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Once a star has converted all the hydrogen in its core into helium, the core is no longer able to support itself and begins to collapse. It heats up and becomes hot enough for hydrogen in a shell outside the core to start fusion. The core continues to collapse and the outer layers of the star expand. At this stage, the star is a subgiant. Very ...
Matter is made up by atoms (formed by protons and other subatomic particles). When the environment is right, atoms can join together and form molecules, which give rise to most materials studied in materials science. But certain environments, such as high temperatures, don't allow atoms to form molecules, as the environmental energy exceeds ...
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 ...
The nebula's color depends on its chemical composition and degree of ionization. Due to the prevalence of hydrogen in interstellar gas, and its relatively low energy of ionization, many emission nebulae appear red due to strong emissions of the Balmer series. If more energy is available, other elements will be ionized, and green and blue ...
A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H 2), and the formation of H II regions.
The Boomerang Nebula is a protoplanetary nebula [2] located 5,000 light-years from Earth in the constellation Centaurus. It is also known as the Bow Tie Nebula and catalogued as LEDA 3074547. [ 3 ] The nebula's temperature is measured at 1 K (−272.15 °C ; −457.87 °F ) making it the coolest natural place currently known in the Universe .
Particularly massive iron cores may collapse the entire star into a black hole with no visible explosion, or a sub-luminous supernova as radioactive 56 Ni falls back onto the black hole. [ 39 ] A type Ic supernova can produce a GRB if the star is rotating and has an appropriate mass.
The strong, dense stellar winds from Wolf-Rayet stars consist of streams of charged particles traveling at speeds of thousands of kilometers per second. These winds slam into the surrounding interstellar medium, generating shock waves that heat and ionize the gas and dust, causing it to glow and emit radiation in visible and other wavelengths.