The theoretical dividing line between a black hole and a neutron star is about 3 solar masses, so all of the systems thought to contain black holes had compact objects above that limit.

• 理论上区分黑洞和中子星的标准是大约3倍太阳质量，所以被认为是黑洞的宇宙系统都应该是具有三个太阳以上的质量的大密度物体。