Astronomy:51 Eridani b

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Short description: Extrasolar planet
51 Eri b
51 Eridani b orbit animated (2014-2018).gif
Direct imaging of 51 Eri b
Discovery
Discovered byMacintosh et al.
Discovery dateDec 2014
Imaged
Orbital characteristics
11.1+4.2
−1.3 AU
Eccentricity0.49 (± 0.15) [1]
Orbital period10260+6300
−1800 d
Inclination136.0 (± 11.0) [1] deg
astron|astron|helion}}2452014.79 (± 12.0) [1] JD
84.0 (± 58.0) [1] deg
Star51 Eridani
Physical characteristics
Mean radius1.11+0.16
−0.13 |♃|J}}}}}}
Mass2.6 (± 0.3) |♃|J}}}}}}
3.5 g
Physics700 K[2]


51 Eridani b is a "Jupiter-like" planet that orbits the young F0 V star 51 Eridani, in the constellation Eridanus.[3] It is 96 light years away from the solar system, and it is approximately 20 million years old.[4]

Discovery

51 Eridani b was announced in August 2015, but was discovered in December 2014 using the Gemini Planet Imager, an international project led by the Kavli Institute for Particle Astrophysics and Cosmology. 51 Eridani b is the first exoplanet discovered by the Gemini Planet Imager.[5] The Gemini Planet Imager was specifically created to discern and evaluate dim, newer planets orbiting bright stars through “direct imaging.”[6] Direct imaging allows astronomers to use adaptive optics to sharpen the resolution of the image of a target star, then obstruct its starlight.[6] Any residual incoming light is then scrutinized, and the brightest spots suggest a possible planet.[6] Prior to the discovery of 51 Eridani b, each of the directly imaged worlds previously discovered had been gas giants many times the mass of Jupiter.[7]

Physical characteristics

The planet has a mass at least 2.6MJ, but not more than 11MJ.[8] Its radius is about 1.11 times the radius of Jupiter. It orbits 11.1 AU from its host star, and has an orbital period of roughly 10,000 days.[1] The average temperature is 807±45 K, which is substantially hotter than the 130 K average temperature of Jupiter, the planet in the Solar System of closest size.[9]

Atmosphere

51 Eridani b has relatively low C/O molar ratio of 0.38±0.09.[9] The planet has the second strongest methane signature of any exoplanet, after GJ 504 b.[10] This methane signature, along with the low luminosity of the object, should produce additional clues as to how 51 Eridani b was formed.[5] Astronomers also detected the presence of water[11] and ammonia[12] in the planet's spectrum. Atmospheric modeling favors a low surface gravity and a partly cloudy atmosphere.[7]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 "Planet 51 Eri b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/51_eri_b--2428/. 
  2. ↑ Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager, B. Macintosh, and the GPIES team, Science Published Online August 13, 2015 doi:10.1126/science.aac5891.
  3. ↑ Choi, Charles (August 13, 2015). "Found! 'Young Jupiter,' the Smallest Exoplanet Directly Seen by Telescope". http://www.space.com/30248-young-jupiter-smallest-directly-imaged-exoplanet.html. 
  4. ↑ Hadhazy, Adam (August 13, 2015). "'Young Jupiter' 51 Eridani b: Why Directly Imaging an Exoplanet Is Big". space.com. http://www.space.com/30238-young-jupiter-exoplanet-51-eridani-b-explained.html. 
  5. ↑ 5.0 5.1 University, Stanford (13 August 2015). "Astronomers discover 'young Jupiter' exoplanet". http://news.stanford.edu/news/2015/august/exoplanet-macintosh-eridani-081315.html. 
  6. ↑ 6.0 6.1 6.2 Culler, Jessica (14 August 2015). "NASA Scientists Help Understand Newly Discovered Planet". http://www.nasa.gov/feature/ames/nasa-scientists-help-understand-newly-discovered-planet. 
  7. ↑ 7.0 7.1 Billings, Lee. "Astronomers Glimpse a Young Jupiter, 51 Eridani b". http://www.scientificamerican.com/article/astronomers-glimpse-a-young-jupiter-51-eridani-b/. 
  8. ↑ Dupuy, Trent J.; Brandt, G Mirek; Brandt, Timothy D. (2022), "Limits on the mass and initial entropy of 51 Eri b from Gaia EDR3 astrometry", Monthly Notices of the Royal Astronomical Society 509 (3): 4411–4419, doi:10.1093/mnras/stab3148 
  9. ↑ 9.0 9.1 Brown-Sevilla, S. B.; Maire, A. -L.; Mollière, P.; Samland, M.; Feldt, M.; Brandner, W.; Henning, Th.; Gratton, R. et al. (2023), "Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE", Astronomy & Astrophysics 673: A98, doi:10.1051/0004-6361/202244826, Bibcode: 2023A&A...673A..98B 
  10. ↑ "Astronomers Discover Young Planet That Looks Like Jupiter 100 Light Years Away". 13 August 2015. https://www.independent.co.uk/news/science/51-eridani-b-astronomers-discover-young-planet-that-looks-like-jupiter-100-light-years-away-10454531.html%7Cdate. [|permanent dead link|dead link}}]
  11. ↑ "Young 'alien Jupiter' discovered". BBC News. 14 August 2015. https://www.bbc.co.uk/news/science-environment-33922503. 
  12. ↑ Whiteford, Niall; Glasse, Alistair; Chubb, Katy L.; Kitzmann, Daniel; Ray, Shrishmoy; Phillips, Mark W.; Biller, Beth A.; Palmer, Paul I. et al. (2023), "Retrieval study of cool directly imaged exoplanet 51 Eri B", Monthly Notices of the Royal Astronomical Society 525: 1375–1400, doi:10.1093/mnras/stad670 



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