Free Astronomy Magazine November-December 2022 ARABIC VERSION

ASTRO PUBLISHING 17 Deducing the quantities of each el- ement present, however, is a tricky endeavor because the brightness of a line in a spectrum depends on many other factors besides the ele- ment’s abundance. Two co-authors of the analysis, Yuzuru Yoshii and Hi- roaki Sameshima of the University of Tokyo, have tackled this problem by developing a method of using the in- tensity of wavelengths in a quasar spectrum to estimate the abundance of the elements present there. It was by using this method to analyze the quasar’s spectrum that they and their colleagues discovered the conspicu- ously low magnesium-to-iron ratio. “It was obvious to me that the super- nova candidate for this would be a pair-instability supernova of a Popu- lation III star, in which the entire star his artist’s impression shows a Population III star that is 300 times more massive than our Sun exploding as a pair-in- stability supernova — an all- consuming version of a supernova that has yet to be di- rectly observed. New research may have detected the after- math of one, however, in the clouds surrounding one of the most-distant quasars ever detected. [NOIRLab/NSF/AURA/ J. da Silva/Spaceengine] explodes without leaving any rem- nant behind,” said Yoshii. “I was de- lighted and somewhat surprised to find that a pair-instability supernova of a star with a mass about 300 times that of the Sun provides a ratio of magnesium to iron that agrees with the low value we derived for the quasar.” Searches for chemical evidence for a previous generation of high-mass Population III stars have been carried out before among the stars in the halo of the Milky Way and at least one tentative identification was pre- sented in 2014. Yoshii and his col- leagues, however, think the new result provides the clearest signature of a pair-instability supernova based on the extremely low magnesium-to- iron abundance ratio presented in this quasar. If this is indeed evidence of one of the first stars and of the remains of a pair-instability supernova, this discov- ery will help to fill in our picture of how the matter in the Universe came to evolve into what it is today, includ- ing us. To test this interpretation more thoroughly, many more obser- vations are required to see if other objects have similar characteristics. But we may be able to find the chem- ical signatures closer to home, too. Although high-mass Population III stars would all have died out long ago, the chemical fingerprints they leave behind in their ejected material can last much longer and may still linger on today. This means that as- tronomers might be able to find the signatures of pair-instability super- nova explosions of long-gone stars still imprinted on objects in our local Universe. “We now know what to look for; we have a pathway,” said co-author Timothy Beers, an as- tronomer at the University of Notre Dame. “If this happened locally in the very early Universe, which it should have done, then we would expect to find evidence for it.”    NOVEMBER-DECEMBER 2022 T إن ﻣﻌﺮﻓﺔ ﻛﻤﻴﺎ ﻣﻬﻤﺔ ت ﻛﻞ ﺷﺪة ﺻﻌﺒﺔ ﻷن ﺳﻄﻮع ﺧﻂ ﰲ اﻟﺘﺤﻠﻴﻞ اﻟﻄﻴﻔﻲ ﺗ ﻌﺘﻤﺪ ﻋـﲆ اﻟﻌﺪﻳﺪ ﻣﻦ اﻟﻌﻮاﻣﻞ اﻷﺧﺮى إﱃ ﺟﺎﻧـﺐ وﻓـﺮة اﻟﻌﻨﴫ . ﻋﺎﻟﺞ اﺛﻨﺎن ﻣﻦ ا ﺆﻟﻔ ا ﺸـﺎرﻛ ﰲ اﻟﺘﺤﻠﻴﻞ ، وﻫﻤﺎ اﻟﺒﺎﺣﺜﺎن ) ﻳﻮزورو ( ﻳﴚ )و ﻫـﻲ روﻛـﻲ ( ﺳﻤﺸـﻴﻤﺎ ﻣـﻦ ﺟﺎﻣﻌـﺔ ﻃﻮﻛﻴﻮ ، ﻫﺬه ا ﺸـﻜﻠﺔ ﻣـﻦ ﺧـﻼل ﺗﻄـﻮﻳﺮ ﻃﺮﻳﻘﺔ ﻻﺳﺘﺨ ﺪام ﻛﺜﺎﻓﺔ اﻷﻃﻮال ا ﻮﺟﻴـﺔ ﰲ ﻃﻴ ـﻒ اﻟﻜــﻮازار ﻟﺘﻘ ـﺪﻳﺮ وﻓــﺮة اﻟﻌﻨــﺎﴏ ا ﻮﺟﻮدة ﻫﻨﺎك . ﺑﺎﺳـﺘﺨﺪام ﻫـﺬه اﻟﻄﺮﻳﻘـﺔ ﻟﺘﺤﻠﻴ ـﻞ ﻃﻴ ـﻒ اﻟﻜـﻮازار ، اﻛﺘﺸ ـﻔﻮا ﻫ ـﻢ وزﻣﻼؤﻫـﻢ ﻧﺴـﺒﺔ ا ﻐﻨﻴﺴــﻴﻮم إﱃ اﻟﺤﺪﻳــﺪ ا ﻨﺨﻔﻀﺔ ﺑﺸـﻜﻞ واﺿـﺢ " . ﻛـﺎن واﺿـﺤًﺎ ﺑﺎﻟﻨﺴﺒﺔ ﱄ أن ا ﺴﺘﻌﺮ اﻷﻋﻈﻢ ا ﺮﺷﺢ ﻟﻬـﺬا ﺳﻴﻜﻮن ﻣﺴﺘﻌﺮ أﻋﻈﻢ ﺛﻨﺎﺋﻲ ﻋﺪم اﻻﺳﺘﻘﺮار ﻟﻨﺠﻮم اﻟﺠﻤﻬﺮة اﻟﺜﺎﻟﺜﺔ ﻳﻨﻔﺠﺮ ﺣﻴﺚ اﻟـﻨﺠﻢ ﺑﺄﻛﻤﻠــﻪ ﺑــ ﺪون ﺗــﺮك أي ﺑﻘﺎﻳــﺎ وراﺋــﻪ ـــ ـــــــ ﻗﺎل ﻳﻮﳾ " . ﻟﻘﺪ ﻛﻨﺖ ﻣﴪورًا وﻣﺘﻔﺎﺟﺌًﺎ إﱃ ﺣﺪ ﻣﺎ ﻋﻨﺪﻣﺎ اﻛﺘﺸـﻔﺖ أن ﻣﺴـﺘﻌﺮًا أﻋﻈـﻢ ﺛﻨﺎﺋﻲ اﻻﺳـﺘﻘﺮار ﻟـﻨﺠﻢ ﻛﺘﻠﺘـﻪ ﺣـﻮاﱄ ٣٠٠ ﺿـﻌﻒ ﻛﺘﻠـﺔ اﻟﺸـﻤﺲ ﻳـﻮﻓﺮ ﻧﺴـﺒﺔ ﻣـﻦ ا ﻐﻨﻴﺴﻴﻮم إ ﱃ اﻟﺤﺪﻳـﺪ ﺗﺘﻔـﻖ ﻣـﻊ اﻟﻘﻴﻤـﺔ ا ﻨﺨﻔﻀﺔ اﻟﺘﻲ اﺳﺘﻨﺘﺠﺖ ﻟﻠﻜﻮازار ". ﺗﻢ إﺟﺮاء ﻋﻤﻠﻴﺎت اﻟﺒﺤﺚ ﻋﻦ أدﻟﺔ ﻛﻴﻤﻴﺎﺋﻴـﺔ ﻟﺠﻴﻞ ﺳﺎﺑﻖ ﻣﻦ ﻧﺠﻮم اﻟﺠﻤﻬﺮة اﻟﺜﺎﻟﺜﺔ ﻋﺎﻟﻴﺔ اﻟﻜﺘﻠﺔ ﺳﺎﺑﻘﺔ ﺑ اﻟﻨﺠﻮم ا ﻮﺟﻮدة ﰲ ﻫﺎﻟـﺔ درب اﻟﺘﺒﺎﻧﺔ وﺗﻢ ﺗﻘﺪﻳﻢ ﺗﻌﺮﻳﻒ ﻣﺒﺪﺋﻲ ﰲ ﻋﺎم ٢٠١٤ . وﻣﻊ ذﻟﻚ، ﻳﻌﺘﻘﺪ ﻳـﻮﳾ وزﻣـﻼؤه أن اﻟﻨﺘﻴﺠﺔ اﻟﺠﺪﻳﺪة ﺗﻮﻓﺮ أوﺿـﺢ إﺷـﺎرة ﻋـﲆ وﺟﻮد ﻣﺴﺘﻌﺮ أﻋﻈﻢ ﺛﻨﺎﺋﻲ ﻣﻀـﻄﺮب ﺑﻨـﺎءً ﻋـﲆ ﻧﺴـﺒﺔ وﻓـﺮة ا ﻐﻨﻴﺴـﻴﻮم إﱃ اﻟﺤﺪﻳـﺪ ا ﻨﺨﻔﻀﺔ ﻟﻠﻐﺎﻳﺔ ا ﻮﺟﻮدة ﰲ ﻫﺬا اﻟﻜﻮازار . إذا ﻛﺎن ﻫﺬا ﺑﺎﻟﻔﻌﻞ دﻟﻴﻼً ﻋﲆ أﺣـﺪ اﻟﻨﺠـﻮم اﻷوﱃ وﺑﻘﺎﻳﺎ ﻣﺴﺘﻌﺮ أﻋﻈﻢ ﺛﻨﺎﺋﻲ ﻣﻀـﻄﺮب ﻓﺈن ﻫﺬا اﻻﻛﺘﺸﺎف ﺳﻴﺴﺎﻋﺪ ﰲ ﻢﻓﻬ ﻛﻴﻔﻴـﺔ ﺗﻄﻮر ا ﺎدة ﰲ اﻟﻜﻮن إﱃ ﻣﺎ ﻫﻲ ﻋﻠﻴﻪ اﻟﻴﻮم . ﻻﺧﺘﺒﺎر ﻫﺬا اﻟﺘﻔﺴ ﺑﺸﻜﻞ أﻛﺜﺮ ﺷﻤﻮﻻً ﻳﻠﺰم إﺟﺮاء اﻟﻌﺪﻳﺪ ﻣﻦ اﻷرﺻﺎد ﻌﺮﻓـﺔ إذا ﻛﺎﻧـﺖ اﻷﺟﺮام اﻷﺧﺮى ﻟﻬﺎ ﺧﺼﺎﺋﺺ ﻣﻤﺎﺛﻠﺔ . ﻟﻜﻦ ﻗﺪ ﻧﺘﻤﻜﻦ ﻣﻦ اﻟﻌﺜـﻮر ﻋـﲆ اﻟﺒﺼـﻤﺎت اﻟﻜﻴﻤﻴﺎﺋﻴـﺔ اﻷﻗـﺮب إﱃ اﻷرض أﻳﻀًـﺎ . ﻋـﲆ اﻟﺮﻏﻢ ﻣﻦ أن ﻧﺠـﻮ م اﻟﺠﻤﻬـﺮة اﻟﺜﺎﻟﺜـﺔ ذات اﻟﻜﺘﻠﺔ اﻟﻌﺎﻟﻴﺔ ﻟﻴﺲ ﻟﻬـﺎ وﺟـﻮد ﻣﻨـﺬ ﻓـﱰة ﻃﻮﻳﻠـﺔ إﻻ أن اﻟﺒﺼـﻤﺎت اﻟﻜﻴﻤﻴﺎﺋﻴـﺔ اﻟﺘـﻲ ﺗﱰﻛﻬﺎ وراءﻫﺎ ﰲ ا ﻮاد ا ﻘﺬوﻓـﺔ ﻳﻤﻜـﻦ أن ﺗﺴﺘﻤﺮ ﻟﻔﱰة أﻃﻮل ورﺑﻤﺎ ﻻ ﺗﺰال ﺑﺎﻗﻴﺔ ﺣﺘﻰ اﻟﻴﻮم . و ﻫﺬا ﻳﻌﻨﻲ اﻧﻪ ﻗﺪ ﻳﻜﻮن ﺑﻤﻘﺪور اﻟﻌﻠﻤﺎء ﻋﲆ اﻟﻌﺜﻮر ﻋﲆ ﺑﺼﻤﺎت اﻧﻔﺠـﺎرات ا ﺴـ ﺘﻌﺮات اﻟﻌﻈﻤﻰ اﻟﺜﻨﺎﺋﻴﺔ ا ﻀﻄﺮﺑﺔ ﻟﻠﻨﺠﻮم اﻟﻘﺪﻳﻤﺔ اﻟﺘﻲ ﻻ ﺗﺰال ﻣﻄﺒﻮﻋﺔ ﻋﲆ أﺟﺴﺎم ﰲ اﻟﻜـﻮن ا ﺤﲇ . " ﻧﺤﻦ ﻧﻌـﺮف اﻵن ﻣـﺎ اﻟـﺬي ﻧﺒﺤـﺚ ﻋﻨـﻪ ؛ ﺑﺤﺴﺐ اﻟﺒﺎﺣﺚ ا ﺸﺎرك ﺗﻴﻤﻮﺛﻲ ﺑ ز ﻋـﺎﻟﻢ اﻟﻔﻠﻚ ﺑ ﺠﺎﻣﻌﺔ ﻧﻮﺗﺮدام " إذا ﺣﺪث ﻫﺬا ﻣﺤﻠﻴًﺎ ﰲ ﺑﺪاﻳﺔ اﻟﻜﻮن وﻫﻮ ﻣﺎ ﻛـﺎن ﻳﺠـﺐ ﺣﺪوﺛـﻪ ﻓ ﻨﺘﻮﻗﻊ اﻟﻌﺜﻮر ﻋﲆ دﻟﻴﻞ ﻋﲆ ذﻟﻚ ". ُﻈﻬـﺮ ﻫــﺬا اﻟﺮﺳــﻢ اﻟﺘﺨ ﻠـﻲ ــﻢ اﻟــ أن ﻧ ـ ﻤﻬﺮة اﻟﺜﺎﻟﺜــــــﺔ أﻛــــــ ﻤﻘـــــــﺪار ٣٠٠ ﻣــــــﺮة ﻣــــــﻦ اﻟﺸـــــــﻤﺲ وﻫـﻮ ﻨﻔﺠـﺮﻋﻠــﻰﺷـ ﻞ ﻣﺴـﺘﻌﺮأﻋﻈـﻢ ﺛﻨــﺎﺋﻲ ﻣﻀــــﻄﺮ - وﻫــــﻮ ﻧﺴــــﺨﺔ ﻣﺴــــﺘﻬﻠﻜﺔ ﺎﻟ ﺎﻣــــﻞ ــــــﺘﻢ رﺻــــــﺪﻩ ﺸـــــــ ﻞ ﻣــــــﻦ ﻣﺴــــــﺘﻌﺮأﻋﻈــــــﻢ ﻟـــــــﻢ ﻣ ﺎﺷﺮ ﻌﺪ . ــــــﺪ ﻗــــــﺪ اﻛﺘﺸــــــﻒ إﺣـــــــﺪ ــــــﻮن ﺑﺤــــــﺚﺟﺪ ﻗــــــﺪ ﻳ اﻟــــــﺪﻻﺋﻞ ﻓــــــﻲ اﻟ ﺴــــــﺤﺐ اﻟﻤﺤ ﻄــــــﺔ ﺑﻮاﺣــــــﺪ ﻣــــــﻦ ﺗــــــﻢ اﻛﺘﺸــــــﺎﻓﻬﺎ ﻋﻠــــــﻰ ــــــﻮازارات اﻟــــــ أ ﻌــــــﺪ اﻟ اﻹﻃﻼق . ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ١٧ ﻧﻮﻓﻤ دﻳﺴﻤ 2022

RkJQdWJsaXNoZXIy MjYyMDU=