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The formation and evolution of the Solar System is a fascinating topic that explores how our planetary system originated from a giant cloud of gas and dust, and how it has changed over billions of years. Learn about the theories and evidence that explain the origin of the Sun, the planets, the asteroids, the comets, and the other celestial bodies that orbit the Sun. Discover how the Solar ...
Dwarf star. A dwarf star is a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. The meaning of the word "dwarf" was later extended to some star-sized objects that are not stars, and compact stellar remnants that are no longer stars.
As the first stars, dwarf galaxies and quasars gradually form, the intense radiation they emit reionizes much of the surrounding universe; splitting the neutral hydrogen atoms back into a plasma of free electrons and protons for the first time since recombination and decoupling. Reionization is evidenced from observations of quasars.
Binary star. The well-known binary star Sirius, seen here in a Hubble photograph from 2005, with Sirius A in the center, and white dwarf, Sirius B, to the left bottom from it. A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen ...
Image of Sirius A and Sirius B taken by the Hubble Space Telescope. Sirius B, which is a white dwarf, can be seen as a faint point of light to the lower left of the much brighter Sirius A. A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun 's ...
Quark star. A quark star is a hypothetical type of compact, exotic star, where extremely high core temperature and pressure have forced nuclear particles to form quark matter, a continuous state of matter consisting of free quarks .
• Notes = Common name(s) or alternate name(s); comments; notable properties [for example: multiple star status, range of variability if it is a variable star, exoplanets, etc.] See also [ edit ] List of stars by constellation
e. The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to ...