A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

Eliza M.-R. Kempton; Michael Zhang; Jacob L. Bean; Maria E. Steinrueck; Anjali A. A. Piette; Vivien Parmentier; Isaac Malsky; Michael T. Roman; Emily Rauscher; Peter Gao; Taylor J. Bell; Qiao Xue; Jake Taylor; Arjun B. Savel; Kenneth E. Arnold; Matthew C. Nixon; Kevin B. Stevenson; Megan Mansfield; Sarah Kendrew; Sebastian Zieba; Elsa Ducrot; Achrène Dyrek; Pierre-Olivier Lagage; Keivan G. Stassun; Gregory W. Henry; Travis Barman; Roxana Lupu; Matej Malik; Tiffany Kataria; Jegug Ih; Guangwei Fu; Luis Welbanks; Peter McGill

doi:10.1038/s41586-023-06159-5

A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

Eliza M.-R. Kempton^*, Michael Zhang, Jacob L. Bean, Maria E. Steinrueck, Anjali A. A. Piette, Vivien Parmentier, Isaac Malsky, Michael T. Roman, Emily Rauscher, Peter Gao, Taylor J. Bell, Qiao Xue, Jake Taylor, Arjun B. Savel, Kenneth E. Arnold, Matthew C. Nixon, Kevin B. Stevenson, Megan Mansfield, Sarah Kendrew, Sebastian ZiebaElsa Ducrot, Achrène Dyrek, Pierre-Olivier Lagage, Keivan G. Stassun, Gregory W. Henry, Travis Barman, Roxana Lupu, Matej Malik, Tiffany Kataria, Jegug Ih, Guangwei Fu, Luis Welbanks, Peter McGill

^*Corresponding author for this work

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars₁. Population statistics show that close-in planets in this size range bifurcate into two classes on the basis of their radii^2,3. It is proposed that the group with larger radii (referred to as ‘sub-Neptunes’) is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets⁴. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis^{5,6,7,8,9,10,11,12,13,14}. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet’s atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with the James Webb Space Telescope (JWST) in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show more than 3σ evidence of absorption features, with H₂O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b’s Bond albedo is 0.51 ± 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze.

Original language	English
Pages (from-to)	67–71
Number of pages	5
Journal	Nature
Volume	620
Early online date	10 May 2023
DOIs	https://doi.org/10.1038/s41586-023-06159-5
Publication status	Published - 3 Aug 2023

Bibliographical note

Acknowledgments:
This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. 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 no. NAS 5-03127 for JWST. These observations are associated with programme no. 1803. Support for this programme was provided by NASA through a grant from the Space Telescope Science Institute. This work benefited from the 2022 Exoplanet Summer Program in the Other Worlds Laboratory at the University of California, Santa Cruz, a programme supported by the Heising-Simons Foundation. E.M.R.K. acknowledges funding from the NSF CAREER programme (grant no. 1931736). M.Z. acknowledges support from the 51 Pegasi b Fellowship financed by the Heising-Simons Foundation. M. Mansfield and L.W. acknowledge support provided by NASA through the NASA Hubble Fellowship Program. J.T. acknowledges support from the John Fell Fund and the Candadian Space Agency.

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Kempton, E. M.-R., Zhang, M., Bean, J. L., Steinrueck, M. E., Piette, A. A. A., Parmentier, V., Malsky, I., Roman, M. T., Rauscher, E., Gao, P., Bell, T. J., Xue, Q., Taylor, J., Savel, A. B., Arnold, K. E., Nixon, M. C., Stevenson, K. B., Mansfield, M., Kendrew, S., ... McGill, P. (2023). A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve. Nature, 620, 67–71. https://doi.org/10.1038/s41586-023-06159-5

@article{f74bb49f9f064916bd2428790176b82c,

title = "A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve",

abstract = "There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars1. Population statistics show that close-in planets in this size range bifurcate into two classes on the basis of their radii2,3. It is proposed that the group with larger radii (referred to as {\textquoteleft}sub-Neptunes{\textquoteright}) is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets4. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis5,6,7,8,9,10,11,12,13,14. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet{\textquoteright}s atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with the James Webb Space Telescope (JWST) in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show more than 3σ evidence of absorption features, with H2O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b{\textquoteright}s Bond albedo is 0.51 ± 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze.",

author = "Kempton, {Eliza M.-R.} and Michael Zhang and Bean, {Jacob L.} and Steinrueck, {Maria E.} and Piette, {Anjali A. A.} and Vivien Parmentier and Isaac Malsky and Roman, {Michael T.} and Emily Rauscher and Peter Gao and Bell, {Taylor J.} and Qiao Xue and Jake Taylor and Savel, {Arjun B.} and Arnold, {Kenneth E.} and Nixon, {Matthew C.} and Stevenson, {Kevin B.} and Megan Mansfield and Sarah Kendrew and Sebastian Zieba and Elsa Ducrot and Achr{\`e}ne Dyrek and Pierre-Olivier Lagage and Stassun, {Keivan G.} and Henry, {Gregory W.} and Travis Barman and Roxana Lupu and Matej Malik and Tiffany Kataria and Jegug Ih and Guangwei Fu and Luis Welbanks and Peter McGill",

note = "Acknowledgments: This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. 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 no. NAS 5-03127 for JWST. These observations are associated with programme no. 1803. Support for this programme was provided by NASA through a grant from the Space Telescope Science Institute. This work benefited from the 2022 Exoplanet Summer Program in the Other Worlds Laboratory at the University of California, Santa Cruz, a programme supported by the Heising-Simons Foundation. E.M.R.K. acknowledges funding from the NSF CAREER programme (grant no. 1931736). M.Z. acknowledges support from the 51 Pegasi b Fellowship financed by the Heising-Simons Foundation. M. Mansfield and L.W. acknowledge support provided by NASA through the NASA Hubble Fellowship Program. J.T. acknowledges support from the John Fell Fund and the Candadian Space Agency.",

year = "2023",

month = aug,

day = "3",

doi = "10.1038/s41586-023-06159-5",

language = "English",

volume = "620",

pages = "67–71",

journal = "Nature",

issn = "0028-0836",

publisher = "Nature Publishing Group",

}

Kempton, EM-R, Zhang, M, Bean, JL, Steinrueck, ME, Piette, AAA, Parmentier, V, Malsky, I, Roman, MT, Rauscher, E, Gao, P, Bell, TJ, Xue, Q, Taylor, J, Savel, AB, Arnold, KE, Nixon, MC, Stevenson, KB, Mansfield, M, Kendrew, S, Zieba, S, Ducrot, E, Dyrek, A, Lagage, P-O, Stassun, KG, Henry, GW, Barman, T, Lupu, R, Malik, M, Kataria, T, Ih, J, Fu, G, Welbanks, L & McGill, P 2023, 'A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve', Nature, vol. 620, pp. 67–71. https://doi.org/10.1038/s41586-023-06159-5

TY - JOUR

T1 - A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

AU - Kempton, Eliza M.-R.

AU - Zhang, Michael

AU - Bean, Jacob L.

AU - Steinrueck, Maria E.

AU - Piette, Anjali A. A.

AU - Parmentier, Vivien

AU - Malsky, Isaac

AU - Roman, Michael T.

AU - Rauscher, Emily

AU - Gao, Peter

AU - Bell, Taylor J.

AU - Xue, Qiao

AU - Taylor, Jake

AU - Savel, Arjun B.

AU - Arnold, Kenneth E.

AU - Nixon, Matthew C.

AU - Stevenson, Kevin B.

AU - Mansfield, Megan

AU - Kendrew, Sarah

AU - Zieba, Sebastian

AU - Ducrot, Elsa

AU - Dyrek, Achrène

AU - Lagage, Pierre-Olivier

AU - Stassun, Keivan G.

AU - Henry, Gregory W.

AU - Barman, Travis

AU - Lupu, Roxana

AU - Malik, Matej

AU - Kataria, Tiffany

AU - Ih, Jegug

AU - Fu, Guangwei

AU - Welbanks, Luis

AU - McGill, Peter

N1 - Acknowledgments: This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. 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 no. NAS 5-03127 for JWST. These observations are associated with programme no. 1803. Support for this programme was provided by NASA through a grant from the Space Telescope Science Institute. This work benefited from the 2022 Exoplanet Summer Program in the Other Worlds Laboratory at the University of California, Santa Cruz, a programme supported by the Heising-Simons Foundation. E.M.R.K. acknowledges funding from the NSF CAREER programme (grant no. 1931736). M.Z. acknowledges support from the 51 Pegasi b Fellowship financed by the Heising-Simons Foundation. M. Mansfield and L.W. acknowledge support provided by NASA through the NASA Hubble Fellowship Program. J.T. acknowledges support from the John Fell Fund and the Candadian Space Agency.

PY - 2023/8/3

Y1 - 2023/8/3

N2 - There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars1. Population statistics show that close-in planets in this size range bifurcate into two classes on the basis of their radii2,3. It is proposed that the group with larger radii (referred to as ‘sub-Neptunes’) is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets4. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis5,6,7,8,9,10,11,12,13,14. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet’s atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with the James Webb Space Telescope (JWST) in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show more than 3σ evidence of absorption features, with H2O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b’s Bond albedo is 0.51 ± 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze.

AB - There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars1. Population statistics show that close-in planets in this size range bifurcate into two classes on the basis of their radii2,3. It is proposed that the group with larger radii (referred to as ‘sub-Neptunes’) is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets4. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis5,6,7,8,9,10,11,12,13,14. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet’s atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with the James Webb Space Telescope (JWST) in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show more than 3σ evidence of absorption features, with H2O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b’s Bond albedo is 0.51 ± 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze.

U2 - 10.1038/s41586-023-06159-5

DO - 10.1038/s41586-023-06159-5

M3 - Article

SN - 0028-0836

VL - 620

SP - 67

EP - 71

JO - Nature

JF - Nature

ER -

A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

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