A JWST Study of the Remarkable Oort Cloud Comet C/2017 K2 (PanSTARRS)
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| Format: | Preprint |
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2025
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| _version_ | 1866915263288442880 |
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| author | Woodward, Charles E. Bockelee-Morvan, Dominique Harker, David E. Kelley, Michael S. P. Roth, Nathan X. Wooden, Diane H. Milam, Stefanie N. |
| author_facet | Woodward, Charles E. Bockelee-Morvan, Dominique Harker, David E. Kelley, Michael S. P. Roth, Nathan X. Wooden, Diane H. Milam, Stefanie N. |
| contents | Comets, during their journeys into the inner solar system, deliver volatile gases, organics, and particulates into their comae that provide crucial information for assessing the physico-chemical conditions in the outer disk from which they formed. Here we present observational and modeling results of a JWST NIRSpec and MIRI MRS integral-field-unit (IFU) spatial-spectral study of the inner coma of the Oort Cloud comet C/2017 K2 (PanSTARRS) at a heliocentric distance of 2.35 au. We find the comet is hyperactive (water ice active fraction greater than or equal to 86%), with a nucleus radius of $<$4.2 km, exhibiting strong emission from H$_{2}$O, $^{12}$CO, $^{13}$CO, and CO$_{2}$ as well as CN, H$_2$CO, CH$_3$OH, CH$_4$, C$_2$H$_6$, HCN, NH$_2$, and OH prompt emission. The water ortho-to-para ratio is greater than or equal to 2.75. The modeled dust composition (relative mass fraction of the sub-micron grains) in the coma is dominated by amorphous carbon ($\simeq 25$%), amorphous Mg:Fe olivine ($\simeq 19$%), amorphous Mg:Fe pyroxene ($\simeq 16$%), and Mg-rich crystalline olivine ($\simeq 39$%) and the crystalline mass fraction of the sub-micron grains in the coma is, $f_{cryst} \simeq 0.384 \pm 0.065$. Analysis of residuals in 3 to 8 $μ$m region of the spectral energy distribution strongly suggests the presence of polycyclic aromatic hydrocarbon (PAHs) species in the coma. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_19849 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A JWST Study of the Remarkable Oort Cloud Comet C/2017 K2 (PanSTARRS) Woodward, Charles E. Bockelee-Morvan, Dominique Harker, David E. Kelley, Michael S. P. Roth, Nathan X. Wooden, Diane H. Milam, Stefanie N. Earth and Planetary Astrophysics Instrumentation and Methods for Astrophysics Comets, during their journeys into the inner solar system, deliver volatile gases, organics, and particulates into their comae that provide crucial information for assessing the physico-chemical conditions in the outer disk from which they formed. Here we present observational and modeling results of a JWST NIRSpec and MIRI MRS integral-field-unit (IFU) spatial-spectral study of the inner coma of the Oort Cloud comet C/2017 K2 (PanSTARRS) at a heliocentric distance of 2.35 au. We find the comet is hyperactive (water ice active fraction greater than or equal to 86%), with a nucleus radius of $<$4.2 km, exhibiting strong emission from H$_{2}$O, $^{12}$CO, $^{13}$CO, and CO$_{2}$ as well as CN, H$_2$CO, CH$_3$OH, CH$_4$, C$_2$H$_6$, HCN, NH$_2$, and OH prompt emission. The water ortho-to-para ratio is greater than or equal to 2.75. The modeled dust composition (relative mass fraction of the sub-micron grains) in the coma is dominated by amorphous carbon ($\simeq 25$%), amorphous Mg:Fe olivine ($\simeq 19$%), amorphous Mg:Fe pyroxene ($\simeq 16$%), and Mg-rich crystalline olivine ($\simeq 39$%) and the crystalline mass fraction of the sub-micron grains in the coma is, $f_{cryst} \simeq 0.384 \pm 0.065$. Analysis of residuals in 3 to 8 $μ$m region of the spectral energy distribution strongly suggests the presence of polycyclic aromatic hydrocarbon (PAHs) species in the coma. |
| title | A JWST Study of the Remarkable Oort Cloud Comet C/2017 K2 (PanSTARRS) |
| topic | Earth and Planetary Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2504.19849 |