Orbit of a Possible Planet X
The plausibility of an unseen planet in the outer solar system, and the expected orbit and mass of such a planet, have long been a topic of inquiry and debate. We calculate the long-term orbital stability of distant trans-Neptunian objects (TNOs), which allows us to expand the sample of objects that...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad98f6 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1841556233377546240 |
|---|---|
| author | Amir Siraj Christopher F. Chyba Scott Tremaine |
| author_facet | Amir Siraj Christopher F. Chyba Scott Tremaine |
| author_sort | Amir Siraj |
| collection | DOAJ |
| description | The plausibility of an unseen planet in the outer solar system, and the expected orbit and mass of such a planet, have long been a topic of inquiry and debate. We calculate the long-term orbital stability of distant trans-Neptunian objects (TNOs), which allows us to expand the sample of objects that would carry dynamical information about a hypothetical unseen planet in the solar system. Using this expanded sample, we find statistically significant clustering at the ∼3 σ level for TNOs with semimajor axes > 170 au in the longitude of perihelion ( ϖ ), but not in inclination ( i ), argument of perihelion ( ω ), or longitude of node (Ω). Since a natural explanation for clustering in ϖ is an unseen planet, we run 300 N -body simulations with the giant planets, a disk of test particles representing Kuiper Belt objects, and an additional planet with varied initial conditions for its mass, semimajor axis, eccentricity, and inclination. Based on the distribution of test particles after 1–2 Gyr, we compute relative likelihoods given the actual distribution of ϖ as a function of semimajor axis for distant TNOs on stable orbits using a significantly larger sample than previous work. We find the best-fit unseen planet parameters to have mass m _p = 4.4 ± 1.1 M _⊕ , semimajor axis a _p = 290 ± 30 au, eccentricity e _p = 0.29 ± 0.13, and inclination i _p = 6 $\mathop{.}\limits^{\unicode{x000b0}}$ 8 ± 5 $\mathop{.}\limits^{\unicode{x000b0}}$ 0. Only 0.06% of the M. E. Brown & K. Batygin Planet Nine reference population produce probabilities within 1 σ of the maximum within our quadrivariate model, indicating that our work identifies a distinct preferred region of parameter space for an unseen planet in the solar system. |
| format | Article |
| id | doaj-art-7f1d68bd398248f6aca466d31f4f1466 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-7f1d68bd398248f6aca466d31f4f14662025-01-07T12:58:39ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01978213910.3847/1538-4357/ad98f6Orbit of a Possible Planet XAmir Siraj0https://orcid.org/0000-0002-9321-6016Christopher F. Chyba1https://orcid.org/0000-0002-6757-4522Scott Tremaine2https://orcid.org/0000-0002-0278-7180Department of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; siraj@princeton.eduDepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; siraj@princeton.edu; School of Public and International Affairs, Princeton University , 20 Prospect Lane, Princeton, NJ 08540, USASchool of Natural Sciences, Institute for Advanced Study , Princeton, NJ 08540, USAThe plausibility of an unseen planet in the outer solar system, and the expected orbit and mass of such a planet, have long been a topic of inquiry and debate. We calculate the long-term orbital stability of distant trans-Neptunian objects (TNOs), which allows us to expand the sample of objects that would carry dynamical information about a hypothetical unseen planet in the solar system. Using this expanded sample, we find statistically significant clustering at the ∼3 σ level for TNOs with semimajor axes > 170 au in the longitude of perihelion ( ϖ ), but not in inclination ( i ), argument of perihelion ( ω ), or longitude of node (Ω). Since a natural explanation for clustering in ϖ is an unseen planet, we run 300 N -body simulations with the giant planets, a disk of test particles representing Kuiper Belt objects, and an additional planet with varied initial conditions for its mass, semimajor axis, eccentricity, and inclination. Based on the distribution of test particles after 1–2 Gyr, we compute relative likelihoods given the actual distribution of ϖ as a function of semimajor axis for distant TNOs on stable orbits using a significantly larger sample than previous work. We find the best-fit unseen planet parameters to have mass m _p = 4.4 ± 1.1 M _⊕ , semimajor axis a _p = 290 ± 30 au, eccentricity e _p = 0.29 ± 0.13, and inclination i _p = 6 $\mathop{.}\limits^{\unicode{x000b0}}$ 8 ± 5 $\mathop{.}\limits^{\unicode{x000b0}}$ 0. Only 0.06% of the M. E. Brown & K. Batygin Planet Nine reference population produce probabilities within 1 σ of the maximum within our quadrivariate model, indicating that our work identifies a distinct preferred region of parameter space for an unseen planet in the solar system.https://doi.org/10.3847/1538-4357/ad98f6Solar systemTrans-Neptunian objects |
| spellingShingle | Amir Siraj Christopher F. Chyba Scott Tremaine Orbit of a Possible Planet X The Astrophysical Journal Solar system Trans-Neptunian objects |
| title | Orbit of a Possible Planet X |
| title_full | Orbit of a Possible Planet X |
| title_fullStr | Orbit of a Possible Planet X |
| title_full_unstemmed | Orbit of a Possible Planet X |
| title_short | Orbit of a Possible Planet X |
| title_sort | orbit of a possible planet x |
| topic | Solar system Trans-Neptunian objects |
| url | https://doi.org/10.3847/1538-4357/ad98f6 |
| work_keys_str_mv | AT amirsiraj orbitofapossibleplanetx AT christopherfchyba orbitofapossibleplanetx AT scotttremaine orbitofapossibleplanetx |