TOI-880 is an Aligned, Coplanar, Multi-planet System

Fuente: arXiv
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Main Authors: Zhang, Elina Y., Teng, Huan-Yu, Dai, Fei, Howard, Andrew W., Halverson, Samuel P., Isaacson, Howard, Rubenzahl, Ryan A., Wang, Xian-Yu, Wang, Songhu, Fulton, Benjamin J., Nielsen, Louise D., Lubin, Jack, Giacalone, Steven, Handley, Luke B., Petigura, Erik A., Turtelboom, Emma V., Polanski, Alex S., Gibson, Steve R., Rider, Kodi, Roy, Arpita, Baker, Ashley, Edelstein, Jerry, Smith, Christopher L., Walawender, Josh, Winn, Joshua N.
Format: Preprint
Published: 2025
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author Zhang, Elina Y.
Teng, Huan-Yu
Dai, Fei
Howard, Andrew W.
Halverson, Samuel P.
Isaacson, Howard
Rubenzahl, Ryan A.
Wang, Xian-Yu
Wang, Songhu
Fulton, Benjamin J.
Nielsen, Louise D.
Lubin, Jack
Giacalone, Steven
Handley, Luke B.
Petigura, Erik A.
Turtelboom, Emma V.
Polanski, Alex S.
Gibson, Steve R.
Rider, Kodi
Roy, Arpita
Baker, Ashley
Edelstein, Jerry
Smith, Christopher L.
Walawender, Josh
Winn, Joshua N.
author_facet Zhang, Elina Y.
Teng, Huan-Yu
Dai, Fei
Howard, Andrew W.
Halverson, Samuel P.
Isaacson, Howard
Rubenzahl, Ryan A.
Wang, Xian-Yu
Wang, Songhu
Fulton, Benjamin J.
Nielsen, Louise D.
Lubin, Jack
Giacalone, Steven
Handley, Luke B.
Petigura, Erik A.
Turtelboom, Emma V.
Polanski, Alex S.
Gibson, Steve R.
Rider, Kodi
Roy, Arpita
Baker, Ashley
Edelstein, Jerry
Smith, Christopher L.
Walawender, Josh
Winn, Joshua N.
contents Although many cases of stellar spin-orbit misalignment are known, it is usually unclear whether a single planet's orbit was tilted or if the entire protoplanetary disk was misaligned. Measuring stellar obliquities in multi-transiting planetary systems helps to distinguish these possibilities. Here, we present a measurement of the sky-projected spin-orbit angle for TOI-880 c (TOI-880.01), a member of a system of three transiting planets, using the Keck Planet Finder (KPF). We found that the host star is a K-type star ($T_{\rm eff}=5050 \pm 100$ K). Planet b (TOI-880.02) has a radius of $2.19\pm0.11\mathrm{R_{\oplus}}$ and an orbital period of $2.6$ days; planet c (TOI-880.01) is a Neptune-sized planet with $4.95\pm0.20\mathrm{R_{\oplus}}$ on a $6.4$-day orbit; and planet d (TOI-880.03) has a radius of $3.40_{-0.21}^{+0.22}\mathrm{R_{\oplus}}$ and a period of $14.3$ days. By modeling the Rossiter-McLaughlin (RM) effect, we found the sky-projected obliquity to be $|λ_c| = 7.4_{-7.2}^{+6.8}$$^{\circ}$, consistent with a prograde, well-aligned orbit. The lack of detectable rotational modulation of the flux of the host star and a low $\rm v\sin{i_\star}$ (1.6~km/s) imply slow rotation and correspondingly slow nodal precession of the planetary orbits and the expectation that the system will remain in this coplanar configuration. TOI-880 joins a growing sample of well-aligned, coplanar, multi-transiting systems. Additionally, TOI-880 c is a promising target for JWST follow-up, with a transmission spectroscopy metric (TSM) of $\sim 170$. We could not detect clear signs of atmospheric erosion in the H$α$ line from TOI-880 c, as photoevaporation might have diminished for this mature planet.
format Preprint
id arxiv_https___arxiv_org_abs_2507_16194
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle TOI-880 is an Aligned, Coplanar, Multi-planet System
Zhang, Elina Y.
Teng, Huan-Yu
Dai, Fei
Howard, Andrew W.
Halverson, Samuel P.
Isaacson, Howard
Rubenzahl, Ryan A.
Wang, Xian-Yu
Wang, Songhu
Fulton, Benjamin J.
Nielsen, Louise D.
Lubin, Jack
Giacalone, Steven
Handley, Luke B.
Petigura, Erik A.
Turtelboom, Emma V.
Polanski, Alex S.
Gibson, Steve R.
Rider, Kodi
Roy, Arpita
Baker, Ashley
Edelstein, Jerry
Smith, Christopher L.
Walawender, Josh
Winn, Joshua N.
Earth and Planetary Astrophysics
Although many cases of stellar spin-orbit misalignment are known, it is usually unclear whether a single planet's orbit was tilted or if the entire protoplanetary disk was misaligned. Measuring stellar obliquities in multi-transiting planetary systems helps to distinguish these possibilities. Here, we present a measurement of the sky-projected spin-orbit angle for TOI-880 c (TOI-880.01), a member of a system of three transiting planets, using the Keck Planet Finder (KPF). We found that the host star is a K-type star ($T_{\rm eff}=5050 \pm 100$ K). Planet b (TOI-880.02) has a radius of $2.19\pm0.11\mathrm{R_{\oplus}}$ and an orbital period of $2.6$ days; planet c (TOI-880.01) is a Neptune-sized planet with $4.95\pm0.20\mathrm{R_{\oplus}}$ on a $6.4$-day orbit; and planet d (TOI-880.03) has a radius of $3.40_{-0.21}^{+0.22}\mathrm{R_{\oplus}}$ and a period of $14.3$ days. By modeling the Rossiter-McLaughlin (RM) effect, we found the sky-projected obliquity to be $|λ_c| = 7.4_{-7.2}^{+6.8}$$^{\circ}$, consistent with a prograde, well-aligned orbit. The lack of detectable rotational modulation of the flux of the host star and a low $\rm v\sin{i_\star}$ (1.6~km/s) imply slow rotation and correspondingly slow nodal precession of the planetary orbits and the expectation that the system will remain in this coplanar configuration. TOI-880 joins a growing sample of well-aligned, coplanar, multi-transiting systems. Additionally, TOI-880 c is a promising target for JWST follow-up, with a transmission spectroscopy metric (TSM) of $\sim 170$. We could not detect clear signs of atmospheric erosion in the H$α$ line from TOI-880 c, as photoevaporation might have diminished for this mature planet.
title TOI-880 is an Aligned, Coplanar, Multi-planet System
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2507.16194