Spectroscopically resolved partial phase curve of the rapid heating and cooling of the highly-eccentric Hot Jupiter HAT-P-2b with WFC3

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Main Authors: Jacobs, Bob, Désert, Jean-Michel, Lewis, Nikole, Challener, Ryan C., Mayorga, L. C., de Beurs, Zoë, Parmentier, Vivien, Stevenson, Kevin B., de Wit, Julien, Barat, Saugata, Fortney, Jonathan, Kataria, Tiffany, Line, Michael
Format: Preprint
Published: 2024
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author Jacobs, Bob
Désert, Jean-Michel
Lewis, Nikole
Challener, Ryan C.
Mayorga, L. C.
de Beurs, Zoë
Parmentier, Vivien
Stevenson, Kevin B.
de Wit, Julien
Barat, Saugata
Fortney, Jonathan
Kataria, Tiffany
Line, Michael
author_facet Jacobs, Bob
Désert, Jean-Michel
Lewis, Nikole
Challener, Ryan C.
Mayorga, L. C.
de Beurs, Zoë
Parmentier, Vivien
Stevenson, Kevin B.
de Wit, Julien
Barat, Saugata
Fortney, Jonathan
Kataria, Tiffany
Line, Michael
contents The extreme environments of transiting close-in exoplanets in highly-eccentric orbits are ideal for testing exo-climate physics. Spectroscopically resolved phase curves not only allow for the characterization of their thermal response to irradiation changes but also unveil phase-dependent atmospheric chemistry and dynamics. We observed a partial phase curve of the highly-eccentric close-in giant planet HAT-P-2b ($e=0.51,M=9M_{\rm{Jup}}$) with the Wide Field Camera 3 aboard the Hubble Space Telescope. Using these data, we updated the planet's orbital parameters and radius, and retrieved high-frequency pulsations consistent with the planet-induced pulsations reported in Spitzer data. We found that the peak in planetary flux occurred at $6.7\pm0.6$ hr after periastron, with a heating and cooling timescales of $9.0^{+3.5}_{-2.1}$ hr, and $3.6^{+0.7}_{-0.6}$ hr, respectively. We compare the light-curve to various 1-dimensional and 3-dimensional forward models, varying the planet's chemical composition. The strong contrast in flux increase and decrease timescales before and after periapse indicates an opacity term that emerges during the planet's heating phase, potentially due to more H$^{-}$ than expected from chemical equilibrium models. The phase-resolved spectra are largely featureless, that we interpret as indicative an inhomogeneous dayside. However, we identified an anomalously high flux in the spectroscopic bin coinciding with the hydrogen Paschen $β$ line and that is likely connected to the planet's orbit. We interpret this as due to shock heating of the upper atmosphere given the short timescale involved, or evidence for other star-planet interactions.
format Preprint
id arxiv_https___arxiv_org_abs_2410_11643
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Spectroscopically resolved partial phase curve of the rapid heating and cooling of the highly-eccentric Hot Jupiter HAT-P-2b with WFC3
Jacobs, Bob
Désert, Jean-Michel
Lewis, Nikole
Challener, Ryan C.
Mayorga, L. C.
de Beurs, Zoë
Parmentier, Vivien
Stevenson, Kevin B.
de Wit, Julien
Barat, Saugata
Fortney, Jonathan
Kataria, Tiffany
Line, Michael
Earth and Planetary Astrophysics
The extreme environments of transiting close-in exoplanets in highly-eccentric orbits are ideal for testing exo-climate physics. Spectroscopically resolved phase curves not only allow for the characterization of their thermal response to irradiation changes but also unveil phase-dependent atmospheric chemistry and dynamics. We observed a partial phase curve of the highly-eccentric close-in giant planet HAT-P-2b ($e=0.51,M=9M_{\rm{Jup}}$) with the Wide Field Camera 3 aboard the Hubble Space Telescope. Using these data, we updated the planet's orbital parameters and radius, and retrieved high-frequency pulsations consistent with the planet-induced pulsations reported in Spitzer data. We found that the peak in planetary flux occurred at $6.7\pm0.6$ hr after periastron, with a heating and cooling timescales of $9.0^{+3.5}_{-2.1}$ hr, and $3.6^{+0.7}_{-0.6}$ hr, respectively. We compare the light-curve to various 1-dimensional and 3-dimensional forward models, varying the planet's chemical composition. The strong contrast in flux increase and decrease timescales before and after periapse indicates an opacity term that emerges during the planet's heating phase, potentially due to more H$^{-}$ than expected from chemical equilibrium models. The phase-resolved spectra are largely featureless, that we interpret as indicative an inhomogeneous dayside. However, we identified an anomalously high flux in the spectroscopic bin coinciding with the hydrogen Paschen $β$ line and that is likely connected to the planet's orbit. We interpret this as due to shock heating of the upper atmosphere given the short timescale involved, or evidence for other star-planet interactions.
title Spectroscopically resolved partial phase curve of the rapid heating and cooling of the highly-eccentric Hot Jupiter HAT-P-2b with WFC3
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2410.11643