![]() Type I supernovae lack a hydrogen signature in their light spectra and are generally thought to originate from white dwarf stars in a close binary star system (opens in new tab). (Image credit: NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.) (opens in new tab) Type I supernovae This Chandra X-ray photograph shows Cassiopeia A (Cas A, for short), the youngest supernova remnant in the Milky Way. Instead they collapse to form black holes (opens in new tab). Stars much more massive than the sun (around 20 to 30 solar masses) might not explode as a supernova, astronomers think. Both types have the signature of hydrogen in their spectra. The light of Type II-L supernovae declines steadily after the explosion, while the light of Type II-P supernovae stays steady for a longer period before diminishing. Type II supernova sub-categories are classified based on their light curves, which describes how the intensity of the light changes over time. What's left is an ultra-dense object called a neutron star, a city-sized object that packs the mass of the sun in a small space. Related: Star-smash supernova? New type of stellar explosion possibly seen (opens in new tab)Įventually the implosion bounces back off the core, expelling the stellar material into space, forming the supernova. For this reason, these Type-II supernovae are also known as core-collapse supernovae. Once the star's core surpasses a certain mass (called the Chandrasekhar limit), it begins to implode. Next, gradually heavier elements build up at the center, and the star forms onion-like layers of material, with elements becoming lighter toward the outside of the star. However, it will have enough mass and pressure to fuse carbon. Like the sun, it will eventually run out of hydrogen and then helium fuel at its core. For a star to explode as a Type II supernova, it must be several times more massive than the sun (estimates run from eight to 15 solar masses (opens in new tab)). Let's look at the more exciting Type II first. (Image credit: NASA/ESA and Jeff Hester (Arizona State University).) (opens in new tab) Type II supernovae The Hubble Space Telescope has caught the most detailed view of the Crab Nebula in one of the largest images ever assembled by the space-based observatory. Type II supernova: star runs out of nuclear fuel and collapses under its own gravity. Type I supernova: star accumulates matter from a nearby neighbor until a runaway nuclear reaction ignites. (Though the news for Earth still isn't good, because once the sun runs out of its nuclear fuel, perhaps in a couple billion years, it will swell into a red giant (opens in new tab) that will likely vaporize our world, before gradually cooling into a white dwarf (opens in new tab).) But with the right amount of mass, a star can burn out in a fiery explosion.Ī star can go supernova in one of two ways: Our sun, for example, doesn't have enough mass to explode as a supernova. Related: Giant, galactic bubble is driving star formation, new study finds (opens in new tab)Įxactly how a star dies depends in part on its mass. ![]() ![]() Department of Energy (opens in new tab).Ībout 10 million years ago, a cluster of supernovae created the "Local Bubble," a 300-light-year long, peanut-shaped bubble of gas in the interstellar medium that surrounds our solar system. This means a star explodes every 10 seconds or so somewhere in the universe, according to the U.S. On average, a supernova will occur once every 50 years in a galaxy the size of the Milky Way (opens in new tab), according to research by the European Space Agency (opens in new tab). The scientists suggested that supernovas happen when ordinary stars collapse into neutron stars. The term "supernova" was first used by Walter Baade and Fritz Zwicky at Mount Wilson Observatory (opens in new tab), who used it in relation to an explosive event they observed, called S Andromedae (also known as SN 1885A), located in the Andromeda Galaxy (opens in new tab).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |