Are stars all burning out, or are new ones forming?

Answer 1

Stars are being born as well as dying, said Dr. Nolan Walborn, an astronomer at the Space Telescope Science Institute in Baltimore, but the rate varies greatly from galaxy to galaxy.

One mission of the Hubble Space Telescope is to observe star-formation regions, he said.

Stars form from huge clouds of dust and gas. If a cloud begins to contract because of its own gravity, its interior heats up as gravitational energy is converted to heat energy, reaching millions of degrees, and nuclear reactions begin that change one element into another, releasing energy.

The pressure tends to expand the cloud back out, Dr. Walborn said, but eventually equilibrium is reached. "That is what a star is," he said, "a mass of gas at equilibrium between gravity's inward pressure and outward pressure from nuclear reactions."

A star has a finite lifetime because it is burning fuel. For 90 percent of its life, it burns hydrogen into helium. When the hydrogen is used up, the pressure decreases, but gravity never disappears, so the star contracts until the temperature climbs again, this time reaching hundreds of millions of degrees, while reactions convert helium to carbon and oxygen. The star can then remain stable for a briefer time. Eventually the star dies, when the reactions only consume energy but do not produce it..

Answer 2

Stars are formed within molecular clouds; large regions of high density in the interstellar medium (though still less dense than the inside of an earthly vacuum chamber). These clouds consist mostly of hydrogen, with about 23–28% helium and a few percent heavier elements. One example of such a star-forming nebula is the Orion Nebula.[21] As massive stars are formed from these clouds, they powerfully illuminate and ionize the clouds from which they formed, creating an H II region

An evolved, average-size star will now shed its outer layers as a planetary nebula. If what remains after the outer atmosphere has been shed is less than 1.4 solar masses, it shrinks to a relatively tiny object (about the size of Earth) that is not massive enough for further compression to take place, known as a white dwarf.[35] The electron-degenerate matter inside a white dwarf is no longer a plasma, even though stars are generally referred to as being spheres of plasma. White dwarfs will eventually fade into black dwarfs over a very long stretch of time.


The Crab Nebula, remnants of a supernova that was first observed around 1050 ADIn larger stars, fusion continues until the iron core has grown so large (more than 1.4 solar masses) that it can no longer support its own mass. This core will suddenly collapse as its electrons are driven into its protons, forming neutrons and neutrinos in a burst of inverse beta decay, or electron capture. The shockwave formed by this sudden collapse causes the rest of the star to explode in a supernova. Supernovae are so bright that they may briefly outshine the star's entire home galaxy. When they occur within the Milky Way, supernovae have historically been observed by naked-eye observers as "new stars" where none existed before.[36]

Most of the matter in the star is blown away by the supernovae explosion (forming nebulae such as the Crab Nebula[36]) and what remains will be a neutron star (which sometimes manifests itself as a pulsar or X-ray burster) or, in the case of the largest stars (large enough to leave a stellar remnant greater than roughly 4 solar masses), a black hole.[37] In a neutron star the matter is in a state known as neutron-degenerate matter, with a more exotic form of degenerate matter, QCD matter, possibly present in the core. Within a black hole the matter is in a state that is not currently understood.

The blown-off outer layers of dying stars include heavy elements which may be recycled during new star formation. These heavy elements allow the formation of rocky planets. The outflow from supernovae and the stellar wind of large stars play an important part in shaping the interstellar medium.

Answer 3

They are burning out and new ones forming continually,and will do so until the universe goes out of existence.

Answer 4

Both.
Many more don't even get to become stars, just B-movie actors.

Answer 5

Yes and yes.