Dal R`El and Gwyndala race against time to save their friends, their ship, new alien species and an entire planetary system before a supernova destroys them all as they battle a deadly new enemy who will stop at nothing to destroy the Protostar and change the course of history! In the modern universe, ancient asymptotic giant stars ast (AGB) are the main source of process element dust, oxides and carbon. [161] [170] However, in the early universe, before the formation of AGB stars, supernovae could be the main source of dust. [171] Type Ib supernovae are the most common and result from WC-type Wolf-Rayet stars, which still have helium in their atmosphere. For a narrow range of masses, stars continue to evolve before reaching core collapse to become WO stars with very little helium remaining, and they are the precursors to Ic-type supernovae. [110] The light curves of type II supernovae are characterized by a much slower decline than that of type I, of the order of 0.05 orders of magnitude per day,[135] outside the plateau phase. The visual luminous flux is dominated by kinetic energy rather than radioactive decay for several months, mainly due to the existence of hydrogen in the ejecta of the atmosphere of the supergiant progenitor star. During the initial destruction, this hydrogen is heated and ionized. Most Type II supernovae exhibit an elongated plateau in their light curves as this hydrogen recombines, emits visible light, and becomes more transparent. This is followed by a decaying light curve driven by radioactive decay, although it is slower than Type I supernovae due to the efficiency of conversion to light throughout the hydrogen. [55] The last supernova observed directly in the Milky Way was Kepler`s supernova in 1604, but more recent supernova remnants have been found. Supernova observations in other galaxies suggest that they occur in the Milky Way, on average, about three times per century. These supernovae would almost certainly be observable with modern astronomical telescopes. The most recent naked-eye supernova was SN 1987A, the explosion of a blue supergiant star in the Large Magellanic Cloud, a satellite of the Milky Way.

Supernova discoveries were reported to the Central Bureau of Astronomical Telegrams of the International Astronomical Union, which sent a circular with the name it assigned to the supernova. The name is formed from the SN prefix, followed by the year of discovery, supplemented by a one- or two-digit designation. The first 26 supernovae of the year are capitalized from A to Z. After that, lowercase pairs are used: aa, ab and so on. For example, SN 2003C is the third supernova reported in 2003. [49] The last supernova of 2005, SN 2005nc, was the 367th (14 × 26 + 3 = 367). Since 2000, professional and amateur astronomers have found several hundred supernovae each year (572 in 2007, 261 in 2008, 390 in 2009; 231 in 2013). [50] [51] A historical mystery concerned the energy source that can sustain the optical glow of the supernova for months. Ejecta gases would quickly weaken without energy to keep them warm. Some have considered the rotational energy of the central pulsar as a source.

Although the energy that initially drives each type of supernova is released in a timely manner, the light curves are dominated by the subsequent radioactive heating of rapidly expanding ejecta. The highly radioactive nature of ejecta gases was first calculated in the late 1960s on solid nucleosynthetic bases, and this has since proven correct for most supernovae. [127] It was not until 1987A that direct observation of gamma lines clearly identified the most important radioactive nuclei. [128] These supernovae, like Type II supernovae, are massive stars undergoing core collapse. However, stars that become type Ib and Ic supernovae have lost most of their outer shells (hydrogen) due to strong stellar winds or interaction with a companion. [108] These stars are known as Wolf-Rayet stars and occur at moderate to high metallicity, where winds driven by the continuum cause sufficiently high rates of mass loss. Observations of the Ib/c supernova do not agree with the observed or expected presence of Wolf-Rayet stars. Alternative explanations for this type of core collapse supernova include stars that have been deprived of their hydrogen by binary interactions.

Binary models provide better agreement with observed supernovae, provided that no suitable double helium stars have ever been observed. [109] Since a supernova can occur whenever the mass of the star at the time of core collapse is small enough not to cause a complete relapse into a black hole, any massive star can lead to a supernova if it loses enough mass before core collapse occurs. Since supernovae are relatively rare events within a galaxy that occur in the Milky Way about three times a century,[37] getting a good supernova sample to study requires regular monitoring of many galaxies. Today, amateur and professional astronomers find several hundred each year, some close to maximum brightness, others on old astronomical photographs or plates. Supernovae in other galaxies cannot be predicted with appreciable accuracy. Usually, when they are discovered, they are already underway. [38] To use supernovae as standard candles for distance measurement, it is necessary to observe their maximum brightness. It is therefore important to discover them before they reach their maximum.

Amateur astronomers, vastly outnumbered by professional astronomers, have played an important role in the search for supernovae, usually looking at some of the nearest galaxies through an optical telescope and comparing them to previous photos. [39] The Milky Way`s next supernova is likely to be detectable even if it occurs on the other side of the galaxy. It is likely to be created by the collapse of a discrete red supergiant, and it is very likely that it has already been catalogued in infrared records such as 2MASS. There is less chance that the next core collapse supernova will be produced by another type of massive star, such as a yellow hypergiant, a bright blue variable, or Wolf-Rayet. The probability that the next supernova will be of type Ia produced by a white dwarf is calculated to be about one-third of the probability of a supernova of core collapse. Again, it should be observable wherever it occurs, but it is less likely that the precursor was ever observed. We don`t even know exactly what a Type Ia precursor system looks like, and it`s hard to detect them beyond a few parsecs. The total rate of supernova in our galaxy is estimated to be between 2 and 12 per century, although we haven`t seen one in several centuries. [126] Calcium-rich supernovae are a rare type of very fast supernovae with exceptionally strong calcium lines in their spectra. Models suggest that they occur when matter is accreted by a helium-rich companion rather than a hydrogen-rich star. Because of the helium lines in their spectra, they may look like Ib-type supernovae, but they are thought to have very different ancestors. [58] The collapse of the core of some massive stars may not result in a visible supernova.

This occurs when the initial collapse of the core cannot be reversed by the mechanism causing an explosion, usually because the core is too massive. These events are hard to spot, but major polls have uncovered potential candidates. [124] [125] The red supergiant N6946-BH1 in NGC 6946 experienced a modest explosion in March 2009 before disappearing from view. Only a faint infrared source remains at the star`s location. [126] It is now proposed that more massive red supergiants do not explode as supernovae, but return to warmer temperatures. Several type IIb supernova progenitors have been confirmed, and these were K and G supergiants as well as a supergiant A. [155] Yellow hypergiants, or LBVs, are proposed precursors to Type IIb supernovae, and almost all Type IIb supernovae close enough to be observed have shown such progenitors. [156] [157] A near-Earth supernova is a supernova close enough to Earth to have a noticeable impact on its biosphere. Depending on the type and energy of the supernova, it could be up to 3,000 light-years away. In 1996, the theory was put forward that traces of past supernovae on Earth could be detectable in rock layers in the form of metallic isotopic signatures. The accumulation of iron-60 was reported later in the rocks of the deep seabed of the Pacific Ocean. [182] [183] [184] In 2009, elevated nitrate ions were found in the ice of Antarctica, coinciding with supernovae 1006 and 1054.

The gamma rays of these supernovae may have increased atmospheric nitrogen oxides trapped in ice. [185] Towards the end of the 20th century, astronomers increasingly turned to computer-controlled telescopes and CCDs to hunt down supernovae. Although such systems are popular among hobbyists, there are also professional facilities such as the Katzman Automatic Imaging Telescope. [40] The Supernova Early Warning System (SNEWS) project uses a network of neutrino detectors to provide early warning of a supernova in the Milky Way. [41] [42] Neutrinos are particles produced in large quantities by a supernova, and they are not significantly absorbed by interstellar gas and dust in the galactic disk. [43] Compared to the entire history of a star, the visual appearance of a supernova is very short, sometimes extending over several months, so the chances of observing a star with the naked eye are about once in a lifetime. Only a tiny fraction of the 100 billion stars in a typical galaxy has the ability to become a supernova, limited to those with high mass and rare types of binary stars containing white dwarfs. [1] Ultra-stripped supernovae occur when the exploding star has been (almost) scratched towards the metallic core by mass transfer in a nearby binary system. [114] [115] As a result, very little material is ejected from the exploding star (approx.