M51-ULS-1 is a high-mass X-ray binary system in the Whirlpool Galaxy consisting of two components, a
blue supergiant, and a
compact object. The binary system has a predicted age between 4 and 16 million years old; it was also found that the system is probably no older than 100 million years old. The primary star has a spectral type of B2-8la discovered using
Hubble Space Telescope photometry. The primary star has a mass of about 20 solar mass|. Because of the star's mass it is predicted that the primary star might undergo a
hydrogen-poor
supernovae in the future. The primary star has an estimated size of \sqrt{\biggl(\frac{5,772}{26,068}\biggr)^4 \cdot {260,010}} = 25\ R_\odot.}} The secondary object, M51-ULS-1 B, is a stellar remnant and is either a
black hole or
neutron star. If the secondary object is a black hole, it would have a mass of 10 ; classifying the secondary object as a
stellar-mass black hole. If it is a black hole, using its mass it would have a
Schwarzschild radius of roughly 30
kilometers. If the secondary object is a neutron star, it would have mass of 1.4 . It is known that the secondary object is
accreting 10−6 worth of material every year from the primary star. == Planetary system ==