The $\sim$50-Myr-Old TOI-942c is Likely on an Aligned, Coplanar Orbit and Losing Mass
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| Format: | Preprint |
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2024
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| _version_ | 1866911989362589696 |
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| author | Teng, Huan-Yu Dai, Fei Howard, Andrew W. Isaacson, Howard Rubenzahl, Ryan A. Angelo, Isabel Polanski, Alex S. |
| author_facet | Teng, Huan-Yu Dai, Fei Howard, Andrew W. Isaacson, Howard Rubenzahl, Ryan A. Angelo, Isabel Polanski, Alex S. |
| contents | We report the observation of the transiting planet TOI-942c, a Neptunian planet orbiting a young K-type star approximately 50 Myr years old. Using Keck/HIRES, we observed a partial transit of the planet and detected an associated radial velocity anomaly. By modeling the Rossiter-McLaughlin (RM) effect, we derived a sky-projected obliquity of $\left|λ\right|=24^{+14}_{-14}$ degrees, indicating TOI-942c is in a prograde and likely aligned orbit. Upon incorporation of the star's inclination and the planet's orbital inclination, we determined a true obliquity for TOI-942c of $ψ< 43$ degrees at 84\% confidence, while dynamic analysis strongly suggests TOI-942c is aligned with stellar spin and coplanar with the inner planet. Furthermore, TOI-942c is also a suitable target for studying atmospheric loss of young Neptunian planets that are likely still contracting from the heat of formation. We observed a blueshifted excess absorption in the H-alpha line at 6564.7 Å, potentially indicating atmospheric loss due to photoevaporation. However, due to the lack of pre-ingress data, additional observations are needed to confirm this measurement. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2408_07788 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The $\sim$50-Myr-Old TOI-942c is Likely on an Aligned, Coplanar Orbit and Losing Mass Teng, Huan-Yu Dai, Fei Howard, Andrew W. Isaacson, Howard Rubenzahl, Ryan A. Angelo, Isabel Polanski, Alex S. Earth and Planetary Astrophysics We report the observation of the transiting planet TOI-942c, a Neptunian planet orbiting a young K-type star approximately 50 Myr years old. Using Keck/HIRES, we observed a partial transit of the planet and detected an associated radial velocity anomaly. By modeling the Rossiter-McLaughlin (RM) effect, we derived a sky-projected obliquity of $\left|λ\right|=24^{+14}_{-14}$ degrees, indicating TOI-942c is in a prograde and likely aligned orbit. Upon incorporation of the star's inclination and the planet's orbital inclination, we determined a true obliquity for TOI-942c of $ψ< 43$ degrees at 84\% confidence, while dynamic analysis strongly suggests TOI-942c is aligned with stellar spin and coplanar with the inner planet. Furthermore, TOI-942c is also a suitable target for studying atmospheric loss of young Neptunian planets that are likely still contracting from the heat of formation. We observed a blueshifted excess absorption in the H-alpha line at 6564.7 Å, potentially indicating atmospheric loss due to photoevaporation. However, due to the lack of pre-ingress data, additional observations are needed to confirm this measurement. |
| title | The $\sim$50-Myr-Old TOI-942c is Likely on an Aligned, Coplanar Orbit and Losing Mass |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2408.07788 |