Mu Arae d

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Mu Arae d
Exoplanet List of exoplanets
Parent star
Star Mu Arae
Constellation Ara
Right ascension (α) 17h 44m 08.7s
Declination (δ) −51° 50′ 03″
Apparent magnitude (mV) 5.15
Distance 50.6 ± 0.2 ly
(15.51 ± 0.07 pc)
Spectral type G3IV–V
Mass (m) 1.10 ± 0.01 M
Radius (r) 1.36 ± 0.01 R
Temperature (T) 5820 ± 40 K
Metallicity [Fe/H] 0.30 ± 0.01
Age 6.34 ± 0.40 Gyr
Orbital elements
Semi-major axis (a) 0.9210[1] AU
(137.78 Gm)
Periastron (q) 0.8597 AU
(128.61 Gm)
Apastron (Q) 0.9823 AU
(146.96 Gm)
Eccentricity (e) 0.0666 ± 0.0122[1]
Orbital period (P) 310.55 ± 0.83[1] d
(0.8502 y)
Argument of
(ω) 189.6 ± 9.4[1]°
Time of periastron (T0) 2452708.7 ± 8.3[1] JD
Semi-amplitude (K) 14.91 ± 0.59[1] m/s
Physical characteristics
Minimum mass (m sin i) 0.5219[1] MJ
(165.9[1] M)
Discovery information
Discovery date August 5, 2006
Discoverer(s) Goździewski et al.
Mayor, Pepe
Discovery method Doppler Spectroscopy
Discovery site  Chile, South America
Discovery status Published
Other designations
Rocinante, HD 160691 d
Database references
Extrasolar Planets
Exoplanet Archive data
Open Exoplanet Catalogue data

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

In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars.[2] The process involved public nomination and voting for the new names.[3] In December 2015, the IAU announced the winning name was Rocinante for this planet.[4] 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.[5]

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.[6] Furthermore, given its mass, the planet is likely to be a gas giant with no solid surface.


  1. ^ a b c d e f g h 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/0608396free to read. Bibcode:2007A&A...462..769P. doi:10.1051/0004-6361:20066194. 
  2. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. 9 July 2014
  3. ^ NameExoWorlds The Process
  4. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  5. ^ NameExoWorlds The Approved Names
  6. ^ Buccino, A.; et al. (2006). "Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones". Icarus. 183 (2): 491–503. arXiv:astro-ph/0512291free to read. doi:10.1016/j.icarus.2006.03.007. 

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