Abundant Hydrocarbons in the Disk Around a Very-low-mass Star

By Keith Cowing
Status Report
June 21, 2024
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Abundant Hydrocarbons in the Disk Around a Very-low-mass Star
Two scenarios to produce a high C/O ratio in the inner disk. Schematic cross-sections of the disk around a VLMS in the (A) oxygen depletion and (B) carbon enrichment scenarios. The left sides of each panel illustrate the C/O enrichment process, while the right sides show the resulting state of the disk, corresponding to when we observe it. Colored shading indicates elemental abundances of carbon (orange) and oxygen (blue). The two-color arrows pointing towards the VLMS indicate accretion of material onto the star. The grey arrow indicates transport processes. The region between the two vertical dotted lines indicates the region where the carbon in the solids is released into the gas. The brown, blue, and grey blobs indicate unaffected solids, ice covered solids and carbon depleted solids in the disk respectively. — astro-ph.EP

Very low-mass stars (those <0.3 solar masses) host orbiting terrestrial planets more frequently than other types of stars, but the compositions of those planets are largely unknown.

We use mid-infrared spectroscopy with the James Webb Space Telescope to investigate the chemical composition of the planet-forming disk around ISO-ChaI 147, a 0.11 solar-mass star. The inner disk has a carbon-rich chemistry: we identify emission from 13 carbon-bearing molecules including ethane and benzene.

We derive large column densities of hydrocarbons indicating that we probe deep into the disk. The high carbon to oxygen ratio we infer indicates radial transport of material within the disk, which we predict would affect the bulk composition of any planets forming in the disk.

Mid-infrared spectrum of ISO-ChaI 147. The black line is the continuum-subtracted
MIRI spectrum (21). Colors indicate the modelled contributions to the spectrum of different
molecules (labeled, see also the legend) which have been stacked. The estimated gas properties
are listed in Tab. 2. Fig. S1 shows the same spectrum before continuum-subtraction (1 mJy = 10-
29 Wm-2Hz-1). — astro-ph.EP

A. M. Arabhavi, I. Kamp, Th. Henning, E. F. van Dishoeck, V. Christiaens, D. Gasman, A. Perrin, M. Güdel, B. Tabone, J. Kanwar, L. B. F. M. Waters, I. Pascucci, M. Samland, G. Perotti, G. Bettoni, S. L. Grant, P. O. Lagage, T. P. Ray, B. Vandenbussche, O. Absil, I. Argyriou, D. Barrado, A. Boccaletti, J. Bouwman, A. Caratti o Garatti, A. M. Glauser, F. Lahuis, M. Mueller, G. Olofsson, E. Pantin, S. Scheithauer, M. Morales-Calderón, R. Franceschi, H. Jang, N. Pawellek, D. Rodgers-Lee, J. Schreiber, K. Schwarz, M. Temmink, M. Vlasblom, G. Wright, L. Colina, G. Östlin

Comments: Published, 36 pages, 8 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2406.14293 [astro-ph.EP] (or arXiv:2406.14293v1 [astro-ph.EP] for this version)
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Journal reference: Science, Vol 384, Issue 6700, 2024, pp. 1086-1090
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Submission history
From: Aditya Mahadeva Arabhavi
[v1] Thu, 20 Jun 2024 13:20:26 UTC (2,018 KB)
Astrobiology, Astrochemistry,

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻