What is a Nova?
My daughter is doing a project on nova. Of all the internet information I cannot specificly find this topic. Could you please forward any info on this matter to me it would be greatly appreciated. Thank you. A nova is a strong, rapid increase in the brightness of a star. The word comes from the latin for “new star,” because often a star previously too dim to be seen with the naked eye can become the brightest object in the sky (besides the sun and the moon) when it becomes a nova. Novae are now known to be caused by a star briefly re-igniting after having lain dormant for many years. Stars shine due to the nuclear fusion reactions in their cores, which process hydrogen into helium, releasing energy in the process. When the hydrogen is used up, sun-like stars slough off their outer envelopes, and become very small, very hot “white dwarfs.” These white dwarfs are the inert cores of dead stars which have used up all of their available fuel. Now, stars often come in pairs, or “binaries,” w
A nova is a nuclear-powered eruption on the surface of a white dwarf. A white dwarf is a burned-out cinder of what once was a star like the Sun. The gravity of a white dwarf is so strong the white dwarf becomes essentially solid, or in other words, becomes degenerate. (Painting by Pat Rawlings, NASA/STScI) Gas from a close companion star spills onto the white dwarf. Star systems like this are called cataclysmic variables. (Painting by Pat Rawlings, NASA/STScI) The temperature, pressure, and degeneracy build up until the gas detonates, in a thermonuclear runaway. (Painting by Pat Rawlings, NASA/STScI) The atmosphere of the white dwarf leaps up, expanding in a fireball, which engulfs the white dwarfs companion star. (Hubble Space Telescope images by F. Paresce.) The fireball expands and cools. When it becomes large enough to be resolved (seen separate from the stars), its called a nova shell. In other words, a nova shell is the resolved nebular remnant of the nova: nebula is cloud in Lat
The word nova means “new star.” Ancient civilizations interpreted these events as the creation of a new star. Novae (plural of nova) are actually explosions that occur on stars near the end of their lives. In a binary system, a system in which two stars closely orbit each other, one star may influence the other. If the binary system consists of a white dwarf and a main-sequence star, gas may be pulled from the main-sequence star to the white dwarf. This is like dumping lighter fluid onto hot coals; the surface of the white dwarf explodes. Depending on how energetic the explosion is, the novae will fade away in a few days to a few weeks. In the images below, you can see a nova appearing and fading.
A nova is a type of stellar explosion smaller than a supernova or hypernova. The phenomenon occurs in binary star systems, where a white dwarf star absorbs a critical amount of matter from its companion, compressing hydrogen onto its surface and eventually igniting a nuclear explosion. Only about 1/10,000 solar masses of material is ejected, in comparison to 1.38 solar masses of material in a Type I supernova and a dozen or more solar masses in a Type II supernova. Although a Type I supernova also involves a white dwarf star, in that case a majority of the star’s entire mass is fused. In the case of a nova, only a tiny percentage is. A white dwarf star is made up of degenerate matter, a super-dense phase of matter with the unusual property that its pressure is only weakly related to temperature. When a white dwarf’s gravitational field sucks hydrogen gas from a nearby star, the gas fuses to the surface of the dwarf, joining the degenerate matter. A white dwarf packs a mass similar to t
A nova is a sudden brightening of a star. Novae are thought to occur on the surface of a white dwarf star in a binary system with another star. If these two stars are close enough to each other, material from one star can be pulled off its surface and onto the white dwarf. Occasionally, the temperature of this new material on the surface of the white dwarf may become hot enough to start nuclear fusion and suddenly the surface of the white dwarf will start to fuse the hydrogen into helium over its surface. This causes the white dwarf to suddenly become very bright. Ancient astronomers, who did not have telescopes and other instruments modern astronomers now have, did not realize that there was a star already there, and so they would just see a new star where they had not seen one before. “Stella Nova” means “new star” in Latin and this is where novae got their name. Supernovae were once thought to just be really bright novae (hence the addition of “super” to their name). If you look at
