भर्खरै प्रकाशित कागजातहरूमा, शोधकर्ताहरूले मिल्की वेमा सुपरनोभा कोर पतन हुने दर प्रति शताब्दी 1.63 ± 0.46 घटनाहरू हुने अनुमान गरेका छन्। त्यसैले, अन्तिम सुपरनोभा घटनालाई हेर्दा, SN 1987A 35 वर्ष पहिले 1987 मा अवलोकन गरिएको थियो, मिल्की वेमा अर्को सुपरनोभा घटना निकट भविष्यमा कुनै पनि समयमा अपेक्षित हुन सक्छ।
Life course of a तारा & supernova
अर्बौं वर्षको टाइम स्केलमा, तारा undergo a life course, they are born, age and finally die with explosion and subsequent dispersal of star materials into interstellar ठाउँ as dust or cloud.
को जीवन तारा 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 तारा determines its lifetime as well as what happens to the star during its life.
सबै तारा 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 कालो प्वाल.
SN 1987A, अन्तिम सुपरनोभा
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 आकाशगंगा 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.
सुपरनोभाको अध्ययन महत्त्वपूर्ण छ
Study of supernova is helpful in several ways such as measuring distances in ठाउँ, understanding of expanding ब्रह्माण्डको and the nature of stars as the factories of all the elements that make everything (including us) found in the ब्रह्माण्डको. 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 ठाउँ during supernova explosion. The supernovas play a key role in distributing elements throughout the ब्रह्माण्डको.
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 आकाशगंगा 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?
न्युट्रिनो, सुपरनोवा विस्फोटको बिकन
जीवनको अन्त्यमा, ताराले यसलाई शक्ति प्रदान गर्ने आणविक फ्युजनको लागि इन्धनको रूपमा हल्का तत्वहरू बाहिर निस्कने क्रममा, भित्री गुरुत्वाकर्षण धक्का हावी हुन्छ र ताराको बाहिरी तहहरू भित्र झर्न थाल्छ। कोर ढल्न थाल्छ र केही मिलिसेकेन्डमा कोर यति संकुचित हुन्छ कि इलेक्ट्रोन र प्रोटोनहरू मिलाएर न्यूट्रोन बनाउँछन् र प्रत्येक न्यूट्रोनको लागि एक न्यूट्रिनो रिलिज हुन्छ।
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 कालो प्वाल depending on the mass of the star) behind and rest of the mass of the star disperses into interstellar ठाउँ.
को ठूलो विस्फोट neutrinos produced as a result of gravitational core-collapse escape into outer ठाउँ 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.
एस्केपिङ न्युट्रिनोले विस्फोटक तारा भित्र चरम घटनाहरूको लागि एक अद्वितीय विन्डो पनि प्रदान गर्दछ जसको आधारभूत बलहरू र प्राथमिक कणहरूको बुझाइमा प्रभाव हुन सक्छ।
सुपरनोभा प्रारम्भिक चेतावनी प्रणाली (SNEW)
पछिल्लो पटक अवलोकन गरिएको कोर-कोलेप्स सुपरनोभा (SN1987A) को समयमा, घटनालाई नाङ्गो आँखाले अवलोकन गरिएको थियो। न्यूट्रिनोहरू दुईवटा वाटर चेरेनकोभ डिटेक्टरहरू, कामियोकान्डे-II र इर्भिन-मिशिगन ब्रूखाभेन (आईएमबी) प्रयोगद्वारा पत्ता लगाइएको थियो जसले 19 न्यूट्रिनो अन्तरक्रिया घटनाहरू अवलोकन गरेको थियो। यद्यपि, न्युट्रिनोको पहिचानले सुपरनोभाको अप्टिकल अवलोकनमा बाधा पुर्याउन बिकन वा अलार्मको रूपमा काम गर्न सक्छ। नतिजाको रूपमा, विभिन्न वेधशालाहरू र खगोलविद्हरूले अध्ययन गर्न र डेटा सङ्कलन गर्न समयमै कार्य गर्न सकेनन्।
1987 देखि, न्यूट्रिनो खगोल विज्ञान धेरै उन्नत छ। अब, सुपरनोभा सतर्कता प्रणाली SNWatch स्थानमा छ जुन सम्भावित सुपरनोभा अवलोकनको बारेमा विशेषज्ञहरू र सम्बन्धित संस्थाहरूलाई अलार्म बजाउन प्रोग्राम गरिएको छ। र, विश्वभरि न्युट्रिनो पर्यवेक्षकहरूको नेटवर्क छ, जसलाई सुपरनोभा अर्ली वार्निङ सिस्टम (SNEWS) भनिन्छ जसले पत्ता लगाउने विश्वासमा सुधार गर्न संकेतहरू जोड्दछ। कुनै पनि सामान्य गतिविधि व्यक्तिगत डिटेक्टरहरू द्वारा केन्द्रीय SNEWS सर्भरमा सूचित गरिन्छ। यसबाहेक, SNEWS ले हालसालै SNEWS 2.0 मा अपग्रेड गरेको थियो जसले कम-विश्वास अलर्टहरू पनि उत्पादन गर्दछ।
मिल्कीवेमा आसन्न सुपरनोभा
Neutrino observatories spread across the world are aiming at first detection of neutrinos resulting from gravitational core collapse of the stars in our home आकाशगंगा. Their success therefore, is very much dependent on the rate of supernova core collapse in the Milky Way.
भर्खरै प्रकाशित कागजातहरूमा, शोधकर्ताहरूले मिल्की वेमा सुपरनोभा कोर पतन हुने दर प्रति १०० वर्षमा १.६३ ± ०.४६ घटना हुने अनुमान गरेका छन्; प्रति शताब्दी लगभग एक देखि दुई सुपरनोभा। यसबाहेक, अनुमानहरूले मिल्की वेमा कोर कोलेप्स सुपरनोभा बीचको समय अन्तराल ४७ देखि ८५ वर्षको बीचमा हुनसक्छ भनी सुझाव दिन्छ।
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 ब्रह्माण्डको.
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स्रोत:
- आतिशबाजी ग्यालेक्सी, NGC 6946: What Make this ग्यालेक्सी 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. सुपरनोभा न्यूट्रिनो डिटेक्शन। प्रिप्रिन्ट axRiv। मा उपलब्ध छ https://arxiv.org/pdf/1205.6003.pdf
- खरुसी एस अल, एट अल 2021. SNEWS 2.0: बहु-मेसेन्जर खगोल विज्ञानको लागि अर्को पुस्ताको सुपरनोभा प्रारम्भिक चेतावनी प्रणाली। भौतिक विज्ञानको नयाँ जर्नल, भोल्युम 23, मार्च 2021। 031201। DOI: https://doi.org/10.1088/1367-2630/abde33
- Rozwadowskaab K., Vissaniab F., and Cappellaroc E., 2021. on the core collapse supernovae in the Milky way. नयाँ खगोल विज्ञान खण्ड 83, फेब्रुअरी 2021, 101498। DOI: https://doi.org/10.1016/j.newast.2020.101498. प्रिप्रिन्ट axRiv मा उपलब्ध छ https://arxiv.org/pdf/2009.03438.pdf
- मर्फे, CT, एट अल 2021. साक्षी इतिहास: आकाश वितरण, पत्ता लगाउने योग्यता, र नग्न आँखा मिल्की वे सुपरनोभाको दर। रोयल एस्ट्रोनोमिकल सोसाइटीको मासिक सूचनाहरू, खण्ड 507, अंक 1, अक्टोबर 2021, पृष्ठ 927-943, DOI: https://doi.org/10.1093/mnras/stab2182। प्रिप्रिन्ट axRiv मा उपलब्ध छ https://arxiv.org/pdf/2012.06552.pdf
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