Research Outputs

Now showing 1 - 3 of 3
  • Publication
    Optical phase curve of the ultra-hot Jupiter WASP-121b
    (EDP Sciences, 2020)
    Bourrier, V.
    ;
    Kitzmann, D.
    ;
    Kuntzer, T.
    ;
    Nascimbeni, V.
    ;
    Lendl, M.
    ;
    Lavie, B.
    ;
    Hoeijmakers, H. J.
    ;
    Pino, L.
    ;
    Ehrenreich, D.
    ;
    Heng, K.
    ;
    Allart, R.
    ;
    Cegla, H. M.
    ;
    Dumusque, X.
    ;
    Melo, C.
    ;
    ;
    Caldwell, Douglas A.
    ;
    Cretignier, M.
    ;
    Giles, H.
    ;
    Henze, C. E.
    ;
    Jenkins, J.
    ;
    Lovis, C.
    ;
    Murgas, F.
    ;
    Pepe, F.
    ;
    Ricker, G. R.
    ;
    Rose, M. E.
    ;
    Seager, S.
    ;
    Segransan, D.
    ;
    Suárez-Mascareño, A.
    ;
    Udry, S.
    ;
    Vanderspek, R.
    ;
    Wyttenbach, A.
    We present the analysis of TESS optical photometry of WASP-121b, which reveals the phase curve of this transiting ultra-hot Jupiter. Its hotspot is located at the sub-stellar point, showing inefficient heat transport from the dayside (2870 ± 50 K) to the nightside (<2500 K at 3σ) at the altitudes probed by TESS. The TESS eclipse depth, measured at the shortest wavelength to date for WASP-121b, confirms the strong deviation from blackbody planetary emission. Our atmospheric retrieval on the complete emission spectrum supports the presence of a temperature inversion, which can be explained by the presence of VO and possibly TiO and FeH. The strong planetary emission at short wavelengths could arise from an H− continuum.
  • Thumbnail Image
    Publication
    Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS). VI. Non-detection of sodium with HARPS on the bloated super-Neptune WASP-127b
    (EDP Sciences, 2020) ;
    Seidel, J.
    ;
    Lendl, M.
    ;
    Bourrier, V.
    ;
    Ehrenreich, D.
    ;
    Allart, R.
    ;
    Sousa, S. G.
    ;
    Cegla, H. M.
    ;
    Bonfils, X.
    ;
    Conod, U.
    ;
    Grandjean, A.
    ;
    Wyttenbach, A.
    ;
    Bayliss, D.
    ;
    Heng, K.
    ;
    Lavie, B.
    ;
    Lovis, C.
    ;
    Melo, C.
    ;
    Pepe, F.
    ;
    Ségransan, D.
    ;
    Udry, S.
    WASP-127b is one of the puffiest exoplanets found to date, with a mass of only 3.4 Neptune masses, but a radius larger than that of Jupiter. It is located at the border of the Neptune desert, which describes the lack of highly irradiated Neptune-sized planets, and which remains poorly understood. Its large scale height and bright host star make the transiting WASP-127b a valuable target to characterise in transmission spectroscopy. We used combined EulerCam and TESS light curves to recalculate the system parameters. Additionally, we present an in-depth search for sodium in four transit observations of WASP-127b, obtained as part of the Hot Exoplanet Atmosphere Resolved with Transit Spectroscopy (HEARTS) survey with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. Two nights from this dataset were analysed independently by another team. The team claimed a detection of sodium that is incompatible with previous studies of data from both ground and space. We show that this strong sodium detection is due to contamination from telluric sodium emissions and the low signal-to-noise ratio in the core of the deep stellar sodium lines. When these effects are properly accounted for, the previous sodium signal is reduced to an absorption of 0.46 ± 0.20% (2.3σ), which is compatible with analyses of WASP-127b transits carried out with other instruments. We can fit a Gaussian to the D2 line, but the D1 line was not detected. This indicates an unusual line ratio if sodium exists in the atmosphere. Follow-up of WASP-127 at high resolution and with high sensitivity is required to firmly establish the presence of sodium and analyse its line shape.
  • Thumbnail Image
    Publication
    The SOPHIE search for northern extrasolar planets. XIX. A system including a cold sub-Neptune potentially transiting a V = 6.5 star HD 88986
    (EDP ​​​​Sciences, 2024) ;
    Heidari, N.
    ;
    Boisse, I.
    ;
    Hara, N.
    ;
    Wilson, T.
    ;
    Kiefer, F.
    ;
    Hébrard, G.
    ;
    Philipot, F.
    ;
    Hoyer, S.
    ;
    Stassun, K.
    ;
    Henry, G.
    ;
    Santos, N.
    ;
    Acuña, L.
    ;
    Almasian, D.
    ;
    Arnold, L.
    ;
    Attia, O.
    ;
    Bonfils, X.
    ;
    Bouchy, F.
    ;
    Bourrier, V.
    ;
    Collet, B.
    ;
    Cortés-Zuleta, P.
    ;
    Carmona, A.
    ;
    Delfosse, X.
    ;
    Dalal, S.
    ;
    Deleuil, M.
    ;
    Demangeon, O.
    ;
    Díaz, R.
    ;
    Dumusque, X.
    ;
    Ehrenreich, D.
    ;
    Forveille, T.
    ;
    Hobson, M.
    ;
    Jenkins, J.
    ;
    Jenkins, J.
    ;
    Lagrange, A.
    ;
    Latham, D.
    ;
    Larue, P.
    ;
    Liu, J.
    ;
    Moutou, C.
    ;
    Mignon, L.
    ;
    Osborn, H.
    ;
    Pepe, F.
    ;
    Rapetti, D.
    ;
    Rodrigues, J.
    ;
    Santerne, A.
    ;
    Segransan, D.
    ;
    Shporer, A.
    ;
    Sulis, S.
    ;
    Torres, G.
    ;
    Udry, S.
    ;
    Vakili, F.
    ;
    Vanderburg, A.
    ;
    Venot, O.
    ;
    Vivien, H.
    ;
    Vines, J.
    Transiting planets with orbital periods longer than 40 d are extremely rare among the 5000+ planets discovered so far. The lack of discoveries of this population poses a challenge to research into planetary demographics, formation, and evolution. Here, we present the detection and characterization of HD 88986 b, a potentially transiting sub-Neptune, possessing the longest orbital period among known transiting small planets (<4 R⊕) with a precise mass measurement (σM/M > 25%). Additionally, we identified the presence of a massive companion in a wider orbit around HD 88986. To validate this discovery, we used a combination of more than 25 yr of extensive radial velocity (RV) measurements (441 SOPHIE data points, 31 ELODIE data points, and 34 HIRES data points), Gaia DR3 data, 21 yr of photometric observations with the automatic photoelectric telescope (APT), two sectors of TESS data, and a 7-day observation of CHEOPS. Our analysis reveals that HD 88986 b, based on two potential single transits on sector 21 and sector 48 which are both consistent with the predicted transit time from the RV model, is potentially transiting. The joint analysis of RV and photometric data show that HD 88986 b has a radius of 2.49 ± 0.18 R⊕, a mass of 17.2−3.8+4.0 M⊕, and it orbits every 146.05−0.40+0.43 d around a subgiant HD 88986 which is one of the closest and brightest exoplanet host stars (G2Vtype, R = 1.543 ± 0.065 R⊙, V = 6.47 ± 0.01 mag, distance = 33.37 ± 0.04 pc). The nature of the outer, massive companion is still to be confirmed; a joint analysis of RVs, HIPPARCOS, and Gaia astrometric data shows that with a 3σ confidence interval, its semi-major axis is between 16.7 and 38.8 au and its mass is between 68 and 284 MJup. HD 88986 b’s wide orbit suggests the planet did not undergo significant mass loss due to extreme-ultraviolet radiation from its host star. Therefore, it probably maintained its primordial composition, allowing us to probe its formation scenario. Furthermore, the cold nature of HD 88986 b (460 ± 8 K), thanks to its long orbital period, will open up exciting opportunities for future studies of cold atmosphere composition characterization. Moreover, the existence of a massive companion alongside HD 88986 b makes this system an interesting case study for understanding planetary formation and evolution.