The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy

Peter Gao; Anjali A. A. Piette; Maria E. Steinrueck; Matthew C. Nixon; Michael Zhang; Eliza M.-R. Kempton; Jacob L. Bean; Emily Rauscher; Vivien Parmentier; Natasha E. Batalha; Arjun B. Savel; Kenneth E. Arnold; Michael T. Roman; Isaac Malsky; Jake Taylor

doi:10.3847/1538-4357/acd16f

The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy

Peter Gao, Anjali A. A. Piette, Maria E. Steinrueck, Matthew C. Nixon, Michael Zhang, Eliza M.-R. Kempton, Jacob L. Bean, Emily Rauscher, Vivien Parmentier, Natasha E. Batalha, Arjun B. Savel, Kenneth E. Arnold, Michael T. Roman, Isaac Malsky, Jake Taylor

Physics and Astronomy

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Abstract

The near-infrared transmission spectrum of the warm sub-Neptune exoplanet GJ 1214 b has been observed to be flat and featureless, implying a high metallicity atmosphere with abundant aerosols. Recent JWST MIRI Low Resolution Spectrometer observations of a phase curve of GJ 1214 b showed that its transmission spectrum is flat out into the mid-infrared. In this paper, we use the combined near- and mid-infrared transmission spectrum of GJ 1214 b to constrain its atmospheric composition and aerosol properties. We generate a grid of photochemical haze models using an aerosol microphysics code for a number of background atmospheres spanning metallicities from 100 to 1000× solar, as well as a steam atmosphere scenario. The flatness of the combined data set largely rules out atmospheric metallicities ≤300× solar due to their large corresponding molecular feature amplitudes, preferring values ≥1000× solar and column haze production rates ≥10^-10 g cm^-2s^-1. The steam atmosphere scenario with similarly high haze production rates also exhibits sufficiently small molecular features to be consistent with the transmission spectrum. These compositions imply that atmospheric mean molecular weights ≥15 g mol^-1 are needed to fit the data. Our results suggest that haze production is highly efficient on GJ 1214 b and could involve non-hydrocarbon, non-nitrogen haze precursors. Further characterization of GJ 1214 b's atmosphere would likely require multiple transits and eclipses using JWST across the near- and mid-infrared, potentially complemented by ground-based high-resolution transmission spectroscopy.

Original language	English
Article number	96
Number of pages	16
Journal	The Astrophysical Journal
Volume	951
Issue number	2
Early online date	5 Jul 2023
DOIs	https://doi.org/10.3847/1538-4357/acd16f
Publication status	Published - 10 Jul 2023

Bibliographical note

Acknowledgments:
We thank H. Zhang, W. Z. Gao, and S. Z. Gao for their loving support during the writing of this paper. This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #1803. Support for this program was provided by NASA through a grant from the Space Telescope Science Institute.

Facilities: JWST(MIRI) - James Webb Space Telescope, HST(WFC3) - Hubble Space Telescope satellite, Spitzer - .

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Gao, P., Piette, A. A. A., Steinrueck, M. E., Nixon, M. C., Zhang, M., Kempton, E. M.-R., Bean, J. L., Rauscher, E., Parmentier, V., Batalha, N. E., Savel, A. B., Arnold, K. E., Roman, M. T., Malsky, I., & Taylor, J. (2023). The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy. The Astrophysical Journal, 951(2), Article 96. https://doi.org/10.3847/1538-4357/acd16f

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title = "The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy",

abstract = "The near-infrared transmission spectrum of the warm sub-Neptune exoplanet GJ 1214 b has been observed to be flat and featureless, implying a high metallicity atmosphere with abundant aerosols. Recent JWST MIRI Low Resolution Spectrometer observations of a phase curve of GJ 1214 b showed that its transmission spectrum is flat out into the mid-infrared. In this paper, we use the combined near- and mid-infrared transmission spectrum of GJ 1214 b to constrain its atmospheric composition and aerosol properties. We generate a grid of photochemical haze models using an aerosol microphysics code for a number of background atmospheres spanning metallicities from 100 to 1000× solar, as well as a steam atmosphere scenario. The flatness of the combined data set largely rules out atmospheric metallicities ≤300× solar due to their large corresponding molecular feature amplitudes, preferring values ≥1000× solar and column haze production rates ≥10-10 g cm-2 s-1. The steam atmosphere scenario with similarly high haze production rates also exhibits sufficiently small molecular features to be consistent with the transmission spectrum. These compositions imply that atmospheric mean molecular weights ≥15 g mol-1 are needed to fit the data. Our results suggest that haze production is highly efficient on GJ 1214 b and could involve non-hydrocarbon, non-nitrogen haze precursors. Further characterization of GJ 1214 b's atmosphere would likely require multiple transits and eclipses using JWST across the near- and mid-infrared, potentially complemented by ground-based high-resolution transmission spectroscopy.",

author = "Peter Gao and Piette, {Anjali A. A.} and Steinrueck, {Maria E.} and Nixon, {Matthew C.} and Michael Zhang and Kempton, {Eliza M.-R.} and Bean, {Jacob L.} and Emily Rauscher and Vivien Parmentier and Batalha, {Natasha E.} and Savel, {Arjun B.} and Arnold, {Kenneth E.} and Roman, {Michael T.} and Isaac Malsky and Jake Taylor",

note = "Acknowledgments: We thank H. Zhang, W. Z. Gao, and S. Z. Gao for their loving support during the writing of this paper. This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #1803. Support for this program was provided by NASA through a grant from the Space Telescope Science Institute. Facilities: JWST(MIRI) - James Webb Space Telescope, HST(WFC3) - Hubble Space Telescope satellite, Spitzer - .",

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doi = "10.3847/1538-4357/acd16f",

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Gao, P, Piette, AAA, Steinrueck, ME, Nixon, MC, Zhang, M, Kempton, EM-R, Bean, JL, Rauscher, E, Parmentier, V, Batalha, NE, Savel, AB, Arnold, KE, Roman, MT, Malsky, I & Taylor, J 2023, 'The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy', The Astrophysical Journal, vol. 951, no. 2, 96. https://doi.org/10.3847/1538-4357/acd16f

TY - JOUR

T1 - The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy

AU - Gao, Peter

AU - Piette, Anjali A. A.

AU - Steinrueck, Maria E.

AU - Nixon, Matthew C.

AU - Zhang, Michael

AU - Kempton, Eliza M.-R.

AU - Bean, Jacob L.

AU - Rauscher, Emily

AU - Parmentier, Vivien

AU - Batalha, Natasha E.

AU - Savel, Arjun B.

AU - Arnold, Kenneth E.

AU - Roman, Michael T.

AU - Malsky, Isaac

AU - Taylor, Jake

N1 - Acknowledgments: We thank H. Zhang, W. Z. Gao, and S. Z. Gao for their loving support during the writing of this paper. This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #1803. Support for this program was provided by NASA through a grant from the Space Telescope Science Institute. Facilities: JWST(MIRI) - James Webb Space Telescope, HST(WFC3) - Hubble Space Telescope satellite, Spitzer - .

PY - 2023/7/10

Y1 - 2023/7/10

N2 - The near-infrared transmission spectrum of the warm sub-Neptune exoplanet GJ 1214 b has been observed to be flat and featureless, implying a high metallicity atmosphere with abundant aerosols. Recent JWST MIRI Low Resolution Spectrometer observations of a phase curve of GJ 1214 b showed that its transmission spectrum is flat out into the mid-infrared. In this paper, we use the combined near- and mid-infrared transmission spectrum of GJ 1214 b to constrain its atmospheric composition and aerosol properties. We generate a grid of photochemical haze models using an aerosol microphysics code for a number of background atmospheres spanning metallicities from 100 to 1000× solar, as well as a steam atmosphere scenario. The flatness of the combined data set largely rules out atmospheric metallicities ≤300× solar due to their large corresponding molecular feature amplitudes, preferring values ≥1000× solar and column haze production rates ≥10-10 g cm-2 s-1. The steam atmosphere scenario with similarly high haze production rates also exhibits sufficiently small molecular features to be consistent with the transmission spectrum. These compositions imply that atmospheric mean molecular weights ≥15 g mol-1 are needed to fit the data. Our results suggest that haze production is highly efficient on GJ 1214 b and could involve non-hydrocarbon, non-nitrogen haze precursors. Further characterization of GJ 1214 b's atmosphere would likely require multiple transits and eclipses using JWST across the near- and mid-infrared, potentially complemented by ground-based high-resolution transmission spectroscopy.

AB - The near-infrared transmission spectrum of the warm sub-Neptune exoplanet GJ 1214 b has been observed to be flat and featureless, implying a high metallicity atmosphere with abundant aerosols. Recent JWST MIRI Low Resolution Spectrometer observations of a phase curve of GJ 1214 b showed that its transmission spectrum is flat out into the mid-infrared. In this paper, we use the combined near- and mid-infrared transmission spectrum of GJ 1214 b to constrain its atmospheric composition and aerosol properties. We generate a grid of photochemical haze models using an aerosol microphysics code for a number of background atmospheres spanning metallicities from 100 to 1000× solar, as well as a steam atmosphere scenario. The flatness of the combined data set largely rules out atmospheric metallicities ≤300× solar due to their large corresponding molecular feature amplitudes, preferring values ≥1000× solar and column haze production rates ≥10-10 g cm-2 s-1. The steam atmosphere scenario with similarly high haze production rates also exhibits sufficiently small molecular features to be consistent with the transmission spectrum. These compositions imply that atmospheric mean molecular weights ≥15 g mol-1 are needed to fit the data. Our results suggest that haze production is highly efficient on GJ 1214 b and could involve non-hydrocarbon, non-nitrogen haze precursors. Further characterization of GJ 1214 b's atmosphere would likely require multiple transits and eclipses using JWST across the near- and mid-infrared, potentially complemented by ground-based high-resolution transmission spectroscopy.

U2 - 10.3847/1538-4357/acd16f

DO - 10.3847/1538-4357/acd16f

M3 - Article

SN - 0004-637X

VL - 951

JO - The Astrophysical Journal

JF - The Astrophysical Journal

IS - 2

M1 - 96

ER -

The Hazy and Metal-rich Atmosphere of GJ 1214 b Constrained by Near- and Mid-infrared Transmission Spectroscopy

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