The table below lists the known reasons for core collapse in massive stars, the types of stars in which they occur, their associated supernova type, and the remnant produced. The metallicity is the proportion of elements other than hydrogen or helium, as compared to the Sun. The initial mass is the mass of the star prior to the supernova event, given in multiples of the Sun's mass, although the mass at the time of the supernova may be much lower. [100] The sight of a supernova explosion might be awful and mesmerizing at the same time, as the beauty of destruction is not alwayseuphoric, yet these humbling events are the celestial distributors of seeds, the explosive pillars of creation. The model for the formation of this category of supernova is a close binary star system. The larger of the two stars is the first to evolve off the main sequence, and it expands to form a red giant. The two stars now share a common envelope, causing their mutual orbit to shrink. The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion. At this point, it becomes a white dwarf star, composed primarily of carbon and oxygen. [84] Eventually, the secondary star also evolves off the main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass. The exact details of initiation and of the heavy elements produced in the catastrophic event remain unclear. [85] When 1987A blew up, neutrino science was in its infancy—even so, two dozen neutrinos were recorded by three detectors working at the time. If a supernova explodes within our galaxy now, the global network of detectors will record hundreds or even thousands of neutrinos.

Scientists have described two distinct types of supernovas. In a Type I supernova, a white dwarf star pulls material off a companion star until a runaway nuclear reaction ignites; the white dwarf is blown apart, sending debris hurtling through space. Kepler’s was a Type I. In a Type II supernova, sometimes called a core-collapse supernova, a star exhausts its nuclear fuel supply and collapses under its own gravity; the collapse then “bounces,” triggering an explosion. Type IIn supernovae are characterised by additional narrow spectral lines produced in a dense shell of circumstellar material. Their light curves are generally very broad and extended, occasionally also extremely luminous and referred to as a superluminous supernova. These light curves are produced by the highly efficient conversion of kinetic energy of the ejecta into electromagnetic radiation by interaction with the dense shell of material. This only occurs when the material is sufficiently dense and compact, indicating that it has been produced by the progenitor star itself only shortly before the supernova occurs. [155] [156]

Calcium-rich supernovae are a rare type of very fast supernova with unusually strong calcium lines in their spectra. [65] [66] Models suggest they occur when material is accreted from a helium-rich companion rather than a hydrogen-rich star. Because of helium lines in their spectra, they can resemble type Ib supernovae, but are thought to have very different progenitors. [67] Type II [ edit ] Light curves are used to classify type II-P and type II-L supernovae. [61] [68]

Compared to a star's entire history, the visual appearance of a supernova is very brief, sometimes spanning several months, so that the chances of observing one with the naked eye is roughly once in a lifetime. Only a tiny fraction of the 100billion stars in a typical galaxy have the capacity to become a supernova, being restricted to those having high mass and rare kinds of binary stars containing white dwarfs. [3] Early discoveries [ edit ] More recently, astronomers have been getting excited about a newly discovered supernova in the Pinwheel Galaxy. Designated SN 2023ixf and located some 21 million light-years from Earth the new supernova is attracting the attention of both professional and amateur astronomers worldwide who are turning their telescopes and cameras toward the spot to observe this somewhat rare phenomenon. Additional resources Electron capture by magnesium in a degenerate O/Ne/Mg core (8–10 solar mass progenitor star) removes support and causes gravitational collapse followed by explosive oxygen fusion, with very similar results.

supernova

Type II supernova sub-categories are classified based on their light curves, which describe how the intensity of the light changes over time. The light of Type II-L supernovas declines steadily after the explosion, while the light of Type II-P supernovas stays steady for a longer period before diminishing. Both types have the signature of hydrogen in their spectra. The second type of supernovae occurs at the end of a single massive star’s lifetime. It is important to note that not all stars “go supernova”; only thosewith at least five times the mass of our sun. After the star has burnt up its reserves, the nuclear fusion in the core comes to a standstill, and the star’s mass begins to flow into its core. Supernova of a supermassive star (Photo Credit: ESO/VISTA/J. Emerson/Wikimedia Commons) Astronomers use Type Ia supernovas as "standard candles" to measure cosmic distances because all are thought to blaze with equal brightness at their peaks.

Supernova searches fall into two classes: those focused on relatively nearby events and those looking farther away. Because of the expansion of the universe, the distance to a remote object with a known emission spectrum can be estimated by measuring its Doppler shift (or redshift); on average, more-distant objects recede with greater velocity than those nearby, and so have a higher redshift. Thus the search is split between high redshift and low redshift, with the boundary falling around a redshift range of z=0.1–0.3, where z is a dimensionless measure of the spectrum's frequency shift. [47] The supernovae of type II can also be sub-divided based on their spectra. While most type II supernovae show very broad emission lines which indicate expansion velocities of many thousands of kilometres per second, some, such as SN 2005gl, have relatively narrow features in their spectra. These are called type IIn, where the "n" stands for "narrow". [61] A small proportion of type Ic supernovae show highly broadened and blended emission lines which are taken to indicate very high expansion velocities for the ejecta. These have been classified as type Ic-BL or Ic-bl. [64]

Word History

Abnormally bright type Ia supernovae occur when the white dwarf already has a mass higher than the Chandrasekhar limit, [91] possibly enhanced further by asymmetry, [92] but the ejected material will have less than normal kinetic energy. This super-Chandrasekhar-mass scenario can occur, for example, when the extra mass is supported by differential rotation. [93] In the re-ignition of a white dwarf, the object's temperature is raised enough to trigger runaway nuclear fusion, completely disrupting the star. Possible causes are an accumulation of material from a binary companion through accretion, or by a stellar merger. There is no formal sub-classification for non-standard type Ia supernovae. It has been proposed that a group of sub-luminous supernovae that occur when helium accretes onto a white dwarf should be classified as type Iax. [94] [95] This type of supernova may not always completely destroy the white dwarf progenitor and could leave behind a zombie star. [96]

The Creators of incredibly beautiful remnants. The result of immense and apparently destructive forces are often quite stunning. Some of the most magnificent stellar objects in existence – the dream of every astronomer to observe in their lifetime – were created by supernovae that occurred hundreds and thousands of epochs ago. A few percent of the type Ic supernovae are associated with gamma-ray bursts (GRB), though it is also believed that any hydrogen-stripped type Ib or Ic supernova could produce a GRB, depending on the circumstances of the geometry. [125] The mechanism for producing this type of GRB is the jets produced by the magnetic field of the rapidly spinning magnetar formed at the collapsing core of the star. The jets would also transfer energy into the expanding outer shell, producing a super-luminous supernova. [112] [126] [127] Eventually, the core gets immensely dense, to the point where it can no longer withstand its own gravitational force. This results in a core collapse, paving the way for a catastrophic and violent explosion, known as a supernova.Think about how massive our sun is, in comparison to its planets, and yet its mass is nowhere near a supermassive star that could end in a supernova. Today’s astronomers are much better prepared for the next supernova than Kepler would have been—or than anyone would have been just a few decades ago. Today’s scientists are equipped with telescopes that record visible light. These instruments will show what a supernova would look like if we could fly close to it and look at it with our own eyes. But we also have telescopes that can record infrared light—light whose colors lie beyond the red end of the visible spectrum. With its longer wavelengths, infrared light can pass more easily through gas and dust than visible light, revealing targets that may be impossible to see with traditional telescopes. The James Webb Space Telescope, for example, records primarily in the infrared. Both visible and infrared light are part of the “electromagnetic spectrum,” but supernovas also emit a different kind of radiation, in the form of subatomic particles called neutrinos—and today we have detectors to snare them, too. As well, astronomers now have detectors that can record subtle ripples in the fabric of spacetime known as gravitational waves, which are also believed to be unleashed by exploding stars.

Origin of supernova

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. (Image credit: NASA/ESA and Jeff Hester (Arizona State University).) Type II supernovas The first type of supernova is associated with binary star systems. Binary stars are two stars that orbit the same point, or center of mass. When one of the stars—a white dwarf(a highly dense star not much bigger than our sun)—steals matter from its companion star as it orbits the axis, it begins to accumulate enormous amounts of matter. This causes the star to eventually explode, resulting in a supernova. Supernova of a binary star(Photo Credit: Wikimedia Commons) The IceCube Laboratory at the Amundsen-Scott South Pole Station in Antarctica is the first gigaton neutrino detector ever built.