Research Outputs

Now showing 1 - 5 of 5
  • Publication
    Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS): IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b
    (Astronomy & Astrophysics, 2020)
    Hoeijmakers, H. J.
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    Seidel, J. V.
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    Pino, L.
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    Kitzmann, D.
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    Sindel, J. P.
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    Ehrenreich, D.
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    Oza, A. V.
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    Bourrier, V.
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    Allart, R.
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    Gebek, A.
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    Lovis, C.
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    Yurchenko, S. N.
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    Bayliss, D.
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    Cegla, H.
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    Lavie, B.
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    Lendl, M.
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    Melo, C.
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    Murgas, F.
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    Nascimbeni, V.
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    Pepe, F.
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    Ségransan, D.
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    Udry, S.
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    Wyttenbach, A.
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    Heng, K.
    WASP-121 b is a hot Jupiter that was recently found to possess rich emission (day side) and transmission (limb) spectra, suggestive of the presence of a multitude of chemical species in the atmosphere. Aims. We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution and elaborate on existing interpretations of the optical transmission spectrum observed with the Hubble Space Telescope (HST). Methods. We applied the cross-correlation technique and direct differential spectroscopy to search for sodium and other neutral and ionised atoms, TiO, VO, and SH in high-resolution transit spectra obtained with the HARPS spectrograph. We injected models assuming chemical and hydrostatic equilibrium with a varying temperature and composition to enable model comparison, and employed two bootstrap methods to test the robustness of our detections. Results. We detect neutral Mg, Na, Ca, Cr, Fe, Ni, and V, which we predict exists in equilibrium with a significant quantity of VO, supporting earlier observations by HST/WFC3. Non-detections of Ti and TiO support the hypothesis that Ti is depleted via a cold-trap mechanism, as has been proposed in the literature. Atomic line depths are under-predicted by hydrostatic models by a factor of 1.5 to 8, confirming recent findings that the atmosphere is extended. We predict the existence of significant concentrations of gas-phase TiO2, VO2, and TiS, which could be important absorbers at optical and near-IR wavelengths in hot Jupiter atmospheres. However, accurate line-list data are not currently available for them. We find no evidence for absorption by SH and find that inflated atomic lines can plausibly explain the slope of the transmission spectrum observed in the near-ultraviolet with HST. The Na I D lines are significantly broadened (FWHM ~50 to 70 km s−1) and show a difference in their respective depths of ~15 scale heights, which is not expected from isothermal hydrostatic theory. If this asymmetry is of astrophysical origin, it may indicate that Na I forms an optically thin envelope, reminiscent of the Na I cloud surrounding Jupiter, or that it is hydrodynamically outflowing.
  • Publication
    Discovery of a hot, transiting, Earth-sized planet and a second temperate, non-transiting planet around the M4 dwarf GJ 3473 (TOI-488)
    (Astronomy & Astrophysics, 2020)
    Kemmer, J.
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    Stock, S.
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    Kossakowski, D.
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    Kaminski, A.
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    Molaverdikhani, K.
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    Schlecker, M.
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    Caballero, J. A.
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    Amado, P. J.
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    Bonfils, X.
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    Ciardi, David
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    Collins, Karen A.
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    Espinoza, N.
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    Fukui, A.
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    Hirano, T.
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    Jenkins, J. M.
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    Latham, D. W.
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    Matthews, E. C.
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    Narita, N.
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    Pallé, E.
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    Parviainen, H.
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    Quirrenbach, A.
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    Reiners, A.
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    Ribas, I.
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    Ricker, G.
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    Schlieder, J. E.
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    Seager, S.
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    Vanderspek, R.
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    Winn, J. N.
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    Almenara, José Manuel
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    Bejar, V. J. S.
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    Bluhm, P.
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    Bouchy, F.
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    Boyd, P.
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    Christiansen, J. L.
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    Cifuentes, C.
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    Cloutier, Ryan
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    Collins, Kevin I.
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    Cortés Contreras, M.
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    Crossfield, Ian J. M.
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    Crouzet, N.
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    de Leon, J. P.
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    Della Rose, D. D.
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    Delfosse, X.
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    Dreizler, S.
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    Esparza Borges, E.
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    Essack, Z.
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    Forveille, Th.
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    Figueira, P.
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    Galadí Enríquez, D.
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    Gan, T.
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    Glidden, A.
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    Gonzales, E. J.
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    Guerra, P.
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    Harakawa, H.
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    Hatzes, A. P.
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    Henning, Th.
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    Herrero, E.
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    Hodapp, K.
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    Hori, Y.
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    Howell, S. B.
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    Ikoma, M.
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    Isogai, K.
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    Jeffers, S. V.
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    Kürster, M.
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    Kawauchi, K.
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    Kimura, T.
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    Klagyivik, P.
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    Kotani, T.
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    Kurokawa, T.
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    Kusakabe, N.
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    Kuzuhara, M.
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    Lafarga, M.
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    Livingston, J. H.
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    Luque, R.
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    Matson, R.
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    Morales, J. C.
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    Mori, M.
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    Muirhead, P. S.
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    Murgas, F.
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    Nishikawa, J.
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    Nishiumi, T.
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    Omiya, M.
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    Reffert, S.
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    Rodríguez López, C.
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    Santos, N. C.
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    Schöfer, P.
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    Schwarz, R. P.
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    Shiao, B.
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    Tamura, M.
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    Terada, Y.
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    Twicken, J. D.
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    Ueda, A.
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    Vievard, S.
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    Watanabe, N.
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    Zechmeister, M.
    We present the confirmation and characterisation of GJ 3473 b (G 50–16, TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose transiting signal (P = 1.198 003 5 ± 0.000 001 8 d) was first detected by the Transiting Exoplanet Survey Satellite (TESS). Through a joint modelling of follow-up radial velocity observations with CARMENES, IRD, and HARPS together with extensive ground-based photometric follow-up observations with LCOGT, MuSCAT, and MuSCAT2, we determined a precise planetary mass, Mb = 1.86 ± 0.30 M⊕, and radius, Rb = 1.264 ± 0.050 R⊕. Additionally, we report the discovery of a second, temperate, non-transiting planet in the system, GJ 3473 c, which has a minimum mass, Mc sin i = 7.41 ± 0.91 M⊕, and orbital period, Pc = 15.509 ± 0.033 d. The inner planet of the system, GJ 3473 b, is one of the hottest transiting Earth-sized planets known thus far, accompanied by a dynamical mass measurement, which makes it a particularly attractive target for thermal emission spectroscopy.
  • Publication
    Optical phase curve of the ultra-hot Jupiter WASP-121b
    (EDP Sciences, 2020)
    Bourrier, V.
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    Kitzmann, D.
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    Kuntzer, T.
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    Nascimbeni, V.
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    Lendl, M.
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    Lavie, B.
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    Hoeijmakers, H. J.
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    Pino, L.
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    Ehrenreich, D.
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    Heng, K.
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    Allart, R.
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    Cegla, H. M.
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    Dumusque, X.
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    Melo, C.
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    Caldwell, Douglas A.
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    Cretignier, M.
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    Giles, H.
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    Henze, C. E.
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    Jenkins, J.
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    Lovis, C.
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    Murgas, F.
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    Pepe, F.
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    Ricker, G. R.
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    Rose, M. E.
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    Seager, S.
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    Segransan, D.
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    Suárez-Mascareño, A.
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    Udry, S.
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    Vanderspek, R.
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    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.
  • Publication
    Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) III. Atmospheric structure of the misaligned ultra-hot Jupiter WASP-121b
    (Astronomy & Astrophysics, 2020)
    Bourrier, V.
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    Ehrenreich, D.
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    Lendl, M.
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    Cretignier, M.
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    Allart, R.
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    Dumusque, X.
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    Cegla, H. M.
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    Suarez Mascareno, A.
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    Wyttenbach, A.
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    Hoeijmakers, H. J.
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    Melo, C.
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    Kuntzer, T.
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    Giles, H.
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    Heng, K.
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    Kitzmann, D.
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    Lavie, B.
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    Lovis, C.
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    Murgas, F.
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    Nascimbeni, V.
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    Pepe, F.
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    Pino, L.
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    Segransan, D.
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    Udry, S.
    Ultra-hot Jupiters offer interesting prospects for expanding our theories on dynamical evolution and the properties of extremely irradiated atmospheres. In this context, we present the analysis of new optical spectroscopy for the transiting ultra-hot Jupiter WASP-121b. We first refine the orbital properties of WASP-121b, which is on a nearly polar (obliquity psi(North) = 88.1 +/- 0.25 degrees or psi(South) = 91.11 +/- 0.20 degrees) orbit, and exclude a high differential rotation for its fast-rotating (P < 1.13 days), highly inclined (i(star)i star North = 8.1(-2.6)(+3.0)degrees-2.6+3.0 degrees or i(star)(South) i star South = 171.9(-3.4)(+2.5)degrees-3.4+2.5 degrees ) star. We then present a new method that exploits the reloaded Rossiter-McLaughlin technique to separate the contribution of the planetary atmosphere and of the spectrum of the stellar surface along the transit chord. Its application to HARPS transit spectroscopy of WASP-121b reveals the absorption signature from metals, likely atomic iron, in the planet atmospheric limb. The width of the signal (14.3 +/- 1.2 km s(-1)) can be explained by the rotation of the tidally locked planet. Its blueshift (-5.2 +/- 0.5 km s(-1)) could trace strong winds from the dayside to the nightside, or the anisotropic expansion of the planetary thermosphere.
  • Publication
    Characterization of the L 98-59 multi-planetary system with HARPS Mass characterization of a hot super-Earth, a sub-Neptune, and a mass upper limit on the third planet
    (Astronomy & Astrophysics, 2019)
    Cloutier, Ryan
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    Bonfils, X.
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    Jenkins, J.S.
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    Berdiñas, Z.
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    Ricker, G.
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    Vanderspek, R.
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    Latham, D. W.
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    Seager, S.
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    Winn, J.
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    Jenkins, J. M.
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    Almenara, José Manuel
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    Bouchy, F.
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    Delfosse, X.
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    Díaz, M. R.
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    Díaz, R. F.
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    Doyon, R.
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    Figueira, P.
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    Forveille, T.
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    Kurtovic, N. T.
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    Lovis, C.
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    Mayor, M.
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    Menou, K.
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    Morgan, E.
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    Morris, R.
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    Muirhead, P.
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    Murgas, F.
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    Pepe, F.
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    Santos, N. C.
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    Ségransan, D.
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    Smith, J. C.
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    Tenenbaum, P.
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    Torres, G.
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    Udry, S.
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    Vezie, M.
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    Villasenor, J.
    Aims. L 98-59 (TIC 307210830, TOI-175) is a nearby M3 dwarf around which TESS revealed three small transiting planets (0.80, 1.35, 1.57 Earth radii) in a compact configuration with orbital periods shorter than 7.5 days. Here we aim to measure the masses of the known transiting planets in this system using precise radial velocity (RV) measurements taken with the HARPS spectrograph. Methods. We considered both trained and untrained Gaussian process regression models of stellar activity, which are modeled simultaneously with the planetary signals. Our RV analysis was then supplemented with dynamical simulations to provide strong constraints on the planets’ orbital eccentricities by requiring long-term stability. Results. We measure the planet masses of the two outermost planets to be 2.42 ± 0.35 and 2.31 ± 0.46 Earth masses, which confirms the bulk terrestrial composition of the former and eludes to a significant radius fraction in an extended gaseous envelope for the latter. We are able to place an upper limit on the mass of the smallest, innermost planet of <1.01 Earth masses with 95% confidence. Our RV plus dynamical stability analysis places strong constraints on the orbital eccentricities and reveals that each planet’s orbit likely has e < 0.1. Conclusions. L 98-59 is likely a compact system of two rocky planets plus a third outer planet with a lower bulk density possibly indicative of the planet having retained a modest atmosphere. The system offers a unique laboratory for studies of planet formation, dynamical stability, and comparative atmospheric planetology as the two outer planets are attractive targets for atmospheric characterization through transmission spectroscopy. Continued RV monitoring will help refine the characterization of the innermost planet andpotentially reveal additional planets in the system at wider separations.