Astrochemistry

The Effects Of The Carbon-to-oxygen Ratio On The Condensate Compositions Around Solar-like Stars

By Keith Cowing
Status Report
astro-ph.EP
August 17, 2024
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The Effects Of The Carbon-to-oxygen Ratio On The Condensate Compositions Around Solar-like Stars
The final C/O ratio, denoted by color, at different distances from the central star and initial C/O ratios. The y-axis is a linear scale of the radii in AUs. The z-axis, or colored contours, is a log scale of the final local C/O ratio for the given simulation’s initial conditions and at the indicated distance from the central star. Black lines help emphasize each change of 106 and the contour line for C/O=1 is represented with a dotted line. The black dot located at C/O=0.501 and R=1 AU represents the location and initial C/O ratio of Earth’s position in the Solar protoplanetary disk. Note that the resolution of these two contour plots is not uniform between the x and y-axis. The resolution is the poorest at the far left, far right, and top. Lastly, note that the resolution of the x-axis is not uniform, see table 1 for the exact initial C/O ratios we explore. (Left) The x-axis is a log scale of the initial C/O ratio spanning all ratios examined. (Right) The x-axis is a linear scale and spans C/O ratios of 0-2.1. The z-axis here is limited from 10−3 -to-103 to better display small changes in the final C/O ratio. The dash-dotted lines in the right plot represent the 10−3 and 103 cutoffs in the z-axis. — astro-ph.EP

The initial stellar carbon-to-oxygen (C/O) ratio can have a large impact on the resulting condensed species present in the protoplanetary disk and, hence, the composition of the bodies and planets that form.

The observed C/O ratios of stars can vary from 0.1-2. We use a sequential dust condensation model to examine the impact of the C/O ratio on the composition of solids around a Solar-like star.

We utilize this model in a focused examination of the impact of varying the initial stellar C/O ratio to isolate the effects of the C/O ratio in the context of Solar-like stars. We describe three different system types in our findings. The Solar system falls into the silicate-dominant, low C/O ratio systems which end at a stellar C/O ratio somewhere between 0.52 and 0.6. At C/O ratios between about 0.6 and 0.9, we have intermediate systems.

Intermediate systems show a decrease in silicates while carbides begin to become significant. Carbide-dominant systems begin around a C/O ratio of 0.9. Carbide-dominant systems exhibit high carbide surface densities at inner radii with comparable levels of carbides and silicates at outer radii.

Our models show that changes between C/O=0.8 and C/O=1 are more significant than previous studies, that carbon can exceed 80% of the condensed mass, and that carbon condensation can be significant at radii up to 6 AU.

Comments: Submitted
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2408.07761 [astro-ph.EP] (or arXiv:2408.07761v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2408.07761
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Submission history
From: Cody Shakespeare
[v1] Wed, 14 Aug 2024 18:26:13 UTC (640 KB)
https://arxiv.org/abs/2408.07761
Astrobiology, Astrochemistry,

Keith Cowing

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) 🖖🏻

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