the terminator on the dayside and the nightside. We applied this method to JWST's NIRSpec/G395H observations of the hot Saturn exoplanet WASP-39 b. Our analysis suggests a higher abundance of CO2 on the evening limb compared to the morning limb and indicates a greater probability of SO2 on the limb slightly offset from the terminator on the dayside relative to the nightside. These findings highlight the potential of our method to enhance the understanding of photochemical processes in exoplanetary atmospheres.
title Probing 2D Asymmetries of an Exoplanet Atmosphere from Chromatic Transit Variation
topic Earth and Planetary Astrophysics
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2503.08988