Gliese 3470 b
|Exoplanet||List of exoplanets|
Size comparison of Gliese 3470 b with Earth.
|Right ascension||(α)||07h 59m 0.60s|
|Declination||(δ)||+15° 23′ 30″|
|Density||(ρ)||±0.33 1.18g cm−3|
|Semi-major axis||(a)||±0.0028 0.031AU|
|Discoverer(s)||X. Bonfils et. al |
|Discovery method||Radial velocity|
Gliese 3470 b, abbreviated as GJ3470b, is an exoplanet orbiting the star Gliese 3470, both of which are located in the constellation Cancer. With a mass of just under 14 Earth-masses and a radius approximately 4.3 times that of Earth's, it is likely something akin to a mini-Neptune despite the initially strong belief that the planet was not covered in clouds like the gas giants we are familiar with in our solar system. 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." Recently in 2015, a team using the Las Cumbres Observatory Global Telescope (LCOGT) network reported their detection of Rayleigh scattering in the atmosphere of this planet. 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. It is thought that the planet would appear blue to the human eye due to this scattering. As of now, GJ3470b is the only exoplanet orbiting the Gliese 3470 star that has been observed and analyzed by astronomers and astrophysicists.
On December 15th 2018, astronomers discovered that the planet's atmosphere is evaporating. The stated reason for why astronomers think that the planet is evaporating is that the planet is predicted to be 90% closer to the star Gliese 3470 in distance, than compared to the distance of the planet Mercury to Sun in our Solar System. Because of this the predicted temperature of the planet at which it is evaporating away is said to be at approximately 1700F. The predicted evaporation rate is also theorized to be "3 times faster than that of the last evaporating exoplanet that was discovered." It is also predicted that if any liquid vapors are present in the atmosphere they boil away. Once the atmosphere is evaporated only its possibly rocky core would remain. 
Artist's impression of gas streaming from GJ 3470b.
- Bonfils, X; Gillon, M; Udry, S; Armstrong, D; Bouchy, F; Delfosse, X; Forveille, T; Jehin, E; Lendl, M; Lovis, C; Mayor, M; McCormac, J; Neves, V; Pepe, F; Perrier, C; Pollaco, D; Queloz, D; Santos, N. C; Santos, N. 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.
- 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.
- 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.
- "Astronomers discover 'evaporating' planet". USA TODAY. 15 December 2018. Retrieved 16 December 2018.
- "Artist's impression of gas streaming from GJ 3470b". www.spacetelescope.org. Retrieved 17 December 2018.
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