Katika karatasi zilizochapishwa hivi majuzi, watafiti wamekadiria kiwango cha kuanguka kwa msingi wa supernova katika Milky Way kuwa matukio 1.63 ± 0.46 kwa karne. Kwa hivyo, kwa kuzingatia tukio la mwisho la supernova, SN 1987A ilizingatiwa miaka 35 iliyopita mnamo 1987, tukio linalofuata la supernova katika Milky Way linaweza kutarajiwa wakati wowote katika siku za usoni.
Life course of a nyota & supernova
Kwa kiwango cha wakati cha mabilioni ya miaka, stars undergo a life course, they are born, age and finally die with explosion and subsequent dispersal of star materials into interstellar nafasi as dust or cloud.
Maisha ya a nyota begins in a nebula (cloud of dust, hydrogen, helium and other ionized gases) when the gravitational collapse of a giant cloud give rise to a protostar. This continues to grow further with accretion of gas and dust until it reaches its final mass. The final mass of the nyota determines its lifetime as well as what happens to the star during its life.
Vyote stars derive their energy from nuclear fusion. The nuclear fuel burning in the core creates strong outward pressure due to the high core temperature. This balances out the inward gravitational force. The balance is disturbed when the fuel in the core runs out. Temperature drops, outward pressure diminishes. As a result, the gravitational force of the inward squeeze becomes dominant forcing the core to contract and collapse. What a star finally ends up as after collapse depends on the mass of the star. In the case of supermassive stars, When the core collapses in a short span of time, it creates enormous shock waves. The powerful, luminous explosion is called supernova.
This transient astronomical event occurs during the last evolutionary stage of a star and leave behind supernova remnant. Depending on the mass of the star, the remnant could be a neutron star or a nyeusi shimo.
SN 1987A, supernova ya mwisho
The last supernova event was SN 1987A which was seen in southern sky 35 years ago in February 1987. It was the first such supernova event visible to the naked eye since Kepler’s in 1604. Located in the nearby Large Magellanic Cloud (a satellite galaxy of the Milky Way), it was one of the brightest exploding stars seen in more than 400 years that blazed with the power of 100 million suns for several months and provided unique opportunity to study the phases before, during, and after the death of a star.
Utafiti wa supernova ni muhimu
Study of supernova is helpful in several ways such as measuring distances in nafasi, understanding of expanding ulimwengu and the nature of stars as the factories of all the elements that make everything (including us) found in the ulimwengu. The heavier elements formed as a result of nuclear fusion (of lighter elements) in the core of stars as well as the newly created elements during core collapse get distributed throughout nafasi during supernova explosion. The supernovas play a key role in distributing elements throughout the ulimwengu.
Unfortunately, there has not been much of opportunity in the past to observe and study supernova explosion closely. Close observation and study of supernova explosion within our home galaxy Milky Way would be remarkable because the study under those conditions could never be conducted in laboratories on the Earth. Hence the imperative to detect the supernova as soon as it begins. But, how will one know when a supernova explosion is about to begin? Is there any early warning system for impeding supernova explosion?
Neutrino, kinara wa mlipuko wa supernova
Karibu na mwisho wa kipindi cha maisha, nyota inapoishiwa na vipengele vyepesi kama mafuta ya muunganisho wa nyuklia unaoiwezesha, msukumo wa ndani wa mvuto hutawala na tabaka za nje za nyota huanza kuanguka ndani. Kiini huanza kuporomoka na katika milisekunde chache kiini hubanwa sana hivi kwamba elektroni na protoni huchanganyika na kuunda nyutroni na neutrino hutolewa kwa kila neutroni iliyoundwa.
The neutrons thus formed constitute a proto-neutron star inside the core of the star upon which rest of the star fall down under intense gravitational field and bounce back. The shock wave generated disintegrates the star leaving the only core remanent (a neutron star or a nyeusi shimo depending on the mass of the star) behind and rest of the mass of the star disperses into interstellar nafasi.
mlipuko mkubwa wa neutrinos produced as a result of gravitational core-collapse escape into outer nafasi unimpeded due to its non-interactive nature with matter. About 99% of the gravitational binding energy escape as neutrinos (ahead of photons which are trapped in the field) and acts as beacon of impeding supernova explosion. These neutrinos can be captured on the earth by the neutrino observatories which in turn act as an early warning of a possible optical observation of supernova explosion soon.
Neutrino zinazokimbia pia hutoa kidirisha cha kipekee cha matukio makubwa ndani ya nyota inayolipuka ambayo inaweza kuwa na athari katika uelewa wa nguvu za kimsingi na chembe za msingi.
Mfumo wa Onyo wa Mapema wa Supernova (SNEW)
Wakati wa supernova ya mwisho ya kuanguka kwa msingi (SN1987A), jambo hilo lilizingatiwa kwa jicho uchi. Neutrinos ziligunduliwa na vigunduzi viwili vya Cherenkov vya maji, Kamiokande-II na jaribio la Irvine-MichiganBrookhaven (IMB) ambalo lilikuwa limeona matukio 19 ya mwingiliano wa neutrino. Hata hivyo, ugunduzi wa neutrino unaweza kuwa kama mwangaza au kengele kwa kuzuia uchunguzi wa macho wa supernova. Kwa hiyo, wachunguzi mbalimbali na wanaastronomia hawakuweza kuchukua hatua kwa wakati ili kujifunza na kukusanya data.
Tangu 1987, unajimu wa neutrino umeendelea sana. Sasa, mfumo wa tahadhari wa supernova SNWatch umewekwa ambao umeratibiwa kutoa kengele kwa wataalamu na mashirika husika kuhusu uwezekano wa kuonekana kwa supernova. Na, kuna mtandao wa uchunguzi wa neutrino duniani kote, unaoitwa Supernova Early Warning System (SNEWS) ambao unachanganya mawimbi ili kuboresha imani katika ugunduzi. Shughuli yoyote ya kawaida huarifiwa kwa seva kuu ya SNEWS na vigunduzi mahususi. Zaidi ya hayo, SNEWS ilikuwa imeboreshwa hadi SNEWS 2.0 hivi majuzi ambayo hutoa arifa za kutojiamini pia.
Supernova ya karibu katika Milkyway
Neutrino observatories spread across the world are aiming at first detection of neutrinos resulting from gravitational core collapse of the stars in our home galaxy. Their success therefore, is very much dependent on the rate of supernova core collapse in the Milky Way.
Katika karatasi zilizochapishwa hivi karibuni, watafiti wamekadiria kiwango cha kuanguka kwa msingi wa supernova katika Milky Way kuwa matukio 1.63 ± 0.46 kwa miaka 100; takribani supernovae moja hadi mbili kwa karne. Zaidi ya hayo, makadirio yanaonyesha kwamba muda kati ya kuanguka kwa supernova katika Milky Way unaweza kuwa kati ya miaka 47 hadi 85.
Therefore, given the last supernova event, SN 1987A was observed 35 years ago, the next supernova event in the Milky Way may be expected any time in the near future. With the neutrino observatories networked to detect the early bursts and the upgraded Supernova Early Warning System (SNEW) in place, the scientists will be in position to have a close look at the next extreme happenings associated with supernova explosion of a dying star. This would a momentous event and an unique opportunity to study the phases before, during, and after the death of a star for a better understanding of the ulimwengu.
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Vyanzo:
- Fataki Galaxy, NGC 6946: What Make this Galaxy so Special? Scientific European. Posted 11 January 2021. Available at http://scientificeuropean.co.uk/sciences/space/the-fireworks-galaxy-ngc-6946-what-make-this-galaxy-so-special/
- Scholberg K. 2012. Utambuzi wa Supernova Neutrino. Chapisha mapema axRiv. Inapatikana kwa https://arxiv.org/pdf/1205.6003.pdf
- Kharusi S Al, et al 2021. SNEWS 2.0: mfumo wa tahadhari ya mapema wa supernova wa kizazi kijacho kwa unajimu wa wajumbe wengi. Jarida Jipya la Fizikia, Juzuu 23, Machi 2021. 031201. DOI: https://doi.org/10.1088/1367-2630/abde33
- Rozwadowskaab K., Vissaniab F., na Cappellaroc E., 2021. Juu ya kiwango cha kuanguka kwa supernovae katika njia ya milky. Kitabu Kipya cha Astronomia 83, Februari 2021, 101498. DOI: https://doi.org/10.1016/j.newast.2020.101498. Preprint axRiv inapatikana kwa https://arxiv.org/pdf/2009.03438.pdf
- Murphey, CT, et al 2021. Historia ya Ushahidi: usambazaji wa anga, kugundulika, na viwango vya nyota za macho ya uchi za Milky Way. Notisi za Kila Mwezi za Jumuiya ya Kifalme ya Astronomical, Juzuu 507, Toleo la 1, Oktoba 2021, Kurasa 927–943, DOI: https://doi.org/10.1093/mnras/stab2182. Preprint axRiv Inapatikana kwa https://arxiv.org/pdf/2012.06552.pdf
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