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NGC 7027 has a rich and highly ionized spectrum caused by its hot central star. [7] The progenitor star of NGC 7027 is believed to have been about 3 to 4 times the mass of the Sun before the nebula was formed. [7] It is possible that the central white dwarf of NGC 7027 has an accretion disk that acts as a source of high temperatures. [24]
The denser and more massive region, located in a central position, may have originated from a generalized collapse phenomenon; hot star formation took place in this area, which thus illuminated the surrounding gases, transforming the molecular cloud into the compact H II region that can be observed today. DR 21 is an extremely young structure ...
All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula at the end of its life cycle. [8] They are relatively short-lived phenomena, lasting perhaps a few tens of millennia, compared to considerably longer phases of stellar evolution. [9]
N44 is classified as an emission nebula because it contains large regions of ionized hydrogen. However, the three strongest emission lines in the nebula are singly ionized oxygen atoms, which emit at an ultraviolet wavelength of 372.7 nm , doubly-ionized oxygen atoms, which emit at a blue-green wavelength of 500.7 nm, and neutral hydrogen atoms ...
Still other nebulae form as planetary nebulae. This is the final stage of a low-mass star's life, like Earth's Sun. Stars with a mass up to 8–10 solar masses evolve into red giants and slowly lose their outer layers during pulsations in their atmospheres.
IC 11, Sh2-184, [3] Sharpless 184, [1] LBN 616, LBN 123.17-06.28, Pacman Nebula See also: Lists of nebulae NGC 281 , IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way 's Perseus Spiral Arm .
The Sun is the star at the center of the Solar System.It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies.
NGC 3132 (also known as the Eight-Burst Nebula, [2] the Southern Ring Nebula, [2] or Caldwell 74) is a bright and extensively studied planetary nebula in the constellation Vela. Its distance from Earth is estimated at 613 pc or 2,000 light-years .