2026AJ....171..139B -
Astron. J., 171, 139 (2026/March-0)
Aligned, Misaligned, and Polar Orbits of Hot Jupiters: Measuring Spin-orbit Angles via Doppler Tomography with HARPS-N.
BALKOOVA Z., ZAK J., SKARKA M., KNUDSTRUP E., GAJDOS P., BIGNAMINI A. and KABATH P.
Abstract (from CDS):
Although the migration of hot Jupiters is not yet fully understood, measurements of the projected spin-orbit angle λ help shed light on the processes involved. Here we present Doppler tomography of three known hot Jupiters to determine their λ orientation: HAT-P-49 b, HAT-P-57 A b, and XO-3 A b. Our analysis explores the impact of cross-correlation processing methods on the detectability and characterization of the planet's Doppler shadow using up to three independent routines for cross-correlation functions extraction; those being: Yabi, iSpec, and IRAF. After accounting for differences among the results obtained with the various routines, we report: first, the HAT-P-49 system is a case of a hot Jupiter on a polar orbit with λ = -85$\mathop{.}\limits^{\unicode{x000b0}}$3 ± 1$\mathop{.}\limits^{\unicode{x000b0}}$7, second, HAT-P-57 A indicates practically no deviation of the planet's projected orbit from the host's equatorial plane with $\lambda =\,\unicode{x02013}\,0.{4}_{-1.9}^{+1.4}{^\circ} $, and third, the XO-3 A system with the measured value of $\lambda =3{8}_{-4}^{+3}{^\circ} $ lies in between an aligned and a perpendicular orientation, which is a less populated region of the spin-orbit distribution. Our findings highlight both the diversity of spin-orbit angles among close-in giant planets and the potential discrepancies in their measurement that can arise from different approaches to constructing the cross-correlation functions.
Abstract Copyright:
© 2026. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Exoplanets - Planetary system evolution - Exoplanet migration - Hot Jupiters
Simbad objects:
12
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