A 34.6-day transiting sub-Neptune in the TOI-1422 planetary system
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| Autores principales: | , , , , , , , , , , , |
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| Formato: | Preprint |
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2025
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| author | Naponiello, L. Leonardi, P. Damasso, M. Steinmeyer, M. -L. Stalport, M. Dorn, C. Bonomo, A. S. Mancini, L. Sozzetti, A. Benatti, S. Colombo, S. Cosentino, R. |
| author_facet | Naponiello, L. Leonardi, P. Damasso, M. Steinmeyer, M. -L. Stalport, M. Dorn, C. Bonomo, A. S. Mancini, L. Sozzetti, A. Benatti, S. Colombo, S. Cosentino, R. |
| contents | TOI-1422 is a G2 V star ($V = 10.6$ mag) known to host a warm Neptune-sized planet, TOI-1422 b, with a mass and radius of about $9M_{\oplus}$ and $4R_{\oplus}$, on a circular orbit with a period of $12.997$ days. An outer planetary candidate in this system had previously been suggested on the basis of a residual signal in the radial velocity (RV) data with a tentative period of $\sim$29 days, along with a possible single transit-like event, although it was not clear at the time whether the two signals belonged to the same companion. In this work, we confirm the presence of a second transiting planet, TOI-1422 c, a sub-Neptune ($R=2.61\pm0.14 R_{\oplus}$) that orbits with a longer period of 34.563 days. This confirmation is based on the detection of three TESS transits, two from newly available sectors, combined with new and archival RV measurements. The sub-Neptune ($ρ_{\rm c}=4.3^{+1.3}_{-1.0}$ g cm$^{-3}$) is more massive than the inner Neptune ($ρ_{\rm b}=0.93^{+0.21}_{-0.20}$ g cm$^{-3}$), having a mass of $M_{\rm c}=14\pm3 M_{\oplus}$, making TOI-1422 a rare anti-ordered system. Furthermore, we detect transit timing variations (TTVs) on the inner planet, with amplitudes of up to 5 hours, suggesting ongoing dynamical interactions. A dynamical analysis that combined TTVs and RVs indicates that planet c alone is unlikely to account for the full TTV amplitude observed on TOI-1422 b. We investigated whether an additional, as yet undetected companion could account for the observed signal, exploring a range of plausible orbital configurations and finding that a low-mass planet located between the two known orbits may be responsible. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_11492 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A 34.6-day transiting sub-Neptune in the TOI-1422 planetary system Naponiello, L. Leonardi, P. Damasso, M. Steinmeyer, M. -L. Stalport, M. Dorn, C. Bonomo, A. S. Mancini, L. Sozzetti, A. Benatti, S. Colombo, S. Cosentino, R. Earth and Planetary Astrophysics TOI-1422 is a G2 V star ($V = 10.6$ mag) known to host a warm Neptune-sized planet, TOI-1422 b, with a mass and radius of about $9M_{\oplus}$ and $4R_{\oplus}$, on a circular orbit with a period of $12.997$ days. An outer planetary candidate in this system had previously been suggested on the basis of a residual signal in the radial velocity (RV) data with a tentative period of $\sim$29 days, along with a possible single transit-like event, although it was not clear at the time whether the two signals belonged to the same companion. In this work, we confirm the presence of a second transiting planet, TOI-1422 c, a sub-Neptune ($R=2.61\pm0.14 R_{\oplus}$) that orbits with a longer period of 34.563 days. This confirmation is based on the detection of three TESS transits, two from newly available sectors, combined with new and archival RV measurements. The sub-Neptune ($ρ_{\rm c}=4.3^{+1.3}_{-1.0}$ g cm$^{-3}$) is more massive than the inner Neptune ($ρ_{\rm b}=0.93^{+0.21}_{-0.20}$ g cm$^{-3}$), having a mass of $M_{\rm c}=14\pm3 M_{\oplus}$, making TOI-1422 a rare anti-ordered system. Furthermore, we detect transit timing variations (TTVs) on the inner planet, with amplitudes of up to 5 hours, suggesting ongoing dynamical interactions. A dynamical analysis that combined TTVs and RVs indicates that planet c alone is unlikely to account for the full TTV amplitude observed on TOI-1422 b. We investigated whether an additional, as yet undetected companion could account for the observed signal, exploring a range of plausible orbital configurations and finding that a low-mass planet located between the two known orbits may be responsible. |
| title | A 34.6-day transiting sub-Neptune in the TOI-1422 planetary system |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2511.11492 |