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GJ 3470 b

GJ 3470 b (occasionally Gliese 3470 b, formally named Phailinsiam[2]) is an exoplanet orbiting the star GJ 3470, located in the constellation Cancer. With a mass of just under 14 Earth-masses, a radius approximately 4.3 times that of Earth's, and a high equilibrium temperature of 615 K (342 °C; 647 °F),[4] it is a hot Neptune.

GJ 3470 b / Phailinsiam
Size comparison of Phailinsiam with Earth.
Discovery[1]
Discovered byX. Bonfils et al.
Discovery date2012
Radial velocity
Designations
Phailinsiam[2]
Orbital characteristics[3]
0.0355±0.0019 AU
Eccentricity0.114+0.052
−0.051[4]
3.33665240(14) d[5]
Inclination89.13°+0.26°
−0.34°
StarGJ 3470
Physical characteristics[3]
4.57±0.18 R🜨
Mass13.9±1.5 M🜨
Mean density
0.80±0.13 g/cm3
Temperature615±16 K[4]

The orbit of GJ 3470 b is strongly inclined to the equatorial plane of the parent star, with misalignment equal to 97+16
−11°.[6]

Nomenclature

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In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project.[7] The approved names, proposed by a team from Thailand, were announced in June 2023. GJ 3470 b is named Phailinsiam and its host star is named Kaewkosin, after names of precious stones in the Thai language.[2]

Atmosphere

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The atmosphere of Phailinsiam is one of the best spectroscopically characterized among all exoplanets.

The exoplanet's atmosphere was first observed by researchers Akihiko Fukui, Norio Narita and Kenji Kuroda at the University of Tokyo in 2013, and afterwards, Fukui commented, "Suppose the atmosphere consists of hydrogen and helium, the mass of the atmosphere would be 5–20% of the total mass of the planet. Comparing that to the fact that the mass of Earth's atmosphere is about one ten-thousandth of a percent (0.0001%) of the total mass of the Earth, this planet has a considerably thick atmosphere."[8] In 2013, by means of Large Binocular Telescope observations, with the LBC Blue and Red cameras, a team reported the detection of Rayleigh scattering in the atmosphere of this planet.[9] In 2015 a team using the Las Cumbres Observatory Global Telescope (LCOGT) network confirmed this finding. In the Las Cumbres researchers' paper published in The Astrophysical Journal, they conclude that the most plausible explanation for the scattering effect to be an atmosphere made predominantly of hydrogen and helium, causing the exoplanet to be veiled by dense clouds and hazes.[10] It is thought that the planet would appear blue to the human eye due to this scattering.

In 2017–2019, the primary hydrogen atmosphere with overall low metallicity, depleted methane and traces of water was characterized.[11][12] It is likely filling an entire Roche lobe of the planet.[13] In 2019 and 2020, a metastable helium outflow was detected in the atmosphere of Phailinsiam, indicating the atmosphere is currently escaping at rate 30,000-100,000 tons per second, or 0.16-0.53 Earth masses per billion years.[14][15]

In 2024, astronomers discovered a haze of sulfur dioxide in the atmosphere of the exoplanet indicating active chemical reactions in the atmosphere, likely triggered by radiation from its nearby star.[16]

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  •  
    Structure of Exoplanet GJ 3470 b.[17]
  •  
    Artist's impression of gas streaming from GJ 3470b.[18]

See also

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References

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  1. ^ Bonfils, Xavier; Gillon, Michaël; Udry, Stéphane; Armstrong, David; Bouchy, François; Delfosse, Xavier; Forveille, Thierry; Fumel, Aurélie; Jehin, Emmanuël; Lendl, Monika; Lovis, Christophe; Mayor, Michel; McCormac, James; Neves, Vasco; Pepe, Francesco; Perrier, Christian; Pollacco, Don L.; Queloz, Didier; Santos, Nuno C. (2012). "A hot Uranus transiting the nearby M dwarf GJ3470. Detected with HARPS velocimetry. Captured in transit with TRAPPIST photometry". Astronomy & Astrophysics. 546: A27. arXiv:1206.5307. Bibcode:2012A&A...546A..27B. doi:10.1051/0004-6361/201219623. S2CID 12963626.
  2. ^ a b c "2022 Approved Names". nameexoworlds.iau.org. IAU. Retrieved 7 June 2023.
  3. ^ a b Awiphan, S.; Kerins, E.; et al. (December 2016). "Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b". Monthly Notices of the Royal Astronomical Society. 463 (3): 2574–2582. arXiv:1606.02962. Bibcode:2016MNRAS.463.2574A. doi:10.1093/mnras/stw2148.
  4. ^ a b c Kosiarek, Molly R.; Crossfield, Ian J. M.; et al. (March 2019). "Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits". The Astronomical Journal. 157 (3): 97. arXiv:1812.08241. Bibcode:2019AJ....157...97K. doi:10.3847/1538-3881/aaf79c. S2CID 119440420.
  5. ^ Kokori, A.; et al. (14 February 2023). "ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations". The Astrophysical Journal Supplement Series. 265 (1) 4. arXiv:2209.09673. Bibcode:2023ApJS..265....4K. doi:10.3847/1538-4365/ac9da4. Vizier catalog entry
  6. ^ Stefànsson, Guđmundur; et al. (2022). "The Warm Neptune GJ 3470b Has a Polar Orbit". The Astrophysical Journal Letters. 931 (2): L15. arXiv:2111.01295. Bibcode:2022ApJ...931L..15S. doi:10.3847/2041-8213/ac6e3c. S2CID 240419664.
  7. ^ "List of ExoWorlds 2022". nameexoworlds.iau.org. IAU. 8 August 2022. Retrieved 27 August 2022.
  8. ^ Fukui, Akihiko; et al. (2013). "Optical-to-Near-Infrared Simultaneous Observations for the Hot Uranus GJ3470b: A Hint for Cloud-free Atmosphere". The Astrophysical Journal. 770 (2): 95. arXiv:1302.7257. Bibcode:2013ApJ...770...95F. doi:10.1088/0004-637X/770/2/95. S2CID 119118506.
  9. ^ Nascimbeni, Valerio; Piotto, Giampaolo; Pagano, Isabella; Scandariato, Gaetano; Sani, Eleonora; Fumana, M. (2013). "The blue sky of GJ3470b: the atmosphere of a low-mass planet unveiled by ground-based photometry". Astronomy and Astrophysics. 559: A32. arXiv:1308.6765. Bibcode:2013A&A...559A..32N. doi:10.1051/0004-6361/201321971. S2CID 118497221.
  10. ^ Dragomir, Diana; et al. (2015). "Rayleigh Scattering in the Atmosphere of the Warm Exo-Neptune GJ 3470b". The Astrophysical Journal. 814 (2): 9. arXiv:1511.05601. Bibcode:2015ApJ...814..102D. doi:10.1088/0004-637X/814/2/102. S2CID 26425223.
  11. ^ Chen, G.; Guenther, E. W.; Pallé, E.; Nortmann, L.; Nowak, G.; Kunz, S.; Parviainen, H.; Murgas, F. (2017). "The GTC exoplanet transit spectroscopy survey". Astronomy & Astrophysics. 600: A138. arXiv:1703.01817. Bibcode:2017A&A...600A.138C. doi:10.1051/0004-6361/201630228. S2CID 119269112.
  12. ^ Benneke, Björn; Knutson, Heather A.; Lothringer, Joshua; Crossfield, Ian J.M.; Moses, Julianne I.; Morley, Caroline; Kreidberg, Laura; Fulton, Benjamin J.; Dragomir, Diana; Howard, Andrew W.; Wong, Ian; Désert, Jean-Michel; McCullough, Peter R.; Kempton, Eliza M.-R.; Fortney, Jonathan; Gilliland, Ronald; Deming, Drake; Kammer, Joshua (2019). "A sub-Neptune exoplanet with a low-metallicity methane-depleted atmosphere and Mie-scattering clouds". Nature Astronomy. 3 (9): 813–821. arXiv:1907.00449. Bibcode:2019NatAs...3..813B. doi:10.1038/s41550-019-0800-5. S2CID 256707037.
  13. ^ Bourrier, V.; Lecavelier Des Etangs, A.; Ehrenreich, D.; Sanz-Forcada, J.; Allart, R.; Ballester, G. E.; Buchhave, L. A.; Cohen, O.; Deming, D.; Evans, T. M.; García Muñoz, A.; Henry, G. W.; Kataria, T.; Lavvas, P.; Lewis, N.; López-Morales, M.; Marley, M.; Sing, D. K.; Wakeford, H. R. (2018). "Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b". Astronomy & Astrophysics. 620: A147. arXiv:1812.05119. Bibcode:2018A&A...620A.147B. doi:10.1051/0004-6361/201833675. S2CID 239583863.
  14. ^ Pallé, E.; Nortmann, L.; Casasayas-Barris, N.; Lampón, M.; López-Puertas, M.; Caballero, J. A.; Sanz-Forcada, J.; Lara, L. M.; Nagel, E.; Yan, F.; Alonso-Floriano, F. J.; Amado, P. J.; Chen, G.; Cifuentes, C.; Cortés-Contreras, M.; Czesla, S.; Molaverdikhani, K.; Montes, D.; Passegger, V. M.; Quirrenbach, A.; Reiners, Ansgar; Ribas, I.; Sánchez-López, A.; Schweitzer, A.; Stangret, M.; Zapatero-Osorio, María Rosa; Zechmeister, M. (2020). "A He I upper atmosphere around the warm Neptune GJ 3470 B". Astronomy & Astrophysics. 638: A61. arXiv:2004.12812. Bibcode:2020A&A...638A..61P. doi:10.1051/0004-6361/202037719. S2CID 216553362.
  15. ^ Ninan, Joe P.; Stefansson, Gudmundur; Mahadevan, Suvrath; Bender, Chad; Robertson, Paul; Ramsey, Lawrence; Terrien, Ryan; Wright, Jason; Diddams, Scott A.; Kanodia, Shubham; Cochran, William; Endl, Michael; Ford, Eric B.; Fredrick, Connor; Halverson, Samuel; Hearty, Fred; Jennings, Jeff; Kaplan, Kyle; Lubar, Emily; Metcalf, Andrew J.; Monson, Andrew; Nitroy, Colin; Roy, Arpita; Schwab, Christian (2019). "Evidence for He i 10830 Å Absorption during the Transit of a Warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder". The Astrophysical Journal. 894 (2): 97. arXiv:1910.02070. Bibcode:2020ApJ...894...97N. doi:10.3847/1538-4357/ab8559. S2CID 203737369.
  16. ^ "Small, cool and sulfurous exoplanet may help write recipe for planetary formation".
  17. ^ "Structure of Exoplanet GJ 3470 b". www.spacetelescope.org. Retrieved 5 July 2019.
  18. ^ "Artist's impression of gas streaming from GJ 3470b". www.spacetelescope.org. Retrieved 17 December 2018.
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