Detection of Hydrocarbons in the Disk around an Actively Accreting Planetary-mass Object

Detection of Hydrocarbons in the Disk around an Actively Accreting Planetary-mass Object

We present the 0.6–12 μ m spectrum of Cha 1107-7626, a 6–10 Jupiter-mass free-floating object in the ∼2 Myr-old Chamaeleon-I star-forming region, from observations with the NIRSpec and MIRI instruments on board the James Webb Space Telescope. We confirm that Cha 1107-7626 is one of the lowest-mass o...

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Bibliographic Details
Main Authors: Laura Flagg, Aleks Scholz, V. Almendros-Abad, Ray Jayawardhana, Belinda Damian, Koraljka Mužić, Antonella Natta, Paola Pinilla, Leonardo Testi
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Brown dwarfs
Stellar accretion
Protoplanetary disks
Free floating planets
Infrared spectroscopy
Stellar accretion disks
Online Access:https://doi.org/10.3847/1538-4357/add71d
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Summary:We present the 0.6–12 μ m spectrum of Cha 1107-7626, a 6–10 Jupiter-mass free-floating object in the ∼2 Myr-old Chamaeleon-I star-forming region, from observations with the NIRSpec and MIRI instruments on board the James Webb Space Telescope. We confirm that Cha 1107-7626 is one of the lowest-mass objects known to harbor a dusty disk with infrared excess emission at wavelengths beyond 4 μ m. Our NIRSpec data and prior ground-based observations provide strong evidence for ongoing accretion through hydrogen recombination lines. In the mid-infrared spectrum, we detect unambiguously emission lines caused by methane (CH _4 ) and ethylene (C _2 H _4 ) in its circumsubstellar disk. Our findings mean that Cha 1107-7626 is by far the lowest-mass object with hydrocarbons observed in its disk. The spectrum of the disk looks remarkably similar to that of ISO-ChaI 147, a very low-mass star with a carbon-rich disk that is 10–20 times more massive than Cha 1107-7626. The hydrocarbon lines can be accounted for with a model assuming gas temperatures of a few hundred kelvin in the inner disk. The obvious similarities between the spectra of a low-mass star and a planetary-mass object indicate that the conditions in the inner disks can be similar across a wide range of central object masses.
ISSN:1538-4357

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