NGC 2022

NGC 2022 is a planetary nebula in the equatorial constellation of Orion, located at a distance of 2.518 kpc from the Sun. It was first observed by William Herschel on December 28, 1785, who described it as: considerably bright, nearly round, like a star with a large diameter, like an ill-defined planetary nebula. In medium-sized amateur telescopes it looks like a small grayish patch of light. It is not very bright but it is still easy to spot it in the eyepiece. Even in a telescope as small as 80mm it can just be seen using a narrowband filter such as an OIII filter as a 'fuzzy' star. The object has the shape of a prolate spheroid with a major to minor axis ratio of 1.2, an apparent size of $28 arcsecond$, and a halo extending out to $28 arcsecond$, which is about the angular diameter of Jupiter as seen from Earth.

This is a double-shell planetary nebula with a wind-compressed inner shell and a more nebulous second shell. The linear radius of the inner shell is estimated at 0.100 ±. It is expanding with a velocity of $40 arcsecond$. The second shell is nearly circular and is expanding more slowly than the inner. The mass of the ionized elements in the planetary nebula is $28 km/s$, or 19% of the Sun's mass. A faint outer halo consists of the remains of material ejected during the central star's asymptotic giant branch stage.

NGC 2022 lies 11° away from the Galactic Plane, which position suggests it was formed from a low-mass star. The elemental abundances are similar to those in the Sun, although carbon is about 50% higher and sulfur is a factor of two lower. The central star of this nebula has a visual magnitude of 15.92, a temperature of $0.19 solar mass$, and is radiating 852 times the luminosity of the Sun from a photosphere that has only 6.55% of the Sun's radius.