The misaligned orbit of the Earth-sized planet Kepler-408b. (arXiv:1902.02057v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kamiaka_S/0/1/0/all/0/1">Shoya Kamiaka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Benomar_O/0/1/0/all/0/1">Othman Benomar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suto_Y/0/1/0/all/0/1">Yasushi Suto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dai_F/0/1/0/all/0/1">Fei Dai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Masuda_K/0/1/0/all/0/1">Kento Masuda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Winn_J/0/1/0/all/0/1">Joshua N. Winn</a>
Kepler-408 is one of the 33 planet-hosting {it Kepler} stars for which
asteroseismology has been used to investigate the orientation of the stellar
rotation axis relative to the planetary orbital plane. The transiting “hot
Earth,” Kepler-408b, has an orbital period of 2.5 days and a radius of
$0.86$~$R_oplus$, making it much smaller than the planets for which spin-orbit
alignment has been studied using the Rossiter-McLaughlin effect. Because
conflicting asteroseismic results have been reported in the literature, we
undertake a thorough re-appraisal of this system and perform numerous checks
for consistency and robustness. We find that the conflicting results are due to
the different models for the low-frequency noise in the power spectrum. A
careful treatment of the background noise resolves these conflicts, and shows
that the stellar inclination is $is=42^{+5}_{-4}$ degrees. Kepler-408b is, by
far, the smallest planet known to have a significantly misaligned orbit.
Kepler-408 is one of the 33 planet-hosting {it Kepler} stars for which
asteroseismology has been used to investigate the orientation of the stellar
rotation axis relative to the planetary orbital plane. The transiting “hot
Earth,” Kepler-408b, has an orbital period of 2.5 days and a radius of
$0.86$~$R_oplus$, making it much smaller than the planets for which spin-orbit
alignment has been studied using the Rossiter-McLaughlin effect. Because
conflicting asteroseismic results have been reported in the literature, we
undertake a thorough re-appraisal of this system and perform numerous checks
for consistency and robustness. We find that the conflicting results are due to
the different models for the low-frequency noise in the power spectrum. A
careful treatment of the background noise resolves these conflicts, and shows
that the stellar inclination is $is=42^{+5}_{-4}$ degrees. Kepler-408b is, by
far, the smallest planet known to have a significantly misaligned orbit.
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