Mu Arae d

Mu Arae d, also known as HD 160691 d, formally named Rocinante /ˌrɒsəˈnænt/, is an extrasolar planet orbiting the star Mu Arae of the constellation Ara.

Mu Arae d
Discovered byGoździewski et al.
Mayor, Pepe
Discovery siteChile South America
Discovery dateAugust 5, 2006
Doppler Spectroscopy
Orbital characteristics
Apastron0.9823 AU (146,950,000 km)
Periastron0.8597 AU (128,610,000 km)
0.9210 AU (137,780,000 km)[1]
Eccentricity0.0666 ± 0.0122[1]
310.55 ± 0.83[1] d
0.8502 y
2452708.7 ± 8.3[1]
189.6 ± 9.4[1]
Semi-amplitude14.91 ± 0.59[1]
StarMu Arae


The planet has a mass about half that of Jupiter and orbits at a distance of 0.921 AU from the star with a period of 310.55 days. The planet may be located at a distance close enough to the star to receive a comparable amount of ultraviolet radiation as the Earth does from the Sun. However, it is too close to the star to be able to support liquid water at its surface.[2] Furthermore, given its mass, the planet is likely to be a gas giant with no solid surface.


In July 2014 the International Astronomical Union launched 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 winning name was Rocinante for this planet.[5] The winning name was submitted by the Planetario de Pamplona, Spain. Rocinante was the horse of the lead character of the novel El Ingenioso Hidalgo Don Quixote de la Mancha.[6]


  1. ^ a b c d e f Pepe, F.; Correia, A. C. M.; Mayor, M.; Tamuz, O.; et al. (2007). "The HARPS search for southern extra-solar planets. VIII. μ Arae, a system with four planets". Astronomy and Astrophysics. 462 (2): 769–776. arXiv:astro-ph/0608396. Bibcode:2007A&A...462..769P. doi:10.1051/0004-6361:20066194.
  2. ^ Buccino, A.; et al. (2006). "Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones". Icarus. 183 (2): 491–503. arXiv:astro-ph/0512291. Bibcode:2006Icar..183..491B. doi:10.1016/j.icarus.2006.03.007.
  3. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. 9 July 2014
  4. ^ NameExoWorlds The Process
  5. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  6. ^ NameExoWorlds The Approved Names

Coordinates:   17h 44m 08.7s, −51° 50′ 03″