Implications of evaporative cooling by H$_2$ for 1I/`Oumuamua
2023
Online
report
Zugriff:
The first interstellar object observed in our solar system, 1I/`Oumuamua, exhibited several peculiar properties, including extreme elongation and non-gravitational acceleration. Bergner and Seligman (hereafter BS23) proposed that evaporation of trapped H$_2$ created by cosmic rays (CRs) can explain the non-gravitational acceleration. However, their modeling of the thermal structure of 1I/`Oumuamua ignored the crucial cooling effect of evaporating H$_2$. By taking into account the cooling by H$_2$ evaporation, we show that the surface temperature of H$_2$-water ice is a factor of 9 lower than the case without evaporative cooling. As a result, the thermal speed of outgassing H$_2$ is decreased by a factor of 3. Our one-dimensional thermal modeling that takes into account evaporative cooling for two chosen values of thermal conductivity of $\kappa=0.01$ and $0.1$ WK$^{-1}$m$^{-1}$ shows that the water ice volume available for H$_2$ sublimation at $T>30$ K would be reduced by a factor of 9 and 5 compared to the results of BS23, not enabling enough hydrogen to propel 1I/`Oumuamua.
Comment: 6 pages, 2 figure; Accepted for publication, Astrophysical Journal Letters
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Implications of evaporative cooling by H$_2$ for 1I/`Oumuamua
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Autor/in / Beteiligte Person: | Hoang, Thiem ; Loeb, Abraham |
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Veröffentlichung: | 2023 |
Medientyp: | report |
DOI: | 10.3847/2041-8213/acdf57 |
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