Stellar evolution Stellar evolution A Black Dwarf constitutes the remains of a Sun-sized star which has evolved to a white dwarf and subsequently cooled down such that it no longer emits visible light. None are known to exist in our universe, as the time taken for a white dwarf to cool to such a degree is hypothesized to be longer than the lifespan of the universe to date. ...more on Wikipedia about "Black dwarf"
Herbig-Haro objects are small patches of nebulosity associated with newly-born stars, and are formed when gas ejected by young stars collides with clouds of gas and dust nearby at speeds of several hundred kilometres per second. Herbig-Haro objects are ubiquitous in star-forming regions, and several are often seen around a single star, aligned along its rotational axis. ...more on Wikipedia about "Herbig-Haro object"
The Hertzsprung-Russell diagram (usually referred to by the abbreviation H-R diagram or HRD, also known as a Colour-Magnitude (CM) diagram) shows the relationship between absolute magnitude, luminosity, classification, and surface temperature of stars. The diagram was created circa 1910 by Ejnar Hertzsprung and Henry Norris Russell. ...more on Wikipedia about "Hertzsprung-Russell diagram"
The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. Stars located on this band are known as main-sequence stars or dwarf stars. The coolest dwarfs are the red dwarfs. ...more on Wikipedia about "Main sequence"
A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. They are in fact unrelated to planets; the name originates from a supposed similarity in appearance to giant planets. They are a short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years. About 1,500 are known to exist in our galaxy. ...more on Wikipedia about "Planetary nebula"
Protostar is a period after clouds of hydrogen, helium and dust begin to contract and before the a star reaches the main sequence. ...more on Wikipedia about "Protostar"
The Red Clump is a region on the Hertzsprung-Russell diagram occupied primarily by metal-rich red giant stars. It is above/right relative to the main sequence and so consequently stars here are brighter than main sequence stars of the same surface temperature (or colder than stars of comparable luminosity). ...more on Wikipedia about "Red clump"
Star formation is the process by which gas in molecular clouds change into the ball of plasma we call a star. ...more on Wikipedia about "Star formation"
In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat. Over the course of that time, the star will change radically. ...more on Wikipedia about "Stellar evolution"
Supernovae refer to several types of stellar explosions that produce extremely bright objects made of plasma that decline to invisibility over weeks or months. ...more on Wikipedia about "Supernova"
A white dwarf is an astronomical object which is produced when a low or medium mass star dies. These stars are not heavy enough to generate the core temperatures required to fuse carbon in nucleosynthesis reactions, and after they have become a red giant during their helium-burning phase, they will shed their outer layers to form a planetary nebula, leaving behind an inert core consisting mostly of carbon and oxygen. ...more on Wikipedia about "White dwarf"
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