WASP-121b / Tylos
Artist's impression of WASP-121b and its host star
Discovery[1]
Discovered byL. Delrez et al.
Discovery date2015
Transit
Designations
Tylos[2]
Orbital characteristics[3]
0.02596+0.00043
−0.00063 AU
Eccentricity<0.0032
1.27492504(15) d
Inclination88.49°±0.16°
10°±10°
StarWASP-121
Physical characteristics[3]
Mean radius
1.753±0.036 RJ
Mass1.157±0.070 MJ
Mean density
0.266+0.024
−0.022 g/cm3
9.33+0.71
−0.67 m/s2 (0.95 g)
Temperature2602±53 K (2,329 °C; 4,224 °F)[4]

    WASP-121b, formally named Tylos,[2] is an exoplanet orbiting the star WASP-121.[5][6] WASP-121b is the first exoplanet found to contain water in an extrasolar planetary stratosphere (i.e., an atmospheric layer in which temperatures increase as the altitude increases).[5][6] WASP-121b is in the constellation Puppis,[7] and is about 858 light-years from Earth.[8][5][9]

    Nomenclature

    In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project.[10] The approved names, proposed by a team from Bahrain, were announced in June 2023. WASP-121b is named Tylos after the ancient Greek name for Bahrain, and its host star is named Dilmun after the ancient civilization.[2]

    Characteristics

    WASP-121b - computer simulated views (August 2018)

    WASP-121b is a hot Jupiter exoplanet with a mass about 1.16 times that of Jupiter and a radius about 1.75 times that of Jupiter. The exoplanet orbits WASP-121, its host star, every 1.27 days.[3]

    In 2019 a work by Hellard et al. discussed the possibility of measuring the Love number of transiting hot Jupiters using HST/STIS. A tentative measurement of for WASP-121b was published in the same work.[11][12]

    The planetary orbit is inclined to the equatorial plane of the star by 8.1°.[13]

    Atmospheric composition

    A spectral survey in 2015 attributed 2,500 °C (4,530 °F), hot[5] stratosphere absorption bands to water molecules, titanium(II) oxide (TiO) and vanadium(II) oxide (VO).[14] Neutral iron was also detected in the stratosphere of WASP-121b in 2020,[15][16] along with neutral chromium and vanadium.[17] The detection claims of titanium(II) oxide (TiO) and vanadium(II) oxide (VO) have since been disproved.[6][18][19][20]

    Reanalysis of aggregated spectral data was published in June 2020. Neutral magnesium, calcium, vanadium, chromium, iron, and nickel, along with ionized sodium atoms, were detected. The low quality of available data preclude a positive identification of any molecular species, including water. The atmosphere appears to be significantly out of chemical equilibrium and possibly escaping.[21] The strong atmospheric flows beyond the Roche lobe, indicating ongoing atmosphere loss, were confirmed in late 2020.[13]

    In 2021, the planetary atmosphere turned out to be slightly more blue and less absorbing, which may be an indication of planetary weather patterns.[22] By mid-2021, the presence of ions of iron, chromium, vanadium and calcium in the planetary atmosphere was confirmed.[23] In 2022, barium was also detected.[24] By 2022, an absence of titanium in the planetary atmosphere was confirmed and attributed to the nightside condensation of highly refractory titanium dioxide.[25]

    Observations by the Hubble Space Telescope from 2016-2019, published in 2024, confirm variability in the atmosphere of WASP-121b.[26][27]

    Possible exomoon

    The sodium detected via absorption spectroscopy around WASP-121b[21] is consistent with an extrasolar gas torus, possibly fueled by a hidden exo-Io.[28]

    See also

    Wikimedia Commons has media related to WASP-121 b.

    References

    1. ↑ Delrez, L.; Santerne, A.; Almenara, J.-M.; Anderson, D. R.; Collier-Cameron, A.; Díaz, R. F.; Gillon, M.; Hellier, C.; Jehin, E.; Lendl, M.; Maxted, P. F. L.; Neveu-Vanmalle, M.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Smalley, B.; Smith, A. M. S.; Triaud, A. H. M. J.; Udry, S.; Van Grootel, V.; West, R. G. (2015), "WASP-121 b: A hot Jupiter close to tidal disruption transiting an active F star", Monthly Notices of the Royal Astronomical Society, 458 (4): 4025–4043, arXiv:1506.02471, Bibcode:2016MNRAS.458.4025D, doi:10.1093/mnras/stw522
    2. 1 2 3 "2022 Approved Names". nameexoworlds.iau.org. IAU. Retrieved 7 June 2023.
    3. 1 2 3 Bourrier, V.; Ehrenreich, D.; et al. (March 2020). "Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS). III. Atmospheric structure of the misaligned ultra-hot Jupiter WASP-121b". Astronomy & Astrophysics. 635: A205. arXiv:2001.06836. Bibcode:2020A&A...635A.205B. doi:10.1051/0004-6361/201936640.
    4. ↑ Changeat, Q.; Edwards, B.; et al. (May 2022). "Five Key Exoplanet Questions Answered via the Analysis of 25 Hot-Jupiter Atmospheres in Eclipse". The Astrophysical Journal Supplement Series. 260 (1): 3. arXiv:2204.11729. Bibcode:2022ApJS..260....3C. doi:10.3847/1538-4365/ac5cc2.
    5. 1 2 3 4 Landau, Elizabeth; Villard, Ray (2 August 2017). "Hubble Detects Exoplanet with Glowing Water Atmosphere". NASA. Retrieved 2 August 2017.
    6. 1 2 3 Evans, Thomas M.; Sing, David K.; et al. (2 August 2017). "An ultrahot gas-giant exoplanet with a stratosphere". Nature. 548 (7665): 58–61. arXiv:1708.01076. Bibcode:2017Natur.548...58E. doi:10.1038/nature23266. ISSN 1476-4687. PMID 28770846. S2CID 205258293.
    7. ↑ Staff. "Finding the constellation which contains given sky coordinates". djm.cc. Retrieved 3 August 2017.
    8. ↑ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
    9. ↑ Greicius, Tony (7 August 2018). "Water Is Destroyed, Then Reborn in Ultrahot Jupiters". NASA. Retrieved 15 November 2018.
    10. ↑ "List of ExoWorlds 2022". nameexoworlds.iau.org. IAU. 8 August 2022. Retrieved 27 August 2022.
    11. ↑ Hellard, Hugo; Csizmadia, Szilárd; Padovan, Sebastiano; Sohl, Frank; Rauer, Heike (2020). "HST/STIS capability for Love number measurement of WASP-121b". The Astrophysical Journal. 889 (1): 66. arXiv:1912.05889. Bibcode:2020ApJ...889...66H. doi:10.3847/1538-4357/ab616e. S2CID 209324250.
    12. ↑ waspplanets (19 December 2019). "The tidal shape of the exoplanet WASP-121b". WASP Planets. Retrieved 20 January 2020.
    13. 1 2 Borsa, F.; et al. (2021), "Atmospheric Rossiter–Mc Laughlin effect and transmission spectroscopy of WASP-121b with ESPRESSO", Astronomy & Astrophysics, 645: A24, arXiv:2011.01245, Bibcode:2021A&A...645A..24B, doi:10.1051/0004-6361/202039344, S2CID 226237425
    14. ↑ Staff (2015). "Planet WASP-121 b". Extrasolar Planets Encyclopaedia. Retrieved 3 August 2017.
    15. ↑ Gibson, Neale P.; Merritt, Stephanie; Nugroho, Stevanus K.; Cubillos, Patricio E.; de Mooij, Ernst J. W.; Mikal-Evans, Thomas; Fossati, Luca; Lothringer, Joshua; Nikolov, Nikolay; Sing, David K.; Spake, Jessica J.; Watson, Chris A.; Wilson, Jamie (2020). "Detection of Fe I in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy". Monthly Notices of the Royal Astronomical Society. 493 (2): 2215. arXiv:2001.06430. Bibcode:2020MNRAS.493.2215G. doi:10.1093/mnras/staa228. S2CID 210714233.
    16. ↑ Cabot, Samuel H. C.; Madhusudhan, Nikku; Welbanks, Luis; Piette, Anjali; Gandhi, Siddharth (2020). "Detection of neutral atomic species in the ultra-hot jupiter WASP-121b". Monthly Notices of the Royal Astronomical Society. 494 (1): 363–377. arXiv:2001.07196. Bibcode:2020MNRAS.494..363C. doi:10.1093/mnras/staa748. S2CID 210838889.
    17. ↑ Ben-Yami, Maya; Madhusudhan, Nikku; Cabot, Samuel H. C.; Constantinou, Savvas; Piette, Anjali; Gandhi, Siddharth; Welbanks, Luis (2020). "Neutral Cr and V in the Atmosphere of Ultra-hot Jupiter WASP-121 B". The Astrophysical Journal. 897 (1): L5. arXiv:2006.05995. Bibcode:2020ApJ...897L...5B. doi:10.3847/2041-8213/ab94aa. S2CID 219573825.
    18. ↑ Mikal-Evans, Thomas (27 June 2019). "An emission spectrum for WASP-121b measured across the 0.8–1.1 μm wavelength range using the Hubble Space Telescope". Monthly Notices of the Royal Astronomical Society. 488 (2): 2222–2234. arXiv:1906.06326. Bibcode:2019MNRAS.488.2222M. doi:10.1093/mnras/stz1753. hdl:10150/634587 – via OUP.
    19. ↑ Merritt, S. R.; Gibson, N. P.; Nugroho, S. K.; Mooij, E. J. W. de; Hooton, M. J.; Matthews, S. M.; McKemmish, L. K.; Mikal-Evans, T.; Nikolov, N.; Sing, D. K.; Spake, J. J. (1 April 2020). "Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy". Astronomy & Astrophysics. 636: A117. arXiv:2002.02795. Bibcode:2020A&A...636A.117M. doi:10.1051/0004-6361/201937409. ISSN 0004-6361.
    20. ↑ Mikal-Evans, Thomas; Sing, David K.; Kataria, Tiffany; Wakeford, Hannah R.; Mayne, Nathan J.; Lewis, Nikole K.; Barstow, Joanna K.; Spake, Jessica J. (2020). "Confirmation of water emission in the dayside spectrum of the ultrahot Jupiter WASP-121b". Monthly Notices of the Royal Astronomical Society. 496 (2): 1638–1644. arXiv:2005.09631. Bibcode:2020MNRAS.496.1638M. doi:10.1093/mnras/staa1628. S2CID 218684532.
    21. 1 2 Hoeijmakers, H.J.; Seidel, J.V.; Pino, L.; Kitzmann, D.; Sindel, J.P.; Ehrenreich, D.; Oza, A.V.; Bourrier, V.; Allart, R.; Gebek, A.; Lovis, C.; Yurchenko, S.N.; Astudillo-Defru, N.; Bayliss, D.; Cegla, H.; Lavie, B.; Lendl, M.; Melo, C.; Murgas, F.; Nascimbeni, V.; Pepe, F.; Segransan, D.; Udry, S.; Wyttenbach, A.; Heng, K. (18 September 2020). "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. 641: A123. arXiv:2006.11308. Bibcode:2020A&A...641A.123H. doi:10.1051/0004-6361/202038365. S2CID 219966241.
    22. ↑ Wilson, Jamie; Gibson, Neale P.; Lothringer, Joshua D.; Sing, David K.; Mikal-Evans, Thomas; De Mooij, Ernst J W.; Nikolov, Nikolay; Watson, Chris A. (2021), "Gemini/GMOS optical transmission spectroscopy of WASP-121b: Signs of variability in an ultra-hot Jupiter?", Monthly Notices of the Royal Astronomical Society, 503 (4): 4787–4801, arXiv:2103.05698, doi:10.1093/mnras/stab797
    23. ↑ Merritt, Stephanie R.; Gibson, Neale P.; Nugroho, Stevanus K.; De Mooij, Ernst J W.; Hooton, Matthew J.; Lothringer, Joshua D.; Matthews, Shannon M.; Mikal-Evans, Thomas; Nikolov, Nikolay; Sing, David K.; Watson, Chris A. (2021), "An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy", Monthly Notices of the Royal Astronomical Society, 506 (3): 3853–3871, arXiv:2106.15394, doi:10.1093/mnras/stab1878
    24. ↑ Azevedo Silva, T.; et al. (2022), "Detection of barium in the atmospheres of the ultra-hot gas giants WASP-76b and WASP-121b", Astronomy & Astrophysics, 666: L10, arXiv:2210.06892, doi:10.1051/0004-6361/202244489, S2CID 252873126
    25. ↑ Hoeijmakers, H. J.; Kitzmann, D.; Morris, B. M.; Prinoth, B.; Borsato, N.; Pino, L.; Lee, E. K. H.; Akın, C.; Heng, K. (2022), The Mantis Network III: A titanium cold-trap on the ultra-hot Jupiter WASP-121 b., arXiv:2210.12847
    26. ↑ "Hubble observes a changing exoplanet atmosphere". esahubble.org. ESA. 4 January 2024. Retrieved 4 January 2024.
    27. ↑ Changeat, Quentin; Skinner, Jack W.; et al. (January 2024). "Is the atmosphere of the ultra-hot Jupiter WASP-121b variable?". The Astrophysical Journal Supplement Series. arXiv:2401.01465.
    28. ↑ Gebek, Andrea; Oza, Apurva (29 July 2020). "Alkaline exospheres of exoplanet systems: evaporative transmission spectra". Monthly Notices of the Royal Astronomical Society. 497 (4): 5271–5291. arXiv:2005.02536. Bibcode:2020MNRAS.497.5271G. doi:10.1093/mnras/staa2193. S2CID 218516741. Retrieved 8 December 2020.
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