Saturday, November 14, 2009

Mu Arae

Star type
g G5 V

Distance from Earth
g 49.8 ly

Star Service No.
g NA

g NA

Diameter/Mass/Temp (xSol)
g 102%; 108% (+/- 5%); NA

Brightness (xSol)
g 181%

Metallicity (xSol)
g 180%-190%

Comparison to Sol
g NA

Picture of star
g NA

Star system features
g NA

Known planets
Three planets orbit the star:
g Mu Arae d: In a very hot but circular, inner orbit (e~0), the planet is estimated to have about 14 times the mass of Earth. Located at only 0.09 AUs from the star (less than one fourth of Mercury's orbital distance from Sol), the planet competes an orbit in 9.64 days and may have a surface temperature of 1,160° Fahrenheit (900° Kevin). Under the most likely planetary developmental scenario of an inner migration from around 3 AUs under the influence of outer giant planet "b" now at 1.5 AUs, this planet is likely to have an "essentially rocky core" with an atmosphere of 5-10 percent of its total mass. For a while, this planet was called "Mu Arae c" by those unaware of the now confirmed "c" candidate.
g Mu Arae e: At 52.19% of Jupiter's mass, this planet has an average orbital distance of about 0.921 AUs. It has a relatively circular orbit (e= 0.0666 ± 0.0122) which takes about 310.55 ± 0.83 days (85 percent of an Earth year) to complete.
g Mu Arae b: This Jupiter-class planet has at least 1.67 +/- 0.11 times Jupiter's mass. It moves around Mu Arae at an average distance of only 1.50 +/- 0.02 AUs (a semi-major axis around Mars's orbital distance) in an elliptical orbit (e= 0.31) that takes around 1.79 years (654.5 days) to complete
g Mu Arae c: A gas giant around 3.10 +/- 0.71 Jupiter-masses, the planet has a highly eccentric outer orbit (e~ 0.57 +/- 0.01) with a semi-major axis of 4.17 +/- 0.07AUs, which may take roughly 8.18 years (2986 +/- 30 days) to complete. It has a maximum separation of 0.43 arc-seconds (about 6.6 AUs) from Mu Arae

Habitable zone
g The orbit of an Earth-like planet (with liquid water) around Mu Arae may be centered around 1.3 AU - between the orbital distances of Earth and Mars in the Solar System - with an orbital period around 1.31 years (478 days). However, the eccentric orbit of planet b at an average orbital distance of around 1.5 AU would disrupt the orbit of an Earth-type planet around Mu Arae's water zone.

Orbital map
g See map

View from star
g NA

Nearby stars
(Star systems within 10 ly plus bright stars up to 20 ly)
g CD-51 10924 AB: 3.5 ly
g CP-58 7399: 7.6 ly
g CP-58 7076: 8 ly
g CD-52 7989: 9.7 ly
g CP-60 6718 AB: 9.8 ly
g CP-62 5888 (K7 V): 9.9 ly
g Iota Pavonis AB (G0-3 V-IV ?): 13 ly
g L 489-58 AB (sdG0 /VI ?): 16 ly
g HR 6748 (G3-5 V): 16 ly
g HD 147513 / HR 6094 AB (G3-5 V DA2 /VII): 17 ly
g Beta Trianguli Australis A: 17 ly
g Zeta Trianguli Australis AB (F9-G0 V ?): 19 ly
g Nu2 Lupi (G2-5 V): 19 ly
g HR 7232 (G5-8 V-IV): 20 ly

Map locating star system
g NA

Location in Earth sky
g Lies in the northeastern corner of Constellation Ara, the Altar, southeast of Alpha Arae, south of Lambda Arae, southwest of Theta Arae, and northeast of Beta Arae.

Other names
g Mu Ara, HR 6585, Gl 691, Hip 86796, HD 160691, CD-51 11094, CP(D)-51 10535, SAO 244981, FK5 662, LTT 7053

Sci-fi mentions
g In "Star Trek" universe, in Federation space, roughly between Earth Outpost 3 and Starbase 718 near the Romulan Neutral Zone
g In Chris Berman's novel "Ace of Aces," the fourth planet is much like Earth but without sentient inhabitants

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Dwight Williams said...

Star Trek: Star Charts by Geoffrey Mandel and company, and Keith R.A. deCandido's Trek novel Articles of the Federation both make mention of this system.

Rob Bignell said...

Thanks for the addition, Dwight.