is a nearest star system about 27.4 light years
from Earth in the constellation Hercules
. Its main star, Mu Herculis A (possibly a binary) is fairly similar to the Sun
although more highly evolved
. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant.
Mu Herculis A and the binary itself pair B-C are separated by 286 AUs. On the other hand stars B-C are separated by 11.4 AUs. Their orbit is quite elliptic (e=0.18) and both stars swing each other between 9.4 and 13.5 AUs.
Mu Herculis Ab (or D)?
Star A is itself suspected to be a close binary with a low mass stellar or a large substellar companion, probably at 17.2 AUs in elliptic orbit (e=0.34). Nevertheless the existence of such an object has still not confirmed