# A nearby binary star system with four planets

Pairs or multiple systems of stars which orbit their common center of mass. If we can measure and understand their orbital motion, we can estimate the stellar masses.

Relatively nearby, that is…

‘Upsilon Andromedae is located fairly close to the Solar System… (44 light years). Upsilon Andromedae A has an apparent magnitude of +4.09, making it visible to the naked eye even under moderately light-polluted skies, about 10 degrees east of the Andromeda Galaxy.’ – Wikipedia

The larger of the binary stars is ups_And A, which has 4 planets orbiting it: b,c,d and e.

The information on this star system was recently updated, so let’s have a look.

Orbital data:
835 b = 3855.287 days
16 c = 3854.992
3 d = 3844.317
1 e = 3848.86
(Data: exoplanet.eu)

Synodic data:
819 b-c = 3855.293 days
13 c-d = 3857.464
2 d-e = 3842.05

b,c,d group notes:
13, 819, and 832 are all divisible by 13
Result: 1 c-d = 63 b-c = 64 b-d (1+63 = 64)
In Fibonacci terms: 1 c-d = 21*3 b-c = 8*8 b-d

c,d,e group notes:
2 and 13 are prime, 15 c-e = 5*3 (2+13 = 15)
In Fibonacci terms: 2 d-e = 13 c-d = 5*3 c-e

So the recurring synodics of both groups can be expressed with these Fibonacci numbers:
1,2,3,5,8,13,21

Other notes:
The 3:1 ratio of the orbits of d and e is unusual, possibly related to the binary star set-up?

A paper was written about the ‘apsidal alignment’ of c and d, also considered unusual. These two monster planets are from 10 to 14 times the size of Jupiter. (The other two are 1.06 and 1.70 times J). These sizes are all best estimates.

via Tallbloke’s Talkshop

https://ift.tt/2z6Siw0

August 19, 2019 at 12:18PM