A Carbon-rich Atmosphere on a Windy Pulsar Planet

Michael Zhang; Maya Beleznay; Timothy D. Brandt; Roger W. Romani; Peter Gao; Hayley Beltz; Matthew Bailes; Matthew C. Nixon; Jacob L. Bean; Thaddeus D. Komacek; Brandon P. Coy; Guangwei Fu; Rafael Luque; Daniel J. Reardon; Emma Carli; Ryan M. Shannon; Jonathan J. Fortney; Anjali A. A. Piette; M. Coleman Miller; Jean-Michel Desert

doi:10.3847/2041-8213/ae157c

A Carbon-rich Atmosphere on a Windy Pulsar Planet

Michael Zhang^*
, Maya Beleznay
, Timothy D. Brandt
, Roger W. Romani
, Peter Gao
, Hayley Beltz
, Matthew Bailes
, Matthew C. Nixon
, Jacob L. Bean
, Thaddeus D. Komacek
, Brandon P. Coy
, Guangwei Fu
, Rafael Luque
, Daniel J. Reardon
, Emma Carli
, Ryan M. Shannon
, Jonathan J. Fortney
, Anjali A. A. Piette
, M. Coleman Miller
, Jean-Michel Desert

^*Corresponding author for this work

Physics and Astronomy

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

Abstract

A handful of enigmatic Jupiter-mass objects have been discovered orbiting pulsars. One such object, PSR J2322–2650b, uniquely resembles a hot-Jupiter exoplanet, due to its minimum density of 1.8 g cm⁻³ and its ∼1900 K equilibrium temperature. We use JWST to observe PSR J2322–2650b’s emission spectrum across an entire orbit. In stark contrast to every known exoplanet orbiting a main-sequence star, we find an atmosphere rich in molecular carbon (C₃, C₂) with strong westward winds. Our observations open up new exoplanetary chemical (ultrahigh C/O and C/N ratios of >100 and >10,000, respectively) and dynamical regimes (ultrafast rotation with external irradiation) to observational study. The extreme carbon enrichment poses a severe challenge to the current understanding of “black-widow” companions, which were expected to consist of a wider range of elements due to their origins as stripped stellar cores.

Original language	English
Article number	L64
Number of pages	15
Journal	Astrophysical Journal Letters
Volume	995
Issue number	2
Early online date	16 Dec 2025
DOIs	https://doi.org/10.3847/2041-8213/ae157c
Publication status	Published - 20 Dec 2025

Keywords

Carbon planets
High energy astrophysics
Pulsar planets
Stellar atmospheres
Hot Jupiters

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ZhangM2025CarbonFinal published version, 4.23 MBLicence: Creative Commons: Attribution (CC BY)

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A carbon-rich atmosphere on a windy pulsar planet
Zhang, M., Beleznay, M., Brandt, T. D., Romani, R. W., Gao, P., Beltz, H., Bailes, M., Nixon, M. C., Bean, J. L., Komacek, T. D., Coy, B. P., Fu, G., Luque, R., Reardon, D. J., Carli, E., Shannon, R. M., Fortney, J. J., Piette, A. A. A., Miller, M. C. & Desert, J.-M., 4 Sept 2025, arXiv, 22 p.
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Zhang, M., Beleznay, M., Brandt, T. D., Romani, R. W., Gao, P., Beltz, H., Bailes, M., Nixon, M. C., Bean, J. L., Komacek, T. D., Coy, B. P., Fu, G., Luque, R., Reardon, D. J., Carli, E., Shannon, R. M., Fortney, J. J., Piette, A. A. A., Miller, M. C., & Desert, J.-M. (2025). A Carbon-rich Atmosphere on a Windy Pulsar Planet. Astrophysical Journal Letters, 995(2), Article L64. https://doi.org/10.3847/2041-8213/ae157c

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title = "A Carbon-rich Atmosphere on a Windy Pulsar Planet",

abstract = "A handful of enigmatic Jupiter-mass objects have been discovered orbiting pulsars. One such object, PSR J2322–2650b, uniquely resembles a hot-Jupiter exoplanet, due to its minimum density of 1.8 g cm−3 and its ∼1900 K equilibrium temperature. We use JWST to observe PSR J2322–2650b{\textquoteright}s emission spectrum across an entire orbit. In stark contrast to every known exoplanet orbiting a main-sequence star, we find an atmosphere rich in molecular carbon (C3, C2) with strong westward winds. Our observations open up new exoplanetary chemical (ultrahigh C/O and C/N ratios of >100 and >10,000, respectively) and dynamical regimes (ultrafast rotation with external irradiation) to observational study. The extreme carbon enrichment poses a severe challenge to the current understanding of “black-widow” companions, which were expected to consist of a wider range of elements due to their origins as stripped stellar cores.",

keywords = "Carbon planets, High energy astrophysics, Pulsar planets, Stellar atmospheres, Hot Jupiters",

author = "Michael Zhang and Maya Beleznay and Brandt, \{Timothy D.\} and Romani, \{Roger W.\} and Peter Gao and Hayley Beltz and Matthew Bailes and Nixon, \{Matthew C.\} and Bean, \{Jacob L.\} and Komacek, \{Thaddeus D.\} and Coy, \{Brandon P.\} and Guangwei Fu and Rafael Luque and Reardon, \{Daniel J.\} and Emma Carli and Shannon, \{Ryan M.\} and Fortney, \{Jonathan J.\} and Piette, \{Anjali A. A.\} and Miller, \{M. Coleman\} and Jean-Michel Desert",

year = "2025",

month = dec,

day = "20",

doi = "10.3847/2041-8213/ae157c",

language = "English",

volume = "995",

journal = "Astrophysical Journal Letters",

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Zhang, M, Beleznay, M, Brandt, TD, Romani, RW, Gao, P, Beltz, H, Bailes, M, Nixon, MC, Bean, JL, Komacek, TD, Coy, BP, Fu, G, Luque, R, Reardon, DJ, Carli, E, Shannon, RM, Fortney, JJ, Piette, AAA, Miller, MC & Desert, J-M 2025, 'A Carbon-rich Atmosphere on a Windy Pulsar Planet', Astrophysical Journal Letters, vol. 995, no. 2, L64. https://doi.org/10.3847/2041-8213/ae157c

TY - JOUR

T1 - A Carbon-rich Atmosphere on a Windy Pulsar Planet

AU - Zhang, Michael

AU - Beleznay, Maya

AU - Brandt, Timothy D.

AU - Romani, Roger W.

AU - Gao, Peter

AU - Beltz, Hayley

AU - Bailes, Matthew

AU - Nixon, Matthew C.

AU - Bean, Jacob L.

AU - Komacek, Thaddeus D.

AU - Coy, Brandon P.

AU - Fu, Guangwei

AU - Luque, Rafael

AU - Reardon, Daniel J.

AU - Carli, Emma

AU - Shannon, Ryan M.

AU - Fortney, Jonathan J.

AU - Piette, Anjali A. A.

AU - Miller, M. Coleman

AU - Desert, Jean-Michel

PY - 2025/12/20

Y1 - 2025/12/20

N2 - A handful of enigmatic Jupiter-mass objects have been discovered orbiting pulsars. One such object, PSR J2322–2650b, uniquely resembles a hot-Jupiter exoplanet, due to its minimum density of 1.8 g cm−3 and its ∼1900 K equilibrium temperature. We use JWST to observe PSR J2322–2650b’s emission spectrum across an entire orbit. In stark contrast to every known exoplanet orbiting a main-sequence star, we find an atmosphere rich in molecular carbon (C3, C2) with strong westward winds. Our observations open up new exoplanetary chemical (ultrahigh C/O and C/N ratios of >100 and >10,000, respectively) and dynamical regimes (ultrafast rotation with external irradiation) to observational study. The extreme carbon enrichment poses a severe challenge to the current understanding of “black-widow” companions, which were expected to consist of a wider range of elements due to their origins as stripped stellar cores.

AB - A handful of enigmatic Jupiter-mass objects have been discovered orbiting pulsars. One such object, PSR J2322–2650b, uniquely resembles a hot-Jupiter exoplanet, due to its minimum density of 1.8 g cm−3 and its ∼1900 K equilibrium temperature. We use JWST to observe PSR J2322–2650b’s emission spectrum across an entire orbit. In stark contrast to every known exoplanet orbiting a main-sequence star, we find an atmosphere rich in molecular carbon (C3, C2) with strong westward winds. Our observations open up new exoplanetary chemical (ultrahigh C/O and C/N ratios of >100 and >10,000, respectively) and dynamical regimes (ultrafast rotation with external irradiation) to observational study. The extreme carbon enrichment poses a severe challenge to the current understanding of “black-widow” companions, which were expected to consist of a wider range of elements due to their origins as stripped stellar cores.

KW - Carbon planets

KW - High energy astrophysics

KW - Pulsar planets

KW - Stellar atmospheres

KW - Hot Jupiters

U2 - 10.3847/2041-8213/ae157c

DO - 10.3847/2041-8213/ae157c

M3 - Article

SN - 2041-8205

VL - 995

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L64

ER -

A Carbon-rich Atmosphere on a Windy Pulsar Planet

Abstract

Keywords

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A carbon-rich atmosphere on a windy pulsar planet

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