What are white dwarfs?
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.
What are the characteristics of white dwarfs quizlet?
White dwarf, in astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation). Typically, a white dwarf star has the mass of the sun and the radius of the earth but does not emit enough light or other radiation to be easily detected.
What is a white dwarf and how does it form?
A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains.
What is a white dwarf composed of quizlet?
White dwarfs are composed of mostly carbon, oxygen, and electrons, whereas neutron stars are composed of mostly neutrons.
Is a white dwarf solid?
Observations have revealed that dead remnants of stars like our Sun, called white dwarfs, have a core of solid oxygen and carbon due to a phase transition during their lifecycle similar to water turning into ice but at much higher temperatures. White dwarf stars are some of the oldest stellar objects in the universe.
Why are white dwarfs white?
White dwarf stars, so called because of the white colour of the first few that were discovered, are characterized by a low luminosity, a mass on the order of that of the Sun, and a radius comparable to that of Earth. This limiting mass, known as the Chandrasekhar limit, is on the order of 1.4 solar masses.
Which of the following describes a white dwarf?
A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: Its mass is comparable to that of the Sun, while its volume is comparable to that of Earth. The unusual faintness of white dwarfs was first recognized in 1910.
How does a white dwarf differ from a neutron star quizlet?
A white dwarf is an electron degenerate object, while a neutron star is a neutron degenerate object. A white dwarf has a larger radius and is much less dense than a neutron star. All white dwarfs are less than 1.4 MSun while neutron stars are between 1.4 and 3 MSun.
What is a white dwarf composed of?
The central region of a typical white dwarf star is composed of a mixture of carbon and oxygen. Surrounding this core is a thin envelope of helium and, in most cases, an even thinner layer of hydrogen. A very few white dwarf stars are surrounded by a thin carbon envelope.
What is the event horizon quizlet?
The event horizon is an imaginary spherical outer boundary of a black hole. Once matter crosses this threshold, the speed required for it to escape the black hole’s gravitational grip is greater than the speed of light. This is called gravity.
What color are white dwarfs?
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.
Is white dwarf a variable star?
A white dwarf’s faint luminosity comes from the emission of residual thermal energy; no fusion takes place in a white dwarf. The nearest known white dwarf is Sirius B, at 8.6 light years, the smaller component of the Sirius binary star….Atmosphere and spectra.
| Primary and secondary features | |
|---|---|
| V | Variable |