18 Delphini b

18 Delphini b / Arion

Radial velocity changes over time of 18 Delphini caused by the orbit of 18 Delphini b.
Discovery
Discovered by	Sato et al.[1]
Discovery site	Okayama Planet Search Program  Japan
Discovery date	19 February 2008
Detection method	radial velocity
Orbital characteristics
Semi-major axis	2.6 AU (390,000,000 km)
Eccentricity	0.08 ± 0.01
Orbital period (sidereal)	993.3 ± 3.2 d 2.719 y
Time of periastron	2451672 ± 18
Argument of periastron	166.1 ± 6.5
Star	18 Delphini

18 Delphini b (abbreviated 18 Del b), formally named Arion /əˈraɪən/,^[2] is an extrasolar planet approximately 249 light-years away in the constellation of Delphinus.

The 993-day period planet orbits the yellow giant star 18 Delphini. A very massive and dense planet with a minimum mass of 10.3 M_J, it was discovered on February 19, 2008, by Bun'ei Sato.^[1]

In July 2014, the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.^[3] The process involved public nomination and voting for the new names.^[4] In December 2015, the IAU announced the name Arion for this planet.^[5] The winning name was submitted by the Tokushima Prefectural Jonan High School Science Club of Japan. Arion was a genius of poetry and music in ancient Greece. According to legend, his life was saved at sea by dolphins after attracting their attention by the playing of his kithara^[6] ('Delphinus' is Latin for 'dolphin').

See also

• 41 Lyncis b
• Xi Aquilae b

References

1. Sato, Bun'ei; et al. (2008). "Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae and HD 81688". Publications of the Astronomical Society of Japan. 60 (3): 539–550. arXiv:0802.2590. Bibcode:2008PASJ...60..539S. doi:10.1093/pasj/60.3.539.
2. "Arion". Merriam-Webster.com Dictionary. Merriam-Webster.
3. NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
4. "NameExoWorlds The Process". Archived from the original on 2015-08-15. Retrieved 2015-09-05.
5. Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
6. "NameExoWorlds The Approved Names". Archived from the original on 2018-02-01. Retrieved 2015-12-17.

• Jean Schneider (2011). "Notes for Planet 18 Del b". Extrasolar Planets Encyclopaedia. Retrieved 30 September 2011.

External links

• da Silva, L.; et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics, 458 (2): 609–623, arXiv:astro-ph/0608160, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105, S2CID 9341088 – lists data about the star.