These images portray examples of the most commonly detected sources of EUV radiation - Cool Stars with Hot (Active) Coronae, White Dwarf Stars, and Cataclysmic Variable Stars. Active stellar coronae are typical of many stars with late spectral types (F, G, K and M). Despite these stars' cool surface temperatures, they have hot outer atmospheres which emit EUV radiation.
In the image of our own Sun (spectral type G) during a total solar eclipse (top-left), we can see the Sun's corona, or outer atmosphere, which may be strongly affected by magnetic fields. The EUVE spectrometer telescope has allowed astronomers to observe the active and hot coronae of many other stars like our Sun, helping them understand the underlying physical mechanisms responsible for the active coronal regions.
Among the unusual objects that the EUVE satellite has studied are the dense, Earth-sized remnants of red giant stars - hot white dwarfs. A white dwarf star has nearly the mass of the Sun compressed into a volume the size of the Earth. A teaspoon of this very dense white dwarf material would weigh tons on Earth. An artist conception of a white dwarf star, compared to the Earth for scale, is shown on the top-right. Our own Sun is expected to turn into a white dwarf in about 5 billion years. During the white dwarf stage of a star's life, the surface temperature can reach 100,000 degrees Kelvin, making it a bright emitter of EUV radiation.
A model of a cataclysmic variable star is portrayed at the bottom of this image as envisioned by an artist's conception. In such a binary star system, the infall of matter from a star onto a white dwarf companion produces extreme ultraviolet radiation that is detected by the EUVE satellite.