Orbital
Distance

(a=AUs)
Orbital
Period

(P=years)
Orbital
Eccentricity

(e)
Orbital
Inclination

(i=degrees)
Mass
Estimate

(Solar)

Diameter

(Solar)

Density

(Earths)
Surface
Gravity

(Earths)

Metallicity
(Solar)
Aab-BC Mass Center0.0........................
Aab Mass Center100?>3,600??247...............
Mu Herculis Aa2.9650.3268~11.44......1.3-3
Disrupted H.Z. Aa?1.62.0068...............
Mu Herculis Ab14.3650.32680.2............
BC Mass Center200?>3,600?66.2247...............
Mu Herculis B5.743.20.17866.20.310.48.........
H.Z. B0.0670.022066.2...............
Mu Herculis C5.743.20.17866.20.310.4.........
H.Z. C0.0540.0230?...............


NOTE: This animation attempts to relate the complicated orbits (and possible habitable zones) of star groups Aab and BC in the Mu Herculis system to their respective centers of mass. To enlarge the display, the orbits have been arbitrarily rotated by 135 degrees. Aljthough actual inclinations of the Aab and BC orbital system and of their component orbits (from the perspective of an observer on Earth) are displayed, the orbital inclination of any planet that may be discovered someday in this star system would likely be different from those of the habitable zone orbits depicted here. (For the purposes of this animation, the masses of stars or brown dwarfs Aa, Ab, B, BC, and Bc are assumed to be 1.0, 0.2, 0.31, and 0.31 Solar, respectively.)

Mu Herculis A (or Aa) appears to have an unseen, close companion (Mu Herculis D or Ab) with as much as a fifth of Sol's mass. In turn, this close binary pair (Aab) has another companion binary of stars (BC). According to the Astronomisches Rechen-Institut's Catalogue of Nearby Stars (ARICNS) notes on Star B, the BC companion binary pair has an observed separation of about 286 AUs (34.0" at a HIPPARCOS parallax of 0.11905+/-0.00062") from primary pair Aab at an orbital inclination of 247 (1955) from the perspective of an observer on Earth. (For the purposes of this animation, the star pairs Aab and BC are assumed to move in a circular orbit with a semi-major axis of 286 AUs.)

Astrometric analysis suggests that Star D is in an elliptical orbit (e= 0.34) around Star Aa and has roughly a fifth of Sol's mass (Wulff D. Heintz, 1994, pages 2341 and 2346; and Heintz, 1987, page 1080 -- which Heintz referred to as Stars A and Aa versus the more typical designations Aa and Ab). According to the Astronomisches Rechen-Institut's Catalogue of Nearby Stars (ARICNS), Heintz's 1994 analysis of Mu Herculis Aa also derived an updated period of 65 years which would imply a semi-major axis of just under 17.2 AUs, assuming that the combined mass of Mu Herculis Aab is 1.2 times that of Sol's (which is consistent with Wanner's 1967 estimate of the mass ratio of 0.50 (+/- 0.04) for the binary pair BC -- combined -- to the primary).

Star B and its stellar companion C are separated by an "average" semi-major axis) of 11.4 AUs. They have an elliptical orbit (e= 0.18) that swings them between 9.4 and 13.5 AUs apart in an orbit that lasts about 43.2 years (Paul Couteau, 1960).


 

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