Minkowski 2-9, abbreviated M2-9, and also known as Minkowski’s Butterfly or just Butterfly Nebula, was discovered by Rudolph Minkowski in 1947. It has an apparent visual magnitude of 14.7 and is located about 2,100 light-years away from Earth in the direction of the constellation Ophiuchus, the Serpent Bearer.
M2-9 represents the spectacular “last gasp” of a binary star system at the nebula’s center. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance. The central stars are known to be a very close pair which orbit one another at perilously close distances. It is even possible that one star is being engulfed by the other. The gravity of one pulls off weakly bound gas from the surface of the other, and flings it into a thin, dense disk which surrounds both stars and extends well into space, measuring approximately 10 times the diameter of Pluto’s orbit.
Because of the nebula’s shape and the measured velocity of the gas, in excess of 200 miles per second (approx. 322 kilometres per second), astronomers believe that the description as a supersonic jet exhaust is quite apt. Ground-based studies have shown that the nebula’s size increases with time, suggesting that the stellar outburst that formed the lobes occurred just 1,200 years ago. In this image, neutral oxygen is shown in red, once-ionized nitrogen in green, and twice-ionized oxygen in blue.
Credits: Astro Washington Edu., Hubble, NASA, SOFIA, Wikipedia.