The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase
We present a JWST MIRI/MRS spectrum of the inner disk of WISE J044634.16–262756.1B (hereafter J0446B), an old (∼34 Myr) M4.5 star but with hints of ongoing accretion. The spectrum is molecule-rich and dominated by hydrocarbons. We detect 14 molecular species (H _2 , CH _3 , CH _4 , C _2 H _2 , ^13 C...
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2025-01-01
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| author | Feng Long Ilaria Pascucci Adrien Houge Andrea Banzatti Klaus M. Pontoppidan Joan Najita Sebastiaan Krijt Chengyan Xie Joe Williams Gregory J. Herczeg Sean M. Andrews Edwin Bergin Geoffrey A. Blake María José Colmenares Daniel Harsono Carlos E. Romero-Mirza Rixin Li Cicero X. Lu Paola Pinilla David J. Wilner Miguel Vioque Ke Zhang the JDISCS collaboration |
| author_facet | Feng Long Ilaria Pascucci Adrien Houge Andrea Banzatti Klaus M. Pontoppidan Joan Najita Sebastiaan Krijt Chengyan Xie Joe Williams Gregory J. Herczeg Sean M. Andrews Edwin Bergin Geoffrey A. Blake María José Colmenares Daniel Harsono Carlos E. Romero-Mirza Rixin Li Cicero X. Lu Paola Pinilla David J. Wilner Miguel Vioque Ke Zhang the JDISCS collaboration |
| author_sort | Feng Long |
| collection | DOAJ |
| description | We present a JWST MIRI/MRS spectrum of the inner disk of WISE J044634.16–262756.1B (hereafter J0446B), an old (∼34 Myr) M4.5 star but with hints of ongoing accretion. The spectrum is molecule-rich and dominated by hydrocarbons. We detect 14 molecular species (H _2 , CH _3 , CH _4 , C _2 H _2 , ^13 CCH _2 , C _2 H _4 , C _2 H _6 , C _3 H _4 , C _4 H _2 , C _6 H _6 , HCN, HC _3 N, CO _2 , and ^13 CO _2 ) and two atomic lines ([Ne ii ] and [Ar ii ]), all observed for the first time in a disk at this age. The detection of spatially unresolved H _2 and Ne gas strongly supports that J0446B hosts a long-lived primordial disk, rather than a debris disk. The marginal H _2 O detection and the high C _2 H _2 /CO _2 column density ratio indicate that the inner disk of J0446B has a very carbon-rich chemistry, with a gas-phase C/O ratio ≳2, consistent with what has been found in most primordial disks around similarly low-mass stars. In the absence of significant outer disk dust substructures, inner disks are expected to first become water-rich due to the rapid inward drift of icy pebbles and evolve into carbon-rich as outer disk gas flows inward on longer timescales. The faint millimeter emission in such low-mass star disks implies that they may have depleted their outer icy pebble reservoir early and already passed the water-rich phase. Models with pebble drift and volatile transport suggest that maintaining a carbon-rich chemistry for tens of Myr likely requires a slowly evolving disk with α -viscosity ≲10 ^−4 . This study represents the first detailed characterization of disk gas at ∼30 Myr, strongly motivating further studies into the final stages of disk evolution. |
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| publishDate | 2025-01-01 |
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| spelling | doaj-art-e59be1b06aac4e5799103baba6e7ee472025-08-20T02:09:05ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019782L3010.3847/2041-8213/ad99d2The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich PhaseFeng Long0https://orcid.org/0000-0002-7607-719XIlaria Pascucci1https://orcid.org/0000-0001-7962-1683Adrien Houge2https://orcid.org/0000-0001-8790-9011Andrea Banzatti3https://orcid.org/0000-0003-4335-0900Klaus M. Pontoppidan4https://orcid.org/0000-0001-7552-1562Joan Najita5https://orcid.org/0000-0002-5758-150XSebastiaan Krijt6https://orcid.org/0000-0002-3291-6887Chengyan Xie7https://orcid.org/0000-0001-8184-5547Joe Williams8https://orcid.org/0009-0008-8176-1974Gregory J. Herczeg9https://orcid.org/0000-0002-7154-6065Sean M. Andrews10https://orcid.org/0000-0003-2253-2270Edwin Bergin11https://orcid.org/0000-0003-4179-6394Geoffrey A. Blake12https://orcid.org/0000-0003-0787-1610María José Colmenares13https://orcid.org/0000-0002-5296-6232Daniel Harsono14https://orcid.org/0000-0001-6307-4195Carlos E. Romero-Mirza15https://orcid.org/0000-0001-7152-9794Rixin Li16https://orcid.org/0000-0001-9222-4367Cicero X. Lu17https://orcid.org/0000-0001-9352-0248Paola Pinilla18https://orcid.org/0000-0001-8764-1780David J. Wilner19https://orcid.org/0000-0003-1526-7587Miguel Vioque20https://orcid.org/0000-0002-4147-3846Ke Zhang21https://orcid.org/0000-0002-0661-7517the JDISCS collaborationLunar and Planetary Laboratory, University of Arizona , Tucson, AZ 85721, USA ; fenglong@arizona.eduLunar and Planetary Laboratory, University of Arizona , Tucson, AZ 85721, USA ; fenglong@arizona.eduCenter for Star and Planet Formation, GLOBE Institute, University of Copenhagen , Øster Voldgade 5-7, DK-1350 Copenhagen, DenmarkDepartment of Physics, Texas State University , 749 North Comanche Street, San Marcos, TX 78666, USAJet Propulsion Laboratory, California Institute of Technology , 4800 Oak Grove Drive, Pasadena, CA 91109, USANSF's NOIRLab , 950 North Cherry Avenue, Tucson, AZ 85719, USASchool of Physics and Astronomy, University of Exeter , Stocker Road, Exeter EX4 4QL, UKLunar and Planetary Laboratory, University of Arizona , Tucson, AZ 85721, USA ; fenglong@arizona.eduSchool of Physics and Astronomy, University of Exeter , Stocker Road, Exeter EX4 4QL, UKKavli Institute for Astronomy and Astrophysics, Peking University , Beijing 100871, People’s Republic of China; Department of Astronomy, Peking University , Beijing 100871, People’s Republic of ChinaCenter for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USADepartment of Astronomy, University of Michigan , Ann Arbor, MI 48109, USADivision of Geological & Planetary Sciences, MC 150-21, California Institute of Technology , Pasadena, CA 91125, USADepartment of Astronomy, University of Michigan , Ann Arbor, MI 48109, USAInstitute of Astronomy, Department of Physics, National Tsing Hua University , Hsinchu, TaiwanCenter for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USADepartment of Astronomy, Theoretical Astrophysics Center, and Center for Integrative Planetary Science, University of California Berkeley , Berkeley, CA 94720-3411, USAGemini Observatory/NSF's NOIRLab , 670 North A’ohoku Place, Hilo, HI 96720, USAMullard Space Science Laboratory, University College London , Holmbury St Mary, Dorking, Surrey RH5 6NT, UKCenter for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAEuropean Southern Observatory , Karl-Schwarzschild-Str. 2, 85748, Garching bei Munchen, GermanyDepartment of Astronomy, University of Wisconsin–Madison , Madison, WI 53706, USAWe present a JWST MIRI/MRS spectrum of the inner disk of WISE J044634.16–262756.1B (hereafter J0446B), an old (∼34 Myr) M4.5 star but with hints of ongoing accretion. The spectrum is molecule-rich and dominated by hydrocarbons. We detect 14 molecular species (H _2 , CH _3 , CH _4 , C _2 H _2 , ^13 CCH _2 , C _2 H _4 , C _2 H _6 , C _3 H _4 , C _4 H _2 , C _6 H _6 , HCN, HC _3 N, CO _2 , and ^13 CO _2 ) and two atomic lines ([Ne ii ] and [Ar ii ]), all observed for the first time in a disk at this age. The detection of spatially unresolved H _2 and Ne gas strongly supports that J0446B hosts a long-lived primordial disk, rather than a debris disk. The marginal H _2 O detection and the high C _2 H _2 /CO _2 column density ratio indicate that the inner disk of J0446B has a very carbon-rich chemistry, with a gas-phase C/O ratio ≳2, consistent with what has been found in most primordial disks around similarly low-mass stars. In the absence of significant outer disk dust substructures, inner disks are expected to first become water-rich due to the rapid inward drift of icy pebbles and evolve into carbon-rich as outer disk gas flows inward on longer timescales. The faint millimeter emission in such low-mass star disks implies that they may have depleted their outer icy pebble reservoir early and already passed the water-rich phase. Models with pebble drift and volatile transport suggest that maintaining a carbon-rich chemistry for tens of Myr likely requires a slowly evolving disk with α -viscosity ≲10 ^−4 . This study represents the first detailed characterization of disk gas at ∼30 Myr, strongly motivating further studies into the final stages of disk evolution.https://doi.org/10.3847/2041-8213/ad99d2Protoplanetary disksAstrochemistryInfrared astronomyCircumstellar disks |
| spellingShingle | Feng Long Ilaria Pascucci Adrien Houge Andrea Banzatti Klaus M. Pontoppidan Joan Najita Sebastiaan Krijt Chengyan Xie Joe Williams Gregory J. Herczeg Sean M. Andrews Edwin Bergin Geoffrey A. Blake María José Colmenares Daniel Harsono Carlos E. Romero-Mirza Rixin Li Cicero X. Lu Paola Pinilla David J. Wilner Miguel Vioque Ke Zhang the JDISCS collaboration The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase The Astrophysical Journal Letters Protoplanetary disks Astrochemistry Infrared astronomy Circumstellar disks |
| title | The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase |
| title_full | The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase |
| title_fullStr | The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase |
| title_full_unstemmed | The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase |
| title_short | The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase |
| title_sort | first jwst view of a 30 myr old protoplanetary disk reveals a late stage carbon rich phase |
| topic | Protoplanetary disks Astrochemistry Infrared astronomy Circumstellar disks |
| url | https://doi.org/10.3847/2041-8213/ad99d2 |
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