Sharpless 101 (Sh2-101) is an emission nebula (H II region) in the constellation Cygnus. It is also called the Tulip Nebula because in photographs it resembles the outline of a tulip. The nebula was cataloged in 1959 by astronomer Stewart Sharpless. It lies at a distance of about 7,000 light-years from Earth.

In the same region of the sky, very close to Sh2-101 as seen from Earth, lies the microquasar Cygnus X-1, one of the first identified black hole candidates. Cygnus X-1 is located about 15′ west of the nebula. Its companion star is an O9.7 Iab supergiant with 21 solar masses and 20 times the Sun’s radius. The binary system has an orbital period of 5.8 days, with a separation of about 0.2 AU. The black hole itself has a mass of 15 solar masses and a Schwarzschild radius of 45 km. A bow shock is produced by energetic particle jets from the black hole as they interact with the interstellar medium.