The Tulip Nebula is a glowing cloud of interstellar gas and dust and gets its name from the flower it appears to resemble in photographs. While a pretty sight itself, the Tulip has an interesting neighbor.
It was cataloged by American astronomer Stewart Sharpless in 1959 as Sharpless Sh2-101. The nebula is about 6000 light-years from Earth, and 70 light-years across and glows as a result of powerful young stars ionising cosmic gas and causing it to emit light.
Tulip Nebula (60 min total exposure Oct 13, 2023)
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An interesting feature of the Tulip Nebula is its nearby neighbor (as seen from our vantage point on Earth), the galactic X-ray source known as Cygnus X-1.
Cygnus X-1 is one of the strongest X-ray sources in the sky as seen from Earth and in 1964 was determined to be the site of the first black hole ever discovered. The system consists of a bright blue star HD 226868 (which we can easily see) and a high mass very small invisible object. The pair orbit around each other in under 6 days. Measurements show that the the compact object has a mass of 15 Suns and its diameter is only about 30 miles. That means it is a black hole. The black hole pulls gas off the surface of the star and this gas forms a spiral (accretion disk) as it falls towards the center of the black hole. Friction heats the gas in an accretion disk to incredibly high temperatures, so hot that it emits X-rays. Cygnus X-1 is about 7400 light years away from us, somewhat further than the Tulip Nebula.