2024/08/01 by Thiago Ferreira, Malena Rice, Ferreira, Thiago +5 · 4 citations
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2408.00725
openalex publication_date 2024/08/01 · openalex created_date 2024/08/04 · openalex updated_date 2026/07/28
Brown dwarfs occupy a middle ground in mass space between gaseous giant planets and ultra-cool dwarf stars, and the characterisation of their orbital orientations may shed light on how these neighbouring objects form. We present an analysis of the Rossiter-McLaughlin (RM) effect across the transit of TOI-2533 b, a brown dwarf on a moderately eccentric (eb = 0.2476±0.0090) and wide-separation (ab/R_⋆ = 13.34±0.30) orbit around an F8-type star, using data from the NEID/WIYN spectrograph in combination with archival photometry and radial velocity observations. Spin-orbit analyses of brown dwarfs are relatively rare, and TOI-2533 stands out as the fifth brown dwarf system with a measured spin-orbit constraint. We derive a sky-projected stellar obliquity of λ= -7±14∘ for TOI-2533 b, finding that the brown dwarf is consistent with spin-orbit alignment. Our joint model also indicates that TOI-2533 b falls near the lower bound of the hydrogen-burning minimum mass range (Mb = 74.9±5.3 M\rm \tiny Jup). Ultimately, we find that TOI-2533 b is consistent with formation from disc fragmentation in a primordially spin-orbit aligned orientation, although we cannot rule out the possibility that the system has been tidally realigned during its lifetime.