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The most common observable evidence of a remnant planetary system is pollution of the spectrum of a white dwarf with metal absorption lines. 27–50% of white dwarfs show a spectrum polluted with metals, [153] but these heavy elements settle out in the atmosphere of white dwarfs colder than 20 000 K.
White dwarfs with a spectrum that indicates high levels of metal contamination of the photosphere often have a circumstellar disk. In the case of van Maanen 2, observations at a wavelength of 24 μm do not show the infrared excess that might be generated by a dusty disk. Instead there is a noticeable deficit.
The white dwarf has a mass of 0.6 M ☉, radius of 0.012 R ☉ (1.34 R 🜨) and a temperature of 15,020 K, typical for white dwarf stars. It has been a white dwarf for 224 million years. [6] [10] The star's spectrum includes strong absorption lines due to magnesium, aluminium, silicon, calcium, iron and nickel.
This includes both red dwarfs and brown dwarfs that are very faint in the visible spectrum. [95] Brown dwarfs, ... is the modern classification used for white dwarfs ...
At a distance of about 25 parsecs (80 ly) from Earth, it is the outer component of a visual triple star system consisting of an inner pair of red dwarf stars, named G 229-20. The white dwarf displays a featureless absorption spectrum, lacking strong optical absorption or emission features in its atmosphere.
A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmospheres and the spectral type DA; [1] DBV, or V777 Her, stars, with helium-dominated atmospheres and the spectral type DB; [2] and GW Vir stars, with atmospheres dominated ...
A slowly cooling stellar ember called a white dwarf with a scar on its face is providing new insight into the behavior of certain "cannibal" stars at the end of their life cycle. Using the ...
GD 356 is a white dwarf in the constellation of Draco showing an unusual emission of circular polarised light. The star is 65 light years from earth. [4] The class of this white dwarf is DA e meaning that it has a cool helium rich atmosphere. [5]