NGC 2346
Encyclopedia
NGC 2346 is a planetary nebula
near the celestial equator
in the Monoceros constellation. It is bright and conspicuous and has been extensively studied. Among its most remarkable characteristics is its unusually cool central star, which is a spectroscopic binary, and its unusual shape.
The binary star
, which has a period of about 16 days, is also variable
, probably due to dust in orbit around it. The dust itself is heated by the central star and so NGC 2346 is unusually bright in the infrared part of the spectrum. When one of the two stars evolved into a red giant
, it engulfed its companion, which stripped away a ring of material from the larger star’s atmosphere. When the red giant’s core was exposed, a fast stellar wind
inflated two ‘bubbles’ from either side of the ring.
Planetary nebula
A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
near the celestial equator
Celestial equator
The celestial equator is a great circle on the imaginary celestial sphere, in the same plane as the Earth's equator. In other words, it is a projection of the terrestrial equator out into space...
in the Monoceros constellation. It is bright and conspicuous and has been extensively studied. Among its most remarkable characteristics is its unusually cool central star, which is a spectroscopic binary, and its unusual shape.
The binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
, which has a period of about 16 days, is also variable
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
, probably due to dust in orbit around it. The dust itself is heated by the central star and so NGC 2346 is unusually bright in the infrared part of the spectrum. When one of the two stars evolved into a red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
, it engulfed its companion, which stripped away a ring of material from the larger star’s atmosphere. When the red giant’s core was exposed, a fast stellar wind
Stellar wind
A stellar wind is a flow of neutral or charged gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric.Different types of stars have...
inflated two ‘bubbles’ from either side of the ring.