Orbital
Distance

(a=AUs)
Orbital
Period

(P=years)
Orbital
Eccentricity

(e)
Orbital
Inclination

(i=degrees)

Mass

(Solar)

Diameter

(Solar)

Density

(Earths)
Surface
Gravity

(Earths)

Metallicity
(Solar)
AB Mass Center0.0........................
Achird A27.24800.49734.760.910.98......0.63-0.68
Inner H.Z. Edge A?0.900.81034.76...............
Outer H.Z. Edge A?1.802.29034.76...............
Achird B44.24800.49734.760.560.65......0.63-0.68
Inner H.Z. Edge B?0.590.59034.76...............
Outer H.Z. Edge B?1.181.65034.76...............


NOTE: This animation attempts to relate the orbits (and possible habitable zones) of Stars A and B in the Eta Cassiopeiae AB system -- also known as Achird -- to their common center of mass. To enlarge the display, the orbits have been arbitrarily rotated by 45 degrees. Although the initial display shows the system's actual orbital tilt (at an inclination of 34.76) from the visual perspective of an observer on Earth, the orbital inclination of any planet that may be discovered someday around either star would likely be different from those of the habitable zone orbits depicted here.

According to a 1969 article by Kaj Aage Gunnar Strand (1907-2000; obit), Stars A and B are separated by an "average" distance of 71 times the Earth-Sun distance (AU) (of a semi-major axis) in an eccentric orbit (e= 0.497) of about 480 years, so that the two stars get as close as 36 AU and as far away as 107 AU. However, Achird is no longer thought to have a spectroscopic binary with a nine-day orbital period (Morbey and Griffin, 1987; and Helmut Abt, 1987).


 

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