Efficient early global relaxation of asteroid Vesta
The asteroid Vesta is a differentiated planetesimal from the accretion phase of Solar System formation. Although its present-day shape is dominated by a non-hydrostatic fossil equatorial bulge and two large, mostly unrelaxed impact basins, Vesta may have been able to approach hydrostatic equilibrium...
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| Format: | Article |
| Language: | en_US |
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Elsevier
2017
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| Online Access: | http://hdl.handle.net/1721.1/106596 https://orcid.org/0000-0003-3635-2676 https://orcid.org/0000-0003-2652-8017 |
| _version_ | 1826199970204614656 |
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| author | Fu, Roger Rennan Hager, Bradford H Ermakov, Anton Zuber, Maria |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Fu, Roger Rennan Hager, Bradford H Ermakov, Anton Zuber, Maria |
| author_sort | Fu, Roger Rennan |
| collection | MIT |
| description | The asteroid Vesta is a differentiated planetesimal from the accretion phase of Solar System formation. Although its present-day shape is dominated by a non-hydrostatic fossil equatorial bulge and two large, mostly unrelaxed impact basins, Vesta may have been able to approach hydrostatic equilibrium during a brief early period of intense interior heating. We use a finite element viscoplastic flow model coupled to a 1D conductive cooling model to calculate the expected rate of relaxation throughout Vesta’s early history. We find that, given sufficient non-hydrostaticity, the early elastic lithosphere of Vesta experienced extensive brittle failure due to self-gravity, thereby allowing relaxation to a more hydrostatic figure. Soon after its accretion, Vesta reached a closely hydrostatic figure with <2 km non-hydrostatic topography at degree-2, which, once scaled, is similar to the maximum disequilibrium of the hydrostatic asteroid Ceres. Vesta was able to support the modern observed amplitude of non-hydrostatic topography only >40–200 My after formation, depending on the assumed depth of megaregolith. The Veneneia and Rheasilvia giant impacts, which generated most non-hydrostatic topography, must have therefore occurred >40–200 My after formation. Based on crater retention ages, topography, and relation to known impact generated features, we identify a large region in the northern hemisphere that likely represents relic hydrostatic terrain from early Vesta. The long-wavelength figure of this terrain suggests that, before the two late giant impacts, Vesta had a rotation period of 5.02 h (6.3% faster than present) while its spin axis was offset by 3.0 ° from that of the present. The evolution of Vesta’s figure shows that the hydrostaticity of small bodies depends strongly on its age and specific impact history and that a single body may embody both hydrostatic and non-hydrostatic terrains and epochs. |
| first_indexed | 2024-09-23T11:28:42Z |
| format | Article |
| id | mit-1721.1/106596 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:28:42Z |
| publishDate | 2017 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | mit-1721.1/1065962022-09-27T19:50:06Z Efficient early global relaxation of asteroid Vesta Fu, Roger Rennan Hager, Bradford H Ermakov, Anton Zuber, Maria Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Hager, Bradford H. Fu, Roger Rennan Hager, Bradford H Ermakov, Anton Zuber, Maria The asteroid Vesta is a differentiated planetesimal from the accretion phase of Solar System formation. Although its present-day shape is dominated by a non-hydrostatic fossil equatorial bulge and two large, mostly unrelaxed impact basins, Vesta may have been able to approach hydrostatic equilibrium during a brief early period of intense interior heating. We use a finite element viscoplastic flow model coupled to a 1D conductive cooling model to calculate the expected rate of relaxation throughout Vesta’s early history. We find that, given sufficient non-hydrostaticity, the early elastic lithosphere of Vesta experienced extensive brittle failure due to self-gravity, thereby allowing relaxation to a more hydrostatic figure. Soon after its accretion, Vesta reached a closely hydrostatic figure with <2 km non-hydrostatic topography at degree-2, which, once scaled, is similar to the maximum disequilibrium of the hydrostatic asteroid Ceres. Vesta was able to support the modern observed amplitude of non-hydrostatic topography only >40–200 My after formation, depending on the assumed depth of megaregolith. The Veneneia and Rheasilvia giant impacts, which generated most non-hydrostatic topography, must have therefore occurred >40–200 My after formation. Based on crater retention ages, topography, and relation to known impact generated features, we identify a large region in the northern hemisphere that likely represents relic hydrostatic terrain from early Vesta. The long-wavelength figure of this terrain suggests that, before the two late giant impacts, Vesta had a rotation period of 5.02 h (6.3% faster than present) while its spin axis was offset by 3.0 ° from that of the present. The evolution of Vesta’s figure shows that the hydrostaticity of small bodies depends strongly on its age and specific impact history and that a single body may embody both hydrostatic and non-hydrostatic terrains and epochs. National Science Foundation (U.S.). Graduate Research Fellowship Program 2017-01-24T16:04:07Z 2017-01-24T16:04:07Z 2014-02 Article http://purl.org/eprint/type/JournalArticle 0019-1035 1090-2643 http://hdl.handle.net/1721.1/106596 Fu, Roger R. et al. “Efficient Early Global Relaxation of Asteroid Vesta.” Icarus 240 (2014): 133–145. https://orcid.org/0000-0003-3635-2676 https://orcid.org/0000-0003-2652-8017 en_US http://dx.doi.org/10.1016/j.icarus.2014.01.023 Icarus Creative Commons Attribution-NonCommercial-NoDerivs License http://creativecommons.org/licenses/by-nc-nd/4.0/ application/pdf Elsevier Prof. Hager |
| spellingShingle | Fu, Roger Rennan Hager, Bradford H Ermakov, Anton Zuber, Maria Efficient early global relaxation of asteroid Vesta |
| title | Efficient early global relaxation of asteroid Vesta |
| title_full | Efficient early global relaxation of asteroid Vesta |
| title_fullStr | Efficient early global relaxation of asteroid Vesta |
| title_full_unstemmed | Efficient early global relaxation of asteroid Vesta |
| title_short | Efficient early global relaxation of asteroid Vesta |
| title_sort | efficient early global relaxation of asteroid vesta |
| url | http://hdl.handle.net/1721.1/106596 https://orcid.org/0000-0003-3635-2676 https://orcid.org/0000-0003-2652-8017 |
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