What color is a white dwarf?
The visible radiation emitted by white dwarfs varies over a wide color range, from the blue-white color of an O-type main sequence star to the red of an M-type red dwarf. White dwarf effective surface temperatures extend from over 150,000 K to barely under 4,000 K.
What is the spectral class of a white dwarf?
A note on the spectral atlas and spectral classification
| Luminosity Class | Description | Comments |
|---|---|---|
| IV | Sub-Giants | |
| V | Dwarfs | Main Sequence |
| sd | Sub-Dwarfs | |
| D | White Dwarfs |
How do we identify white dwarfs?
A low or medium mass star (with mass less than about 8 times the mass of our Sun) will become a white dwarf. A typical white dwarf is about as massive as the Sun, yet only slightly bigger than the Earth. This makes white dwarfs one of the densest forms of matter, surpassed only by neutron stars and black holes.
What light do white dwarfs emit?
Is it continued fusion of elements? White dwarfs emit light because they are very, very hot. No more fusion happens; that’s why it’s a dead star in the first place, and not a live star. But the remains emit black body radiation, like everything that is above absolute zero.
What do white dwarfs do?
White dwarfs are stars that have burned up all of the hydrogen they once used as nuclear fuel. Fusion in a star’s core produces heat and outward pressure, but this pressure is kept in balance by the inward push of gravity generated by a star’s mass.
Why do white dwarfs last so long?
The more surface area it has the more energy it can dissipate in a given time for a given temperature. Furthermore, as a white dwarf cools its surface temperature decreases which further slows the rate of cooling. This means that white dwarfs will stay warm for many billions of years.