Stellar evolution
Videos
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions o
The violent youth of stars like the Sun
Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right
The change in size with time of a Sun-like star
The Cat's Eye Nebula, a planetary nebula formed by the death of a star with about the same mass as the Sun
Stellar classification
Videos
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffrac
UGC 5797, an emission-line galaxy where massive bright blue stars are formed
Artist's impression of a Y-dwarf
Image of the carbon star R Sculptoris and its striking spiral structure
Sirius A and B (a white dwarf of type DA2) resolved by Hubble