J/A+A/693/A90ivo://CDS.VizieR/J/A+A/693/A90doi:10.26093/cds/vizier.36930090CDSBonfanti A.Amateis I.Gandolfi D.Borsato L.Egger J.A.Cubillos P.E.,Armstrong D.Leao I.C.Fridlund M.Canto Martins B.L.Sousa S.G.,De Medeiros J.R.Fossati L.Adibekyan V.Collier Cameron A.Grziwa S.,Lam K.W.F.Goffo E.Nielsen L.D.Rodler F.Alarcon J.Lillo-Box J.,Cochran W.D.Luque R.Redfield S.Santos N.C.Barros S.C.C.Bayliss D.,Dumusque X.Keniger M.A.F.Livingston J.Murgas F.Nowak G.Osborn A.,Osborn H.P.Palle E.Persson C.M.Serrano L.M.Strom P.A.Udry S.,Wheatley P.J.2025-03-03T20:01:53Z2025-01-07T09:13:18ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsphotometryradial-velocityvisible-astronomyTOI-396 is an F6 V, bright, naked-eye star (V~6.4) orbited by three transiting small (R_p_~2R_{sun}_) planets discovered thanks to space-based photometry from 2 TESS sectors. The orbital periods of the two innermost planets, namely TOI-396 b and c, are close to the 5:3 commensurability (P_b_~3.6d and P_c_~6.0d), suggesting that the planets might be trapped in a mean motion resonance (MMR) To measure the masses of the three planets, refine their radii, and investigate whether planets b and c are in MMR, we carried out HARPS radial velocity (RV) observations of TOI-396 and retrieved archival high-precision transit photometry from 4 TESS sectors. We extracted the RVs via a skew-normal fit onto the \harps cross correlation functions and performed a Markov chain Monte Carlo joint analysis of the Doppler measurements and transit photometry, while employing the breakpoint method to remove stellar activity from the RV time series. We also performed a transit timing variation (TTV) dynamical analysis of the system and simulated the temporal evolution of the TTV amplitudes of the three planets following an N-body numerical integration. Our analysis confirms that the three planets have similar sizes (R_b_=2.004_-0.047_^+0.045^R_{sun}_; R_c_=1.979_-0.051_^+0.054^R_{sun}_; R_d_=2.001_-0.064_^+0.063^R_{sun}_), in agreement with previous findings. Notably, our measurements are ~1.4 times more precise, thanks to the use of two additional TESS sectors. For the first time, we determine RV masses for TOI-396 b and d, and find them to be M_b_=3.55_-0.96_^+0.94^M_{sun}_ and M_d_=7.1+/-1.6M_{sun}_, implying bulk densities of rho_b_=2.44_-0.68_^+0.69^g/cm^3^ and rho_d_=4.9_-1.1_^+1.2^g/cm^3^, respectively. Our results suggest a quite unusual system architecture, with the outermost planet being the densest. Based on a frequency analysis of the HARPS activity indicators and TESS light curves, we find the rotation period of the star to be Prot=6.7+/-1.3d, in agreement with the value predicted from logR'_HK_-based empirical relations. The Doppler reflex motion induced by TOI-396 c remains undetected in our RV time series, likely due to the proximity of the planet's orbital period to the star's rotation period. We also discovered that TOI-396 b and c display significant TTVs. While the TTV dynamical analysis returns a formally precise mass for TOI-396 c of M_c,dyn_=2.24^+0.13^_-0.67_M_{sun}_, the result might not be accurate, owing to the poor sampling of the TTV phase. We also conclude that TOI-396 b and c are close to-, but out of- the 5:3 MMR. A TTV dynamical analysis of additional transit photometry evenly covering the TTV phase and super-period is likely the most effective approach for precisely and accurately determining the mass of TOI-396 c. Our numerical simulation suggests TTV semi-amplitudes of up to 5 hours over a temporal baseline of ~5.2 years, which should be duly taken into account when scheduling future observations of TOI-396.2025A&A...693A..90Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/693/A90CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/693/A90https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/693/A90http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/693/A90https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/693/A90https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/693/A90http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/693/A90GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/693/A90/tablea1RV time series extracted from HARPSrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDObservation time (TDB) (BJD-2450000)time.epochdoubleRVRadial velocity as extracted from the SN fit onto the CCFsm/sphys.veloc;pos.heliocentricfloate_RVError on the radial velocitym/sstat.errorfloatFWHMSNFWHM of the fitted skew-Normal functionkm/sspect.line.widthfloatAContrast of the fitted skew-Normal function%phot.flux;arith.ratiofloatgammaSkewness of the fitted skew-Normal functionstat.fit.paramfloatRVdDetrended Radial velocitym/sphys.veloc;pos.heliocentricfloate_RVdErrors on the detrended radial velocity (jitter included)m/sstat.errorfloatJ/A+A/693/A90/tablea2Polynomial detrending applied to TESS LCsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLC-IDTESS LC identifiermeta.id;meta.filecharPlanetPlanet(s) transiting in that LCmeta.id;meta.maincharDetrendPolynomials applied for detrending the LCsstat.fit.paramcharJ/A+A/693/A90/tablea3Transit timings and TTVsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDTransit timingdtime.epochdoublee_JDLower error on transit timingdstat.error;time.epochfloatE_JDUpper error on transit timingdstat.error;stat.maxfloatTTVTTV amplitude wrt linear ephemeridesminsrc.var.amplitudefloate_TTVLower error on the TTV amplitudeminstat.errorfloatE_TTVUpper error on the TTV amplitudeminstat.error;stat.maxfloatSectorTESS sector containing the transit eventmeta.noteintJ/A+A/693/A90/tablea4Interior structure parameters of TOI-396 brecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFractionsMass- (w), molar- (x), or water (Z) fractionsstat.fit.paramcharWR-A1Water-rich scenario Stellar priors on Si-Mg-Fe%stat.fit.paramfloate_WR-A1Lower errors on WR_A1 fractions%stat.errorfloatE_WR-A1Upper errors on WR_A1 fractions%stat.error;stat.maxfloatWR-A2Water-rich scenario Fe-enriched priors%stat.fit.paramfloate_WR-A2Lower errors on WR_A2 fractions%stat.errorfloatE_WR-A2Upper errors on WR_A2 fractions%stat.error;stat.maxfloatWR-A3Water-rich scenario Free priors on Si-Mg-Fe%stat.fit.paramfloate_WR-A3Lower errors on WR_A3 fractions%stat.errorfloatE_WR-A3Upper errors on WR_A3 fractions%stat.error;stat.maxfloatWP-B1Water-poor scenario Stellar priors on Si-Mg-Fe%stat.fit.paramfloate_WP-B1Lower errors on WP_B1 fractions%stat.errorfloatE_WP-B1Upper errors on WP_B1 fractions%stat.error;stat.maxfloatWP-B2Water-poor scenario Fe-enriched priors%stat.fit.paramfloate_WP-B2Lower errors on WP_B2 fractions%stat.errorfloatE_WP-B2Upper errors on WP_B2 fractions%stat.error;stat.maxfloatWP-B3Water-poor scenario Free priors on Si-Mg-Fe%stat.fit.paramfloate_WP-B3Lower errors on WP_B3 fractions%stat.errorfloatE_WP-B3Upper errors on WP_B3 fractions%stat.error;stat.maxfloatJ/A+A/693/A90/tablea5Interior structure parameters of TOI-396 de_WR-A3Lower errors on WR_A3 fractions%stat.errorfloatE_WR-A3Upper errors on WR_A3 fractions%stat.error;stat.maxfloate_WR-A1Lower errors on WR_A1 fractions%stat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFractionsMass- (w), molar- (x), or water (Z) fractionsstat.fit.paramcharWR-A1Water-rich scenario Stellar priors on Si-Mg-Fe%stat.fit.paramfloatE_WR-A1Upper errors on WR_A1 fractions%stat.error;stat.maxfloatWR-A2Water-rich scenario Fe-enriched priors%stat.fit.paramfloate_WR-A2Lower errors on WR_A2 fractions%stat.errorfloatE_WR-A2Upper errors on WR_A2 fractions%stat.error;stat.maxfloatWR-A3Water-rich scenario Free priors on Si-Mg-Fe%stat.fit.paramfloatWP-B1Water-poor scenario Stellar priors on Si-Mg-Fe%stat.fit.paramfloate_WP-B1Lower errors on WP_B1 fractions%stat.errorfloatE_WP-B1Upper errors on WP_B1 fractions%stat.error;stat.maxfloatWP-B2Water-poor scenario Fe-enriched priors%stat.fit.paramfloate_WP-B2Lower errors on WP_B2 fractions%stat.errorfloatE_WP-B2Upper errors on WP_B2 fractions%stat.error;stat.maxfloatWP-B3Water-poor scenario Free priors on Si-Mg-Fe%stat.fit.paramfloate_WP-B3Lower errors on WP_B3 fractions%stat.errorfloatE_WP-B3Upper errors on WP_B3 fractions%stat.error;stat.maxfloat