When a white dwarf or neutron star is a member of a close binary star system, its companion star can transfer mass to it. Material falling gradually onto a white dwarf can explode in a sudden burst of fusion and make a nova.

What mechanism produces a nova? A) After the core of a supermassive star has begun to change to iron, nuclear fusion ceases. This causes the entire star to collapse and releases tremendous amounts of energy. B)Novae are produced by pieces of space debris heating up and glowing as they fall through Earth’s atmosphere.

A nova is an explosion from the surface of a white-dwarf star in a binary star system. A nova occurs when the white dwarf, which is the dense core of a once-normal star, “steals” gas from its nearby companion star.

What is a nova and what causes it? It is a sudden flare up in a star system. This occurs when a white dwarf is part of a binary system. The less massive star reaches the red giant stage, reaches its inner Roche limit, and begins to transfer mass to the WD, forming an accretion disk around it.

How can one typically adjust the magnification of any telescope? Swap out the eyepiece for one of a different focal length.

0.08 solar masses

A white dwarf star is in balance between gravity and degeneracy pressure, but if the mass is too large (greater than 1.4 solar masses, called the Chandrasekhar limit), the degeneracy pressure is not adequate to hold up the star, and the star collapses. The white dwarf then collapses.

What would happen if mass is added to a 1.4 solar mass white dwarf? The star would eventually become a black hole. The star would erupt as a type I supernova. The core would collapse as a type II supernova.

The upper mass-limit for a main sequence star that will go on to form a white dwarf rather than a neutron star is not precisely known but is thought to be about 8 solar masses. A 2 solar-mass star will probably end up as a 0.7 solar-mass white dwarf.

1 : a star of spectral type A or F having a moderate surface temperature and a white or yellowish color. 2a : an annual morning glory (Ipomoea lacunosa) of the southern U.S. with star-shaped leaves and small white or purplish flowers.

A typical white dwarf has a carbon and oxygen mass similar to the Sun, but is much smaller in size (similar to the Earth). It is much hotter (25,000 K), but because of its small size its luminosity is low.

A white dwarf has a higher surface temperature than a red giant star.

Usually, white dwarfs are composed of carbon and oxygen (CO white dwarf). Stars of very low mass will not be able to fuse helium, hence, a helium white dwarf may form by mass loss in binary systems. The material in a white dwarf no longer undergoes fusion reactions, so the star has no source of energy.

The only reason there are “bright” red stars is that their radius is incredibly large. White dwarfs on the other hand are not stars in the sense that they do not fuse anything, they simply glow due to the lingering heat that was generated during their time as stars.

A red giant becomes a white dwarf when it runs out of fusable material.

At other times, the white dwarf may pull just enough material from its companion to briefly ignite in a nova, a far smaller explosion. Because the white dwarf remains intact, it can repeat the process several times when it reaches that critical point, breathing life back into the dying star over and over again.