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Sunday, 4 March 2012

Fate of a Star as supernovas and mechanism of explosion of supernovas


**Miss Upasana Bhattacharya-  Only Daughter of Professor Pranab kumar Bhattacharya,  Student, Mahamya apartment;  Mahamyatala, 54 NSC Bose Road; Garia, kol-84. WB, India

**ProfessorPranab kumar Bhattacharya MD(cal) FIC Path(ind) Professor and Head of  Department of  pathology,  School of Tropical Medicine;  108, CR Avenue ,KOlkata-73 WB, India Ex Professor and HOD Ophthalmic Pathology RIO kol-73, & of WBUHS and Ex Professor of Institute of Post Graduate Medical Education & Research,244 a AJC Bose Road, Kolkata-20,  west Bengal, India
***Mr.RitwikBhattacharya *** Miss Rupsa Bhattacharya *** Mr Soumyak Bhattacharya BHM, MSc student PUSHA, New Delhi, India ,
***  7/51 purbapalli, Po-sodepur Dist 24 parganas(north) , Kolkata-110,WestBengal, India
**** Mrs. Dalia Mukherjee BA(hons) Cal**** Oaindrila Mukherjee Student **** Mr Debasis Mukherjee BSC(cal)  of Residence  Swamiji Road, south Habra, 24 Parganas(north)   West Bengal,  India
  People and News media says “Some say the world will end in fire; Some say in ice… Some says in 31st December 2012 is end of this world  through a hit of asteroid, some says end of world from Type A Solar storm ”*
What is the fate of this Universe what Nobel Laureates Says?
Probably it will end in ice if we are to believe  2011 Nobel Laureates in Physics”. They have carefully studied several dozen  of exploding stars, called supernovae, in faraway galaxies and have concluded that the expansion of our Universe is speeding up. Source  -  

Cosmos is growing
 It is not the first time that an astronomical discovery has revolutionized our ideas about our Universe. Only a hundred years ago, the Universe was considered to be a calm and a peaceful place, no larger than our own galaxy, the Milky Way. The cosmological clock was ticking reliably and steadily and the Universe was eter­nal. Soon, however, a radical shift changed this picture. At the beginning of the 20th century the American astronomer “Henrietta Swan Leavitt” found a way of measuring distances to far away stars. At the time,  some women astronomers were denied access to the large telescopes, but they were then frequently employed for the cumbersome tasks of analyzing photographic plates taken of these large telescopes. Henrietta Leavitt  had thus  enjoyed enough scope of  analyzing  & she  could  havoc  scope of studying thousands of pulsating stars, they called them “Cepheids”, and found that the brighter ones had longer pulses. Using this information, Leavitt could calculate the intrinsic brightness of Cepheids and it was immediately accepted by  rest of world.  She told ,If the distance of just one of the Cepheid stars is known, the distances to other Cepheids can be established – the dimmer its light, the farther away the star is”. A reliable standard candle thus was born, a first mark on the cosmic yard stick that is still being used today. By making use of Cepheids, astronomers would soon concluded that the “Milky Way” is just one of many galaxies in  our observable Universe. And in the 1920s, the astronomers got access to the world’s then-largest telescope Mount Wilson in California, so they were able to show that almost all galaxies are in fact moving away from us. Wao! It was astonishing discovery in Astronomical science &Physics!. The concept of Red shift.  They were then studying the so-called “redshift”(Z) that occurs when a source of light is receding from us. The light’s wavelength gets stretched, and the longer the wave, the redder becomes its color was the theory behind it. What ever may be, the conclusion was that all the galaxies are rushing away from us and each other, and the farther away they are, the faster they move – this is known  today as Hubble’s law. The Universe is growing[2].

The coming and going of the cosmological constant
What was observed in space time  had already been suggested by theoretical calculations. In 1915, the great Nobel Laureates in physics  Albert Einstein published his General Theory of Relativity, which had been the foundation of our understanding of the Uni­verse ever since the publication. The theory described a Universe that has to either shrink ( Big Crunch)or to expand. It was really a disturbing conclusion for mathematician. This disturbing conclusion was reached about a decade before the discovery of the ever-fleeing  away galaxies. Not even Einstein could reconcile the fact that the Universe was not static( steady State theory of JB Narleiker and Howel). So in order to stop this unwanted cosmic expansion, Einstein  had no other option but to add a constant to his equations that he  himself called the cosmological constant. Later, Einstein would consider the insertion of the cosmological constant was
a big mistake for him. However, with the obser­vations made in 1997–1998 that are awarded the 2011 Nobel Prize in Physics, we can conclude that Einstein’s cosmo­logical constant – put in for the wrong reasons – was actually brilliant one thought in fact. The discovery of the expanding Universe was a groundbreaking first step towards the now standard view that the Universe was created in the Big Bang almost 14 billion years ago. Both time and space began  only then. Ever since, the Universe has been expanding; like raisins in a raisin cake swelling in the oven, But No body still answered what is beyond that Planck’s moment of Big Bang Creation of our universe. Was there another universe? Was there multiple universe?

Stars last too long in the universe.
 For an amateur astronomers/ or theoretical physicist like myself and my brother Rupak, to see any evolution of a star or death of a star, in the course of his/their life time, unless he/they is/are lucky enough to see one star destroying itself in a phenomenon  called supernova or in a nova explosion or turning towards a Red giant . My then  old and  diseased father[ in 2009 April] , late Mr. Bholanath Bhattacharjee and my mom late Mrs Bani Bhattacharya (diseased in may 2006)  of  residence7/51 Purbapali, Po-sodepur,24 parganas(north) kol-110, West Bengal, India ,used to teach our brothers and  only sister in our younger ages, child ages, with their built up notion like this”….. Stars are long lived objects with ages, they are as old as our galaxy is, as old as our universe is and they are symbol of eternity [heaven and hell their Planets are] they may be 2.5 billion years – 3 billion years old from a first generation stars explosions and are almost perfect cosmic mile markers even very close to Big Bang. And many such stars might have habitable planets like our Earth where civilization grew but better form of technological civilization exists there and we intelligent human beings come from there and returns back after our death there according our acts in this planet.   Today we know that looking at a supernova of a very distant star almost at horizon of the universe, or of a Nebula, we can understand the mystery of creation of the Universe, the Big Bang it self. They are really the symbol of the eternity.  Edington suspected, that the nuclear reactions in the interior of the stars are primary sources of energy for it’s luminosity and fusion of hydrogen to make Helium and that can take place in it, in time bound scale for this ranges, from millions to millions years. Our sun has lost it’s brightness by more then 1% from it’s birth, due to change in it’s internal structure for past 107 years. But  the question remains  how these supernovas explode? What is the mechanism behind it?  No physics probably answered it yet. Here may be  some explanations by my brothers Rupak Bhattacharya and Ritwik Bhattacharya  the authors
If we consider the mode of generation of energy in the star, nuclear process provide the only source of energy adequate to keep the stars ongoing luminous. The nuclear fusion in which Hydrogen is built up into Helium, can function sufficient fast at temperature, like those at central core of star (12-25 million degrees). The Helium burning process are important 1) Carbon Nitrogen cycle at which a carbon-12 nucleus (12C) capture proton and is converted into 13C, Nitrogen-4 and nitrogen –15. At a final temperature, a proton leads to a fusion yielding original 12C nucleus to a Helium nucleus .2) The Proton- Proton process, in which protons are built direct Helium nuclei through steps, involving first in production of a deuterium and helium3 nuclei to form Helium4 nucleus and two protons. 3) Carbon burning process where 12C nucleus undergoes fusion reaction in the interior of a star producing neutron, proton, and Alfa particles with huge temperature. The first reaction probably dominates into the star, applicable to more massive stars then Sun. The second and third reaction is applicable for Sun and in less massive stars then Sun respectively. Thermonuclear reactions like those in a hydrogen bomb are powering the Sun in a contained and continuous explosions converting some four hundred millions tons (4x1014 grams) of hydrogen into helium. When we look up in the sky in night and see the stars we see them shining because of distant nuclear fusion in them .But hydrogen fusion can not continue for ever.  Our Sun is ~ 4.7109 years old star. The energy produced in our ordinary star Sun in each second, is equivalent to the destruction of 41/2 millions tons of hydrogen mass in every second, a mere fleabite compared with the mass of the Sun which is two thousand billion and billion tones. In the Sun or in any other stars, there is limited so much hydrogen in it’s hot interior. Although Helium is predominating as net fusing of Hydrogen, other elements like “carbon”, “Iron”, “L element” “Manganese” “Chromium”, EU, yttrium, Magnesium, SR, Nickel, Osmium are also built up in the interior of the stars. Arnett and Truran [Arnett W.D and Truran. JW –Astrophysics.J-Vol157;P339,1969] showed that nuclear reaction net work in the sun when 12C nuclei  began to under go the fusion reaction in the interior of sun many elements are produced such as
12C+12C----  23Na+P+2.238mev----23Mg+ n+2.623mev------20Ne+ 27Al +4.616mev and the reaction goes on endlessly. A large number of computed reactions are possible as the liberated neutron and gamma particles begin reaction with all the nuclear species generated within the hydrogen fusion. In fact Arnett and Truran produced 99 different reactions only in 12C carbon burning net work and  23Na,20Ne, 24Mg,27Al,29Si, and some31P  elements are also produced. Beside these Li, Be, B ( Known as leptons)are also produced in the stars due to hydrogen burning. Another more most elementary particles are produced in huge quantities. They are Neutrinos or ghost particles due to hydrogen burning procedure ( Professor Pranab Bhattacharya & Mr. Rupak Bhattacharyya). Conversion of hydrogen into helium in the center of the stars or of the Sun, not only accounts for Sun’s brightness in photons of visible light. It also produces a radiance of a more ghostly kind. The sun glows faintly in neutrinos  , which like photons, weight nothing and travel at speed of light. Neutrinos emitted from Sun carry an intrinsic angular momentum or spin while photons has no spin. Matter is transparent to neutrinos which can pass effortlessly through the earth and through the Sun. Only a tiny fraction of them is stopped by intervening matter. As you look up our sun, a billions neutrinos pass through your eye ball. They are not stopped by Retina as ordinary photons do ,but continue unmolested through the back of your head. The curious part is that if at night if I look down at ground, towards the place where sun would be, almost exactly same numbers of solar neutrinos pass through my eye ball, pouring through an interposed earth which is as transparent to neutrinos as a plane of clear glass is to visible light. Neutrinos on very rare occasion convert chlorine atoms into argon atoms with the same number of protons and neutrons. Davis first used a beautiful technique of Pontecours and Alvarez based on the reaction  37C1(V,e-)37Ar to place an upper limit on the solar neutrinos flux on earth
The previous view regarding the “L atoms elements” was that  each star makes it’s own share of these “L atoms elements”i.e (autogenously origin). But the concept of autogenic view has been now abandoned, because highest abundance values for stellar Li & Be have shown to be not larger than interstellar upper limit. The formation of each “L atoms” requires the acceleration of about 1erg fast proton. To account auto genetically for lithium abundance in T. Tauri stars (L1/H=109), the time integrated amount production of energy into particle acceleration must be comparable with gravitational release, implying an unlikely high efficiency for acceleration mechanism. So nuclear mechanism is responsible for generation of “L atoms” in the star. It involves high-energy process (Thermonuclear reactions). These L atoms” can be formed in two different ways within the stellar interiors. By the collision of incident light particles on the heavier atoms of interstellar gas (For instance fast protons on stationary C, N, O) or the reverse (for instance fast C, N, O on hydrogen at rest). In the first case the Products “ L atoms are to remain in rest, while in the second case, the products are moving at a velocity comparable with that of cosmic rays. The fate of  “ L atoms” generated by fast protons on stationary C, N, O stationary atoms and are all rapidly thermalised and become part of ISM.
  “L atoms” generated by reverse process have a fate which depends on the initial energy of “L atoms”. L atoms with energy E<0.2 Gev nucleon-1 will stop in galactic gas (ISM) while L atoms with E > 0.3Gev neucleon-1 will suffer nuclear transformation of various elements in the stellar interior.
Analysis of Old stars can give us some idea that heavy elements are produced in the interior of the stars and are subsequently ejected into the ISM either through the supernova explosion or through stellar winds or through cosmic rays. The total mass loss, from all stars in a galaxy will be roughly 1MO per year. A fraction of these accumulate in the galactic nuclei, which are center of the gravitational attraction. The halo of our galaxy is nearly spherical region containing very old stars, which have a smaller content of heavy elements than our sun has. It is usually assumed that some how cloud of gas condensed to form our galaxy and that the halo stars were formed during the collapse process and left with a nearly spherical distribution. These stars are ultra high velocity stars. These stars show weak spectral lines corresponding to abundance of carbon and heavier elements [relative to hydrogen] that are lower than our Sun. Because these stars are oldest in our galaxy quite distinct type of nuclear process have been postulated for different groups of elements. The most abundant nuclei are 32S and 58Fe those can be formed by silicon burning process while 16O, 20Ne,23Na 24Mg,28S may be produced by explosive carbon burning process. When heavier elements notably Sr, Y, Zr, Ba etc require neutron capture on slow time scale, by iron group nucleotide already present in the star. A peculiar type of star 73 DRA has been investigated for many a time. It is full of chromium with europium and strontium. The star showed the presence of Cr, Eu, Sr and also Mn, Fe, Ni, in gaseous form while osmium (z=76) is present in both neutral and ionized form. The importance of these heavy elements is that, some of them such as Iridium, gold, uranium are also produced in the stars in the gamma process of nucleus synthesis [Neutron capture slow process]
 So Helium, L atoms, Carbon, Iron, gold, chromium, nickel, silicon and many other elements are built up in the stellar interior. Although the net fusing of hydrogen into helium dominates however at this stage. Helium builds up in the core. The supply of hydrogen fuel diminishes and eventually becomes in sufficient to provide energy to hold up the strain position. As the energy production decreases, the core of the star contracts and heats up through release of gravitational energy. With a hotter center there is a greater outward pressure and the outer layer of the star expands, so that the star now becomes a RED GIANT. The red giant has a radius hundred times that of a sun. Mean while in the hotter core a new series of fusion reactions begins and with the helium as the fuel many elements like carbon oxygen, neon, magnesium. When helium will exhaust as a fuel, the carbon burning process will start as 12C as a fuel in the star. In any star the internal temperature and density and therefore the rate at which the energy is generated depend sensitively on the opacity of the stellar material or in other words, on the ease with which the photons can escape from the stellar core. In simple terms you can say greater the opacity harder it is for heat to get out making core hotter. Opacities in normal star can be calculated reliably from knowledge for the abundance of the constituent elements and their ionization site

Suernova-: Another important thing in our universe are the supernovas or novas. The supernovas are the explosion of the central core or outer core of a giant massive star. These supernovas are found in the binary star system. A star may end its life cycle either in the form of a RED GIANT or in the form of a white dwarf or in the form of a “ black Dwarf” or in the form of “ neutron Star” or in Black Hole” or in the form of Supernova Explosion”. When the explosion of a star occurs in small scale, we call it Nova. In Big bang concept, apart from hydrogen, a little helium was produced. Every atom of every element had been built up by the nuclear fusion reaction in the stellar pressure cooker. The elements only could arrive in the  interstellar space to mingle in the clouds of forming protostars is through this supernovas  Novas are however quite different from supernovas. Novas occur in binary star system and are powered by silicon or carbon fusion. Supernovas occur in single  associated with old population II stellar system such as elliptic galaxies and in globular clusters. The classical supernovas are therefore a subset of the cataclysmic variable class of objects, which undergoes out bursts with peak luminosity ~ 5x1037 to 5x 1038 ergs S-1 in every 104 to 105 years. Around 10-5 to 10-4 MO material are ejected at velocity typically 1000 Kms-1 at each outburst of supernova. The central system is a semi detached binary stars, containing a white dwarf . Classical supernova out burst was observed in 1901, where as dwarf nova out burst was first observed in 1986.
Supernovas are two types Type-1(SN-I) and Type 2(SN_II) supernovas.  Most astronomers agree that a type 1a supernova starts with a white dwarf — an aging star that crams as much mass as the sun into a volume no bigger than Earth. Most white dwarfs are cold and inert. But if the star has a companion, it will siphon mass off the neighbor star until tipping the scales at about 1.4 solar masses. At that mass, the white dwarf becomes dense and hot enough to initiate an explosion. Mass accreting white dwarfs, in close binary system of stars are Type-1 supernovas, while  low mass (M70t <5MO) binary X ray sources are known as Type II supernovas. Supernovas are the brightest source of IRAS and radio noises. Supernovas are the sources of Cosmic rays also .The bulk of the cosmic rays with high intensity are local cosmic rays and they are derived from many such  supernovas in past distributed through our galactic disks. Historical supernovas are all too recent and too distant , to be significant contributor of cosmic rays. In 6th  April of 1947 ( almost 9 years before I was born in this planet) a supernova, in a satellite of famous Whirlpool galaxy called MSI was observed . A star in that galaxy  had a sudden maximum Brightness and following that within a few weeks  it faded out  and had been then overlooked. A supernova appears in the spiral galaxy  on an average once in  400 years approximately. The most distant supernova so far detected is 10 billion light years away from our earth,  the first generation star it was. How much my father was correct, I often think it today
 The remnants of the Exploding stars or supernovas are called Supernova remnants. They are easily identified by radio astronomers up to millions years after their explosion. The optical ultra violets and X-rays continue are produced by the supernova explosion and interaction of the resting debris (Supernova remnants), with dense Circumstellar gas shell, previously formed by the stellar wind of the progenitor supernova. L. Stavely Smith , in 1992 showed the birth of the radio noise supernova remnants SNR1987A, following radio outbursts of Supernova 1987A[ Nature Vol-355 1992]. In the mid 1990, about 1200 earthen days after the supernova radio emission was detected at frequencies 843 MHZ and 8.6 GHG and this radio emission was within 0.5 arsc of the optical supernovas
Although both young and old star can give rise to supernovas, the massive stars, none of which is thought to live more than several million years, are also thought to end their life in this way. Supernovas can occur in conjunction with their satellite planet or binary stars. One of You among readers of our thesis may obviously ask me that in what conditions could a star or a planet can survive such a nearby explosion? Several simplifying assumption can be made to answer this question.
1)   The time of mass ejection will be small compared with the orbiting period
2) The mass of the second star or planet will be smaller than that of the pre- supernova star. The first simplification was based on that the ejection velocity of major fraction of the matter from a supernova will be comparable with or larger than its initial escape velocity from the pre- supernova star. Because the binary number is necessarily at larger radius, its orbital velocity will be less than the average ejection velocity. If the combined mass is reduced to less than a half by the supernova, in the limit, where the mass ejection is sudden and where the mass of the secondary is small, the system will un-banned regardless of the effects of the collision of the ejected matter within the satellite of the planet.
   The fractional mass ejection by supernova is known for the thermonuclear supernova model. No remnant of star remain on the other hand models of neutron star supernova, predicts various fractional mass ejection depending on mass and structure of the initial star. But all the models, be it thermonuclear or neutron star or cataclysmic variables predicts a small fractional mass ejection, for the models slightly more massive mass than C.S. Limit, and are self consistent, in that the mass of the remnant neutron star does not exceed current stability limit. A star of initial mass 1.5MO leaves a remnant neutron star of mass 1MO. The link between supernova explosion and formation of a neutron star has to be rather established even if Type II supernovas are expected to leave to a stellar component. Only five example of Pulsar Supernova remnant association are known on our galaxy and in large Megallenic cloud.
 Previously as we the authors told, that mass accreting white dwarf in close binary system can be considered to be Type-1 supernovas progenitors. Low mass (Mtot≈5MO) binary X ray sources( Known as type II supernovas) appear to be descendents of cataclysmic variables and thus they have been produced by collapse of a mass  accreting white dwarf. The fashionable model of explaining the out burst involves central deflagration of a white dwarf in close binary system living no remnant. But this model implies a unique configuration and do allow for variation. Slow supernovas show higher peak of luminosity, higher velocity in their ejecta and slower decline in their light curve. Fast Supernovas are dimmer velocities of expanding material are low and light curve decay is faster.

Super hemps_: They are periodic increase in Brightness (up to 40%) that are observed during occasional super out bursts lasting about 12 days, that are additional to normal outbursts of a subclass of white dwarf Nova. Dwarf Nova’s are characterized by two distinct class of out bursts. Normal  outbursts of duration ~2 days and less frequent super outbursts which lasts for ~12 days. During super outbursts, super hemps are observed which modulate the visible light by≤40% with a period 3-7% longer than biniary period.

Mechanism of Explosion in Supernova-a mechanism proposed by Professor Pranab Kumar Bhattacharya Mr, Rupak Bhattacharya_:
 What is the mechanism of a supernova explosion in a star? It is not known and yet explained very well. Possibly one of the standard mechanisms of a supernova is the collapse& out going shock due to collapse, leaving behind a neutron star, is the collapse of the iron core of a massive star. During the initial phase of the collapse, a sizable portion of the star transfers into neutrinos with emissions of ve energy≤10Mev.[Rupak Bhattacharya and professor Pranab Kumar Bhattacharya’s theory] The collapse phase lasts until the infiltrating matter becomes opaque to neutrinos. A few~1056 ve neutrinos are emitted during this phase. As the collapsed core reaches nuclear matter densities, an out going shock develop. When the shock reaches the dense layer that are still transparent to neutrinos, another ~1056V mostly Ve are expected to be emitted. The second one of the bursts , produce neutrinos with an average energy~10Mev5~10. The whole process lasts much less than a second. The remainder of the gravitational energy (~2x1053ergs) is emitted in the form of vv pairs of all flavors. Although the neutron star contain vv pairs of very high energy (100Mev), the only low energy one is eliminated, because the neutrinos mean the free path, is strongly energy dependent. The energy is larger for µ, e R neutrinos (Rupak neutrinos). There are dozen of neutrinos particles of 7-35 mev mass in that energy. There charges is smaller than about 10-17 times the charge of electron. [Such a neutrinos is R particles or R neutrinos-a near zero mass, conceptualized by Rupak Bhattacharya and hence nomenclatured  here according to his name]
 What is the Key thermonuclear feature of an expanding star that will end it in supernovas? The ignition of helium in the hydrogen as soon as exhausted, in core of a low mass star, in the presence of a degenerate electron gas which is providing the bulk of the pressure support of the star, the expansion of the star core starts. Because pressure of such a gas does not increase ,substantially when temperature rises, where as the rates of thermonuclear reaction increase dramatically with increasing temperature, a brief run away in thermonuclear activity ensues. After this the star in there core quickly expands. After only a small degree of nuclear burning to an adjusted configuration, where burning can proceed in hydrostatic equilibrium with subsequent discovery of very effective cooling of stellar interior due to neutrinos emission, it has become apparent that intrinsically more explosive nuclear fuel namely 12C and16O may also ignite in a very degenerate electron gas and that in that case, the run away in nuclear reaction may be great enough completely to disrupt the star via a thermonuclear explosion. The high temperature of the explosion which lasts only a fraction of second produces such a high degree nuclear processing that expelled thermonuclear product are vastly different than the composition of the mass zone of the star, before the explosion. The key thermonuclear feature of explosive burning is that several fuel combust at temperature considerably higher than those at which same fuel burn in an object in hydrostatic equilibrium with considerable effect in abundances of ejected matter. The over heating may result either from the fact that the fuels first ignite in a degenerate electron gas for the non central mass zones from the compression heating, produced as a strong pressure and have propagation outward fro an expanding core. In either case large amount of thermal energy are liberated in a time short compared with star’s ability to compensate hydro dynamically, with the result that the entire star may be given with positive energy sufficient to disrupt it in explosion.
Before the explosion, the gas is virtually half and consisted of 12C and 16O. The first indication of importance of dynamics of the explosion of the final nuclear product came in a study of carbon burning phenomenon of Arnet, who established a numerical scheme for solving the nuclear reaction net work that result when12C nuclear reaction began to undergo the fusion reaction in the interior of the star before supernova[ Arnet W.D & Truran J.W Astrophysics Jpurnal V157;P339;1969]
12C+12C        23Na+P+2.238mev             23Mg+tn    -2.623mev         20 Net+α+4.616Mev
A large numbers of computed reactions are thus possible, as the  fusion reaction liberated proton, neutron, neutrinos and alpha particles and began to react with all of the nuclear species generated within the gas. Before the explosion, the gas is virtually half and half of the 12C and 16O as produced in previous epoch on helium burning plus 2% of 18O which is the result of earlier conversion, within the same star, of all of the original CNO nuclei in to 18O by hydrogen burning and helium burning in turn. Carbon burn furiously for about 1/10th  of second at which time reactions are frozen by falling temperature, associated with vigorous expansion of gas. Most of the carbon and virtually all of the initial oxygen remain unburned, so that the final ratio of 12C/24Mg matches the solar ratio. More subsequently the nuclei  2One,23Na, 24Mg, 26Mg,27Al, 29Si and 3O and some time 31P are produced. So today whatever elementary nuclei  we know in our earth or in earth’s atmosphere is the fusion-burning product of a supernova explosion in a dying star.
1987 A Supernova-:  and Recently detected Supernovas[  Picture by


In our galaxy there were evidences of eight supernovas. They are in the years 185,393,1006 AD and in 1054,1181,1572,1604,and very recently one is 1987.Only supernovas 1006,1572,1604 were observed by European Astronomers. The supernova of 1054 was as a cloudy patch, and remains still as Crab nebulae as the legs of a crab. It is the remnant of that supernova. It is at a distance of 4500 light years away and is left over gases that has a diameter of about 6 miles. [Mitra A.K- Space Light first year 2nd quarter1997 P10]. Supernova 1987A occurred in the large Megaloionic Cloud (MLC).It was a supernova of a giant star SK69202 that exploded. The star was the star of multiple star systems instead of a binary star system. SN 1987a was 18 solar mass blue giant Sanduleak -69° 202a, a mere 0.000168 billion light-years distant. This star had lost a considerable mass of M20O due to the explosion. The other members of this giant multiple system is now visible as supernova remnant. The SK 69202 was probably a red super giant 104—105 years ago. The outer envelop, blue star giant progenitor star is preserved during the rapid supersonic un turbulence outflow of the supernova. The huge amount of R- neutrinos (Rupak Particles) are now emitted by this 1987A supernova proposes the formation of a neutron star, inside this supernova some have reported that central region of this supernova was a central pulsar. However the history of this supernova 1987A is today 23 years old. In the supernova 1987A there is evidence of presence of H3+ in the envelope or in the shell of it. The infrared L window spectrum of supernova 1987A is between 2.95-4.15um were obtained by hydrogen re combination line ( Mcikle.W. PS Not.R. Astr Society V283;P193-223;1989). But from 110 days onward there were an evidence of hydrogen recombination line between spectrum 3.41-3.53um. These were possibilities in wave length at which H3+ announces most strongly presence of a planet like Jupiter (Okata.T etal- Astrophysics J-Vol351;P253-56;1990).When the first explosion of supernova 1987A happened there were a brief initial outburst of radio emissions that lasted for more than a few days. The expanding Nebulae were set into motion by the ejection and cooling of ejected material and its interaction with circumstellar material that surrounded the progenitor& was then non visible at the available radio frequencies. Evolution of radio-supernova remnant over the last years provided us the information about the progress of the expanding supernova remnant. The nature of its unusual progenitor star which was first a   red giant and then a blue giant, before it exploded. In the red giant phase, the star threw off a dense slow moving wind which was succeeded by a more tenuous but faster wind from the blue giant. The circumstellar material of the progenitor at the moment of the explosion there fore consisted of a hot thin gas- cocooned inside a cooler thicker shell with a supersonic shock wave created at the boundary, as the blue  giant wind ran into red giant wind. The first brief flash of radio emission was a very minor part of the initial supernova outbursts and was probably attributable to the propagation of shock wave from explosion through the thin material immediately surrounding what had been progenitor star.
 Supernova are now routinely observed in other galaxies . During the life time of a galaxy about 10 billion years, a hundred millions of stars exploded. Amongst them, David Helfend and Knoxlong reported an extremely intense burst of hard X-ray and gamma rays which was also recorded by nine interplanetary space crafts and which was also probably Supernova N49 remnant in large Megellanic Cloud [ MLC is a small satellite galaxy of Milky Way 18,0000 light year distant)[ Nature march5,1979 & decemb6 1979]. The recent nova which had been detected in Cygx-1 galaxy. It was Nova V404 cygni- Low mass x ray binary emits x ray and x ray behavior is similar to black hole system. In April 6,1947 discovered a supernova in a satellite of famous whirlpool galaxy M51- A star suddenly had maximum brightness and had then overlooked. On 9th January 2008, while viewing of galaxy NGC 2770 an unexpected transient burst of Xray was detected in one of the galaxies spiral arm. Further observation showed that the burst was a first sighting of new type of Ibc supernova duly was named as SN200D.  Most distant Supernovae are super bright, and that makes them easy to see from far away. Very far away. 11 Billion Light years to be exact from earth. almost at time of birth of first generation stars and galaxy.

 Pulsar formation is generally attributed to supernova events and two pulsars are till associated with known supernova events. They are Crab Nebulae pulsar NP0532 and Vela. Other pulsars are close enough to supernova remnants to suggest an association but only if they are moving away from the remnants at velocities of order 103 Km/second. Fowler KA and Hogel F in 1963 suggested that supernova core may well be too massive to form a gravitationally  stable object(neutron Star) and gravitationally Collapsing Object(black Hole too). They suggested that systemic ejection of Radio luminous material from galaxy could be caused by symmetrical process occurring in the collapse of very massive objects, thus the more massive core could fission into several less massive objects. The same process can be applied to supernova events where core fragments into some distribution of neutron stars” Black holes’ and general debris[ Fowler WA, Hoyel F Nature 197; 533;1963]. There is a pulsar PSR 1509-58 located near the center of radio supernova remnant MSH 15-52, a supernova remnant of supernova AD1054. This pulsar is young only about 1700 years. The near coincidence of this age with that of supernova of AD 185 strongly suggest that PSR1509-58 was born in AD1054 supernova explosion.

 Why Supernovae? – the new measure of the Universe When Einstein got rid of the cosmological constant and surrendered to the idea of a non-static Universe, he related the geometrical shape of the Universe to its fate. Is it open or closed, or is it something in between – a flat Universe? An open Universe is one where the gravitational force of matter is not large enough to prevent the expansion of the Universe. All matter is then diluted in an ever larger, ever colder and ever emptier space. In a closed Universe, on the other hand, the gravitational force is strong enough to halt and even reverse the expansion. So the Universe eventually would stop expanding and fall back together in a hot and violent ending, a Big Crunch. Most cosmologists,  and  I myself however, would prefer to live in the most simple and mathematically elegant Universe: a flat one, where the expansion is believed to decline. The Universe would thus end neither in fire nor in ice. But there is no choice left by laws of the Universe. If there is a cosmological constant, the expansion will continue to accelerate, even if the Universe is flat.2011 Physics Nobel Laureates expected to measure the cosmic deceleration, or how the expansion of the Uni­verse is slowing. Their method was in principle the same as the one used by astronomers more than six decades earlier: to locate distant stars and to measure how they move. However, that is easier said than done. Since Henrietta Leavitt’s days many other Cepheids have been found that are even farther away. But at the distances that astronomers need to see, billions of light years away, Cepheids are no longer visible. The cosmic yardstick needed to be extended. Supernovae – star explosions – became the new standard candles. More sophisticated telescopes on the ground and in space, as well as more powerful computers, opened the possibility in the 1990s to add more pieces to the cosmological puzzle. Crucial were the light-sensitive digital imaging sensors – charged-coupled devices or CCD – the invention by  Willard Boyle and George Smith who were awarded Nobel Prize in Physics in 2009. White dwarfs exploding  the newest tool in the astronomer’s toolbox is a special kind of star explosion, the type Ia supernova. During a few weeks, a single such supernova can emit as much light as an entire galaxy. This type of supernova is the explosion of an extremely compact old star that is as heavy as the Sun but as small as the Earth – a white dwarf. The explosion is the final step in the white dwarf’s life cycle. White dwarfs form when a star has no more energy at its core, as all hydrogen and helium have been burned in nuclear reactions. Only carbon and oxygen remain. In the same way, far off in the future, our Sun will fade and cool down as it reaches its end as a white dwarf. A far more exciting end awaits a white dwarf that is part of a binary star system, which is fairly common. In this case, the white dwarf’s strong gravity robs the companion star of its gas. However, when the white dwarf has grown to 1.4 solar masses, it no longer The nuclear fusion products emit strong radiation that increases rapidly during the first weeks after the explosion, only to decrease over the following months. So there is a rush to find supernovae – their violent explosions are brief. Across the visible Universe, about ten type Ia supernovae occur every minute. But the Universe is huge. In a typical galaxy only one or two supernova explosions occur in a thousand years. In September 2011, we were lucky to observe one such supernova in a galaxy close to the Big Dipper, visible just through a pair of regular binoculars. But most supernovae are much farther away and thus dimmer. So where and when would you look in the canopy of the sky? manages to hold together. When this happens, the interior of the dwarf becomes sufficiently hot for runaway fusion reactions to start, and the star gets ripped apart in seconds.

From the planet the earth here to eternity
 So what is it that is speeding up the Universe? It is called dark energy and is still a challenge for physics, a riddle, that no one has managed to solve yet of what it is composed of. Several ideas have been however proposed. The simplest is to reintroduce Ein­stein’s cosmological constant, which he once rejected. At that time, he inserted the cosmological constant as an anti-gravitational force to counter the gravitational force of matter and thus create a static Universe. Today, the cosmological constant instead appears to make the expansion of the Universe to accelerate. The cosmological constant is, of course, constant, and as such does not change over time. So dark energy becomes dominant when matter, and thus its gravity, gets diluted due to expansion of the Universe over billions of years. According to scientists, that would account for why the cosmological constant entered the scene so late in the history of the Universe, only five to six billion years ago. At about that time, the gravitational force of matter had weakened enough in relation to the cosmological constant. Until then, the expansion of the Universe had been decelerating. The cosmological constant could have its source in the vacuum, empty space that, according to quantum physics, is never completely empty. Instead, the vacuum is a bubbling quantum soup where vir­tual particles of matter and antimatter pop in and out of existence and give rise to energy. However, the simplest estimation for the amount of dark energy does not correspond at all to the amount that has been measured in space, which is about 10120 times larger (1 followed by 120 zeros). This constitutes a gigantic and still unex­plained gap between theory and observation – on all the beaches of the world there are no more than 1020 (1 followed by 20 zeros) grains of sand. It may be that the dark energy is not constant after all. Perhaps it changes over time. Perhaps an unknown force field only occasionally generates dark energy. In physics there are many such force fields that collectively go by the name quintessence, after the Greek name for the fifth element. Quintessence could speed up the Universe, but only sometimes. That would make it impossible to foresee the fate of the Universe. Whatever dark energy is, it seems to be here to stay. It fits very well in the cosmological puzzle that physicists and astronomers have been working on for a long time. Accord­ing to current consensus, about three quarters of the Uni­verse consist of dark energy. The rest is matter. But the regular matter, the stuff that galaxies, stars, humans and flowers are made of, is only five percent of the Universe. The remaining matter is called dark matter and is so far hidden from us. The dark matter is yet another mystery in our largely unknown cosmos. Like dark energy, dark matter is invisible. So we know both only by their effects – one is pushing, the other one is pulling. They only have the adjective “dark” in common.[2]

1]” Did our universe started in a Big Bang gospel or Just Be?” Authors: ProfessorPranab Kumar Bhattacharya, Mr. Rupak Bhattacharya,  Mr. Ritwik Bhattacharya  Mrs. Dalia Mukherjee & Miss UpasanaBhattacharya in the chapter” Fate of a Star” once published at as E book in July 2004. The Website  had been surrendered to star Dust Company in 2010 and the same E book No more available there.

2]Written in the stars: THE NOBEL PRIZE IN PHYSICS 2011

 By Science Editors Lars Bergström, Olga Botner, Lars Brink, Börje Johansson, The Nobel Committee for Physics/The Royal Swedish Academy of SciencesEditor: Annika Moberg The Royal Swedish Academy of Sciences THE NOBEL PRIZE IN PHYSICS 2011 THE ROYAL SWEDISH ACADEMY OF SCIENCES HTTP://KVA.SE

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Acknowledgement- To our late parent  diseased late Mr. Bholanath Bhattacharya and  late Mrs Bani Bhattacharya of residence 7/51 purbapalli, Po-Sodepur, Dist 24 parganas (north) , Kolkata-110,WestBengal, India,  for their initial teaching  for us about the universe, Big Bang and eternity 
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