Early Evidence for Polar Orbits of Sub-Saturns Around Hot Stars
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866917037594378240 |
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| author | Dugan, Emma Wang, Xian-Yu Heron, Agustin Bhaskar, Hareesh Gautham Rice, Malena Petrovich, Cristobal Wang, Songhu |
| author_facet | Dugan, Emma Wang, Xian-Yu Heron, Agustin Bhaskar, Hareesh Gautham Rice, Malena Petrovich, Cristobal Wang, Songhu |
| contents | Sub-Saturns have been reported to preferentially occupy near-polar orbits, but this conclusion has so far been based primarily on systems with cool host stars; obliquity measurements for sub-Saturns orbiting hot stars remain scarce. Expanding the census into the hot-star regime is essential to test whether the polar preference persists across the Kraft break and to diagnose the underlying excitation mechanisms. In this work, we present Rossiter-McLaughlin observations of TOI-1135 b, a sub-Saturn orbiting a hot star with $T_{\rm eff}=6320\pm120$ K, using WIYN/NEID. We confirm its near-polar architecture, measuring a sky-projected obliquity of $λ=-68.1^{+7.5}_{-5.3}$ degrees and a true obliquity of $ψ=72.2^{+6.4}_{-6.6}$ degrees. Coupling our new measurement with stellar-obliquity data from the literature, we find that sub-Saturns and hot Jupiters around cool stars are unlikely to be drawn from the same parent distribution at the $5.2σ$ level, consistent with weaker tidal realignment induced by lower-mass planets. Of the two known misaligned sub-Saturns around hot stars, both are near-polar, suggesting that the polar preference may extend above the Kraft break. Moreover, their obliquities lie near $\sim 65$ degrees, supporting predictions from secular resonance crossing for sub-Saturns around rapidly rotating hot stars. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_20740 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Early Evidence for Polar Orbits of Sub-Saturns Around Hot Stars Dugan, Emma Wang, Xian-Yu Heron, Agustin Bhaskar, Hareesh Gautham Rice, Malena Petrovich, Cristobal Wang, Songhu Earth and Planetary Astrophysics Sub-Saturns have been reported to preferentially occupy near-polar orbits, but this conclusion has so far been based primarily on systems with cool host stars; obliquity measurements for sub-Saturns orbiting hot stars remain scarce. Expanding the census into the hot-star regime is essential to test whether the polar preference persists across the Kraft break and to diagnose the underlying excitation mechanisms. In this work, we present Rossiter-McLaughlin observations of TOI-1135 b, a sub-Saturn orbiting a hot star with $T_{\rm eff}=6320\pm120$ K, using WIYN/NEID. We confirm its near-polar architecture, measuring a sky-projected obliquity of $λ=-68.1^{+7.5}_{-5.3}$ degrees and a true obliquity of $ψ=72.2^{+6.4}_{-6.6}$ degrees. Coupling our new measurement with stellar-obliquity data from the literature, we find that sub-Saturns and hot Jupiters around cool stars are unlikely to be drawn from the same parent distribution at the $5.2σ$ level, consistent with weaker tidal realignment induced by lower-mass planets. Of the two known misaligned sub-Saturns around hot stars, both are near-polar, suggesting that the polar preference may extend above the Kraft break. Moreover, their obliquities lie near $\sim 65$ degrees, supporting predictions from secular resonance crossing for sub-Saturns around rapidly rotating hot stars. |
| title | Early Evidence for Polar Orbits of Sub-Saturns Around Hot Stars |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2510.20740 |