Examinando por Autor "Crossfield, Ian J. M."
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Ítem A broadband thermal emission spectrum of the ultra-hot Jupiter WASP-18b(Nature Research, 2023-08) Coulombe, Louis-Philippe; Benneke, Björn; Challener, Ryan; Piette, Anjali A. A.; Wiser, Lindsey S.; Mansfield, Megan; MacDonald, Ryan J.; Beltz, Hayley; Feinstein, Adina D.; Radica, Michael; Savel, Arjun B.; Dos Santos, Leonardo A.; Bean, Jacob L.; Parmentier, Vivien; Wong, Ian; Rauscher, Emily; Komacek, Thaddeus D.; Kempton, Eliza M.-R.; Tan, Xianyu; Hammond, Mark; Lewis, Neil T.; Line, Michael R.; Lee, Elspeth K. H.; Shivkumar, Hinna; Crossfield, Ian J. M.; Nixon, Matthew C.; Rackham, Benjamin V.; Wakeford, Hannah R.; Welbanks, Luis; Zhang, Xi; Batalha, Natalie M.; Berta-Thompson, Zachory K.; Changeat, Quentin; Désert, Jean-Michel; Espinoza, Néstor; Goyal, Jayesh M.; Harrington, Joseph; Knutson, Heather A.; Kreidberg, Laura; López-Morales, Mercedes; Shporer, Avi; Sing, David K.; Stevenson, Kevin B.; Aggarwal, Keshav; Ahrer, Eva-Maria; Alam, Munazza K.; Bell, Taylor J.; Blecic, Jasmina; Caceres, Claudio; Carter, Aarynn L.; Casewell, Sarah L.; Crouzet, Nicolas; Cubillos, Patricio E.; Decin, Leen; Fortney, Jonathan J.; Gibson, Neale P.; Heng, Kevin; Henning, Thomas; Iro, Nicolas; Kendrew, Sarah; Lagage, Pierre-Olivier; Leconte, Jérémy; Lendl, Monika; Lothringer, Joshua D.; Mancini, Luigi; Mikal-Evans, Thomas; Molaverdikhani, Karan; Nikolov, Nikolay K.; Ohno, Kazumasa; Palle, Enric; Piaulet, Caroline; Redfield, Seth; Roy, Pierre-Alexis; Tsai, Shang-Min; Venot, Olivia; Wheatley, Peter J.Close-in giant exoplanets with temperatures greater than 2,000 K (‘ultra-hot Jupiters’) have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from the Hubble Space Telescope (HST) and Spitzer Space Telescope 1–3. However, previous studies have yielded inconsistent results because the small sizes of the spectral features and the limited information content of the data resulted in high sensitivity to the varying assumptions made in the treatment of instrument systematics and the atmospheric retrieval analysis 3–12. Here we present a dayside thermal emission spectrum of the ultra-hot Jupiter WASP-18b obtained with the NIRISS 13 instrument on the JWST. The data span 0.85 to 2.85 μm in wavelength at an average resolving power of 400 and exhibit minimal systematics. The spectrum shows three water emission features (at >6σ confidence) and evidence for optical opacity, possibly attributable to H−, TiO and VO (combined significance of 3.8σ). Models that fit the data require a thermal inversion, molecular dissociation as predicted by chemical equilibrium, a solar heavy-element abundance (‘metallicity’, M/H=1.03−0.51+1.11 times solar) and a carbon-to-oxygen (C/O) ratio less than unity. The data also yield a dayside brightness temperature map, which shows a peak in temperature near the substellar point that decreases steeply and symmetrically with longitude towards the terminators. © 2023, The Author(s).Ítem A Super-Earth and Sub-Neptune Transiting the Late-type M Dwarf LP 791-18(Astrophysical Journal Letters, 2019-09-20) Crossfield, Ian J. M.; Waalkes, William; Newton, Elisabeth R.; Narita, Norio; Muirhead, Philip; Ment, Kristo; Matthews, Elisabeth; Kraus, Adam; Kostov, VeselinPlanets occur most frequently around cool dwarfs, but only a handful of specific examples are known to orbit the latest-type M stars. Using TESS photometry, we report the discovery of two planets transiting the low-mass star called LP 791-18 (identified by TESS as TOI 736). This star has spectral type M6V, effective temperature 2960 K, and radius 0.17 R o, making it the third-coolest star known to host planets. The two planets straddle the radius gap seen for smaller exoplanets; they include a 1.1R ⊕ planet on a 0.95 day orbit and a 2.3R ⊕ planet on a 5 day orbit. Because the host star is small the decrease in light during these planets' transits is fairly large (0.4% and 1.7%). This has allowed us to detect both planets' transits from ground-based photometry, refining their radii and orbital ephemerides. In the future, radial velocity observations and transmission spectroscopy can both probe these planets' bulk interior and atmospheric compositions, and additional photometric monitoring would be sensitive to even smaller transiting planets.Ítem Early Release Science of the exoplanet WASP-39b with JWST NIRISS(Nature Research, 2023-02) Feinstein, Adina D.; Radica, Michael; Welbanks, Luis; Murray, Catriona Anne; Ohno, Kazumasa; Coulombe, Louis-Philippe; Espinoza, Néstor; Bean, Jacob L.; Teske, Johanna K.; Benneke, Björn; Line, Michael R.; Rustamkulov, Zafar; Saba, Arianna; Tsiaras, Angelos; Barstow, Joanna K.; Fortney, Jonathan J.; Gao, Peter; Knutson, Heather A.; MacDonald, Ryan J.; Mikal-Evans, Thomas; Rackham, Benjamin V.; Taylor, Jake; Parmentier, Vivien; Batalha, Natalie M.; Berta-Thompson, Zachory K.; Carter, Aarynn L.; Changeat, Quentin; dos Santos, Leonardo A.; Gibson, Neale P.; Goyal, Jayesh M.; Kreidberg, Laura; López-Morales, Mercedes; Lothringer, Joshua D.; Miguel, Yamila; Molaverdikhani, Karan; Moran, Sarah E.; Morello, Giuseppe; Mukherjee, Sagnick; Sing, David K.; Stevenson, Kevin B.; Wakeford, Hannah R.; Ahrer, Eva-Maria; Alam, Munazza K.; Alderson, Lili; Allen, Natalie H.; Batalha, Natasha E.; Bell, Taylor J.; Blecic, Jasmina; Brande, Jonathan; Caceres, Claudio; Casewell S.L.; Chubb, Katy L.; Crossfield, Ian J. M.; Crouzet, Nicolas; Cubillos, Patricio E.; Decin, Leen; Désert, Jean-Michel; Harrington, Joseph; Heng, Kevin; Henning, Thomas; Iro, Nicolas; Kempton, Eliza M.-R.; Kendrew, Sarah; Kirk, James; Krick, Jessica; Lagage, Pierre-Olivier; Lendl, Monika; Mancini, Luigi; Mansfield, Megan; May E.M.; Mayne N.J.; Nikolov, Nikolay K.; Palle, Enric; Petit dit de la Roche, Dominique J. M.; Piaulet, Caroline; Powell, Diana; Redfield, Seth; Rogers, Laura K.; Roman, Michael T.; Roy, Pierre-Alexis; Nixon, Matthew C.; Schlawin, Everett; Tan, Xianyu; Tremblin P.; Turner, Jake D.; Venot, Olivia; Waalkes, William C.; Wheatley, Peter J.; Zhang, XiThe Saturn-mass exoplanet WASP-39b has been the subject of extensive efforts to determine its atmospheric properties using transmission spectroscopy1–4. However, these efforts have been hampered by modelling degeneracies between composition and cloud properties that are caused by limited data quality5–9. Here we present the transmission spectrum of WASP-39b obtained using the Single-Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST. This spectrum spans 0.6–2.8 μm in wavelength and shows several water-absorption bands, the potassium resonance doublet and signatures of clouds. The precision and broad wavelength coverage of NIRISS/SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favouring a heavy-element enhancement (‘metallicity’) of about 10–30 times the solar value, a sub-solar carbon-to-oxygen (C/O) ratio and a solar-to-super-solar potassium-to-oxygen (K/O) ratio. The observations are also best explained by wavelength-dependent, non-grey clouds with inhomogeneous coverageof the planet’s terminator. © 2023, The Author(s).Ítem Sulfur dioxide in the mid-infrared transmission spectrum of WASP-39b(Nature Research, 2024-12) Powell, Diana; Feinstein, Adina D.; Lee, Elspeth K. H.; Zhang, Michael; Tsai, Shang-Min; Taylor, Jake; Kirk, James; Bell, Taylor; Barstow, Joanna; Gao, Peter; Bean, Jacob; Blecic, Jasmina; Chubb, Katy L.; Crossfield, Ian J. M.; Jordan, Sean; Kitzmann, Daniel; Moran, Sarah E.; Morello, Giuseppe; Moses, Julianne; Welbanks, Luis; Yang, Jeehyun; Zhang, Xi; Ahrer, Eva-Maria; Bello-Arufe, Aaron; Brande, Jonathan; Casewell S.L.; Crouzet, Nicolas; Cubillos, Patricio E.; Demory, Brice-Olivier; Dyrek, Achrène; Flagg, Laura; Hu, Renyu; Inglis, Julie; Jones, Kathryn D.; Kreidberg, Laura; López-Morales, Mercedes; Lagage, Pierre-Olivier; Meier Valdés, Erik A.; Miguel, Yamila; Parmentier, Vivien; Piette, Anjali A. A.; Rackham, Benjamin V.; Radica, Michael; Redfield, Seth; Stevenson, Kevin B.; Wakeford, Hannah R.; Aggarwal, Keshav; Alam, Munazza K.; Batalha, Natalie M.; Batalha, Natasha E.; Benneke, Björn; Berta-Thompson, Zach K.; Brady, Ryan P.; Caceres, Claudio; Carter, Aarynn L.; Désert, Jean-Michel; Harrington, Joseph; Iro, Nicolas; Line, Michael R.; Lothringer, Joshua D.; MacDonald, Ryan J.; Mancini, Luigi; Molaverdikhani, Karan; Mukherjee, Sagnick; Nixon, Matthew C.; Oza, Apurva V.; Palle, Enric; Rustamkulov, Zafar; Sing, David K.; Steinrueck, Maria E.; Venot, Olivia; Wheatley, Peter J.; Yurchenko, Sergei N.The recent inference of sulfur dioxide (SO2) in the atmosphere of the hot (approximately 1,100 K), Saturn-mass exoplanet WASP-39b from near-infrared JWST observations1–3 suggests that photochemistry is a key process in high-temperature exoplanet atmospheres4. This is because of the low (<1 ppb) abundance of SO2 under thermochemical equilibrium compared with that produced from the photochemistry of H2O and H2S (1–10 ppm)4–9. However, the SO2 inference was made from a single, small molecular feature in the transmission spectrum of WASP-39b at 4.05 μm and, therefore, the detection of other SO2 absorption bands at different wavelengths is needed to better constrain the SO2 abundance. Here we report the detection of SO2 spectral features at 7.7 and 8.5 μm in the 5–12-μm transmission spectrum of WASP-39b measured by the JWST Mid-Infrared Instrument (MIRI) Low Resolution Spectrometer (LRS)10. Our observations suggest an abundance of SO2 of 0.5–25 ppm (1σ range), consistent with previous findings4. As well as SO2, we find broad water-vapour absorption features, as well as an unexplained decrease in the transit depth at wavelengths longer than 10 μm. Fitting the spectrum with a grid of atmospheric forward models, we derive an atmospheric heavy-element content (metallicity) for WASP-39b of approximately 7.1–8.0 times solar and demonstrate that photochemistry shapes the spectra of WASP-39b across a broad wavelength range.