J/A+A/701/A173ivo://CDS.VizieR/J/A+A/701/A173doi:10.26093/cds/vizier/bc-nx/lbhdCDSGrouffal S.Santerne A.Bourrier V.Kunovac V.Dressing C.,Akinsanmi B.Armstrong C.Baliwal S.Balsalobre-Ruza O.Barros S.C.C.,Bayliss D.Crossfield I.J.M.Demangeon O.Dumusque X.Giacalone S.,Harada C.K.Isaacson H.Kellermann H.Lillo-Box J.Llama J.Mortier A.,Palle E.Rajpurohit A.S.Rice M.Santos N.C.Seidel J.V.Sharma R.,Sousa S.G.Thomas L.Turtelboom E.V.Udry S.Wheatley P.J.2026-08-03T06:57:05Z2025-09-15T09:51:08ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmultiple-starsexoplanetsradial-velocityvisible-astronomyThe obliquity between the stellar spin axis and the planetary orbit, detected via the Rossiter-McLaughlin (RM) effect, is a tracer of the formation history of planetary systems. While obliquity measurements have been extensively applied to hot Jupiters and short-period planets, they remain rare for cold and long-period planets due to observational challenges, particularly their long transit durations. We report the detection of the RM effect for the 19-hour-long transit of HIP 41378 f, a temperate giant planet on a 542-day orbit, observed through a worldwide spectroscopic campaign. We measure a slight projected obliquity of 21+/-8{deg} and a significant 3D spin-orbit angle of 52+/-6{deg}, based on the measurement of the stellar rotation period. HIP 41378 f is part of a 5-transiting planetary system with planets close to mean motion resonances. The observed misalignment likely reflects a primordial tilt of the stellar spin axis relative to the protoplanetary disk, rather than dynamical interactions. HIP 41378 f is the first non-eccentric long-period (P>100 days) planet observed with the RM effect, opening new constraints on planetary formation theories. This observation should motivate the exploration of planetary obliquities across a longer range of orbital distances through international collaboration.2025A&A...701A.173Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/701/A173CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/686/L18 : HIP 41378 velocity curve (Sulis+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/701/A173https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/701/A173http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/701/A173https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/701/A173https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/701/A173http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/701/A173GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/701/A173/rvCARMEMES, ESPRESSO, EXPRES, MERCATOR, NEID and PARAS radial velocities of HIP 41378recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintInstInstrumentmeta.id;instrcharBJDBaricentric Julian date (BJD)dtime.epochdoubleRVRadial Velocitym/sphys.veloc;pos.heliocentricdoublee_RVRadial Velocity errorm/sstat.errordoubleJ/A+A/701/A173/drvHARPSN, HIRES and MaHPS relative radial velocities of HIP 41378recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintInstInstrumentmeta.id;instrcharBJDBaricentric Julian date (BJD)dtime.epochdoubledRVRelative radial Velocitym/sphys.veloc;arith.diffdoublee_dRVRelative radial Velocity errorm/sstat.errordouble