Free Astronomy Magazine July-August 2023 ARABIC VERSION

which are present in the outer layers of stars. But some of these explo- sions were not energetic enough to expel heavier elements like iron, which is found only in the cores of stars. To search for the telltale sign of these very first stars that ex- ploded as low energy supernovae, the team therefore looked for dis- tant gas clouds poor in iron but rich in the other elements. And they found just that: three faraway clouds in the early Universe with very little iron but plenty of carbon and other elements — the finger- print of the explosions of the very first stars. This peculiar chemical composition has also been observed in many old stars in our own gal- axy, which researchers consider to be second- generation stars that formed directly from the ‘ashes’ of the first ones. This new study has found such ashes in the early Universe, thus adding a missing piece to this puz- zle. “Our discovery opens new avenues to indi- rectly study the nature of the first stars, fully com- stars in our galaxy,” explains Salva- dori. To detect and study these distant gas clouds, the team used light bea- cons known as quasars — very bright sources powered by supermassive black holes at the centres of far- away galaxies. As the light from a quasar travels through the Universe, it passes through gas clouds where different chemical elements leave an imprint on the light. To find these chemical imprints, the team analysed data on several quasars observed with the X-shooter instrument on ESO’s VLT. X-shooter splits light into an extremely wide range of wavelengths, or colours, which makes it a unique instrument with which to identify many differ- ent chemical elements in these dis- tant clouds. This study opens new windows for next generation telescopes and in- struments, like ESO’s up- coming Extremely Large Telescope (ELT) and its high-resolution Arma- zoNes high Dispersion Echelle Spectrograph (ANDES). “With ANDES at the ELT we will be able to study many of these rare gas clouds in greater detail, and we will be able to finally uncover the mysterious nature of the first stars,” concludes Valentina D’Odorico, a researcher at the National Institute of Astrophysics in Italy and co-author of the plementing studies of study.    ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 34 ا ﺸــﺎرﻛﺔ ﰲ ﺟﺎﻣﻌــﺔ ﻓﻠﻮرﻧﺴــﺎ وا ﺆﻟﻔــﺔ ا ﺸﺎرﻛﺔ ﻟﻠﺪراﺳﺔ ا ﻨﺸﻮرة ﰲ ﻣﺠﻠﺔ اﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴﺔ " : ﻳﻤﻜـﻦ دراﺳـﺔ اﻟﻨﺠـﻮم اﻟﺒﺪاﺋﻴـﺔ ﺑﺸﻜﻞ ﻏـ ﻣﺒـﺎﴍ ﻋـﻦ ﻃﺮﻳـﻖ اﻛﺘﺸـﺎف اﻟﻌﻨﺎﴏ اﻟﻜﻴﻤﻴﺎﺋﻴﺔ اﻟﺘﻲ ﻧـﴩﺗﻬﺎ ﺎ ﰲ ﺑﻴﺌﺘﻬـ ﺑﻌﺪ ﻣﻮﺗﻬ . ﺎ ﺑﺎﺳﺘﺨﺪام اﻟﺒﻴﺎﻧﺎت ا ﺄﺧﻮذة ﻣﻦ اﻟﺘﻠﺴﻜﻮب اﻟﻜﺒ ﺟﺪا ﰲ ﺗﺸﻴﲇ وﺟﺪ اﻟﻔ ﺮﻳﻖ ﺛﻼث ﻏﻴﻮم ﻏﺎزﻳﺔ ﺑﻌﻴﺪة ﺟﺪًا ﺷﻮﻫﺪت ﻋﻨﺪﻣﺎ ﻛﺎن ا ﻟﻜﻮن 10 - 15 ٪ ﻓﻘﻂ ﻣﻦ ﻋﻤﺮه اﻟﺤﺎﱄ وﺑﺼﻤﺔ ﻛﻴﻤﻴﺎﺋﻴﺔ ﺗﻄـﺎﺑﻖ ﻣـﺎ ﻧﺘﻮﻗﻌـﻪ ﻣـﻦ اﻧﻔﺠﺎرات اﻟﻨﺠﻮم اﻷوﱃ . اﻋﺘﻤﺎدًا ﻋـﲆ ﻛﺘﻠـﺔ ﻫـﺬه ا ﻟﻨﺠـﻮم ا ﺒﻜـﺮة وﻃﺎﻗـﺔ اﻧﻔﺠﺎراﺗﻬـﺎ أﻃﻠﻘ ـﺖ ﻫ ـﺬه ا ﺴ ـﺘﻌﺮات اﻟﻌﻈﻤ ـﻰ اﻷوﱃ ﻋﻨﺎﴏ ﻛﻴﻤﻴﺎﺋﻴـﺔ ﻣﺨﺘﻠﻔـﺔ ﻣﺜـﻞ اﻟﻜﺮﺑـﻮن واﻷﻛﺴــﺠ وا ﻐﻨﻴﺴ ــﻴﻮم ا ﻮ ﺟ ــﻮدة ﰲ اﻟﻄﺒﻘﺎت اﻟﺨﺎرﺟ ﻴﺔ ﻟﻠﻨﺠﻮم ﻟﻜﻦ ﺑﻌﺾ ﻫـﺬه اﻻﻧﻔﺠﺎرات ﻟﻢ ﺗﻜﻦ ﻧﺸﻄﺔ ﺑﻤﺎ ﻳﻜﻔﻲ ﻟﻄـﺮد اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ ﻣﺜـﻞ اﻟﺤﺪﻳـﺪ اﻟـﺬي ﻳﻮﺟـﺪ ﻓﻘﻂ ﰲ ﻗﻠﺐ اﻟﻨﺠﻮم . ﻟﻠﺒﺤـﺚ ﻋـﻦ اﻟﻌﻼﻣـﺔ اﻟﻮاﺿﺤﺔ ﻟﻬﺬه اﻟﻨﺠﻮم اﻷوﱃ اﻟﺘـﻲ اﻧﻔﺠـﺮت ﻋـﲆ ﺷـﻜﻞ ﻣﺴـﺘﻌﺮات ﻋﻈﻤـﻰ ﺔ ﻣﻨﺨﻔﻀـ اﻟﻄﺎﻗﺔ ، ﺑﺤﺚ اﻟﻔﺮﻳﻖ ﻋﻦ ﻏﻴﻮم ﻏﺎزﻳﺔ ﺑﻌﻴﺪة ﻓﻘ ـ ة ﺑﺎﻟﺤﺪﻳ ـﺪ ﻟﻜﻨﻬ ـ ﺎ ﻏﻨﻴ ـﺔ ﺑﺎﻟﻌﻨ ـﺎﴏ اﻷﺧﺮى . ووﺟﺪوا ذﻟﻚ ﺑﺎﻟﻀﺒﻂ : ﺛﻼث ﻏﻴـﻮم ـــ ﺑ ﻌﻴﺪة ﰲ ﺑﺪاﻳﺎت اﻟﻜﻮن ﺗﺤﺘﻮي ﻋﲆ اﻟﻘﻠﻴﻞ ﺟـﺪًا ﻣـﻦ اﻟﺤﺪﻳـﺪ وﻟﻜـﻦ اﻟﻜﺜــ ﻣـﻦ اﻟﻜﺮﺑـﻮن وﻋﻨ ــﺎﴏ أﺧــﺮى ﺑﺼــﻤﺔ اﻧﻔﺠﺎرات اﻟﻨﺠﻮم اﻷوﱃ . ﻟﻘـﺪ ﻟﻮﺣﻆ ﻫﺬا اﻟﱰﻛﻴﺐ اﻟﻜﻴﻤﻴﺎﺋﻲ اﻟﻐﺮﻳﺐ أﻳﻀًـﺎ ﰲ اﻟﻌﺪﻳـﺪ ﻣـﻦ اﻟﻨﺠﻮم اﻟﻘﺪﻳﻤـﺔ ﰲ ﻣﺠﺮ ﺗﻨـﺎ ، واﻟﺘﻲ ﻳﻌﺘﱪﻫﺎ اﻟﺒﺎﺣﺜﻮن ﻣـﻦ ﻧﺠـﻮم اﻟﺠﻴ ـﻞ اﻟﺜ ـﺎﻧﻲ اﻟﺘ ـﻲ ﺗﺸﻜﻠﺖ ﻣﺒﺎﴍة ﻣﻦ " رﻣـﺎد " اﻟﻨﺠـﻮم اﻷوﱃ . وﺟــﺪت ﻫـﺬه اﻟﺪراﺳﺔ اﻟﺠﺪﻳـﺪة ﻣﺜـﻞ ﻫـﺬا اﻟﺮﻣــﺎد ﰲ ﺑــﺪاﻳﺎت اﻟﻜــﻮن وﺑﺎﻟﺘــﺎﱄ أﺿــﺎﻓﺖ ﻗﻄﻌــﺔ ﻣﻔﻘﻮدة إﱃ ﻫﺬا اﻟﻠﻐﺰ . ﻣ ﻔﻘﻮدة إﱃ ﻫﺬا اﻟﻠﻐﺰ . ﻳﻮﺿـﺢ ﺳـﻠﻔﺎدوري : " ﻳﻔـﺘﺢ اﻛﺘﺸـﺎﻓﻨﺎ ﻃﺮﻗًـﺎ ﺟﺪﻳـﺪة ﻟﺪراﺳـﺔ ﻃﺒﻴﻌﺔ اﻟﻨﺠـﻮم اﻷوﱃ ﺑﺸـﻜﻞ ﻏـ ﻣﺒـﺎﴍ ﻣﻜﻤﻼً ﺗﻤﺎﻣًﺎ دراﺳﺎت اﻟﻨﺠـﻮم ﰲ ﻣﺠﺮﺗﻨـﺎ ." ﻻﻛﺘﺸﺎف ودراﺳـﺔ ﻫـﺬه اﻟﺴـﺤﺐ اﻟﻐﺎزﻳـﺔ اﻟﺒﻌﻴﺪة ، اﺳﺘﺨﺪم اﻟﻔﺮﻳـﻖ ﻣﻨـﺎرات اﻟﻀـﻮء ا ﻌﺮوﻓﺔ ﺑﺎﺳـﻢ اﻟﻜـﻮازارات وﻫـﻲ ﻣﺼـﺎدر ﺳﺎﻃﻌﺔ ﻟﻠﻐﺎﻳﺔ ﻣﺪﻋﻮﻣﺔ ﺑـﺎﻟﺜﻘﻮب اﻟﺴـﻮداء ﻓﺎﺋﻘﺔ اﻟﻜﺘﻠﺔ ﰲ ﻣﺮاﻛﺰ ا ﺠﺮات اﻟﺒﻌﻴﺪة . ﻋﻨﺪﻣﺎ ﻳﻨﺘﻘﻞ اﻟﻀـﻮء ﻣـﻦ اﻟﻜـﻮازار ات ﻋـﱪ اﻟﻜﻮن ﻓﺈﻧﻪ ﻳﻤﺮ ﻋﱪ اﻟﺴﺤﺐ اﻟﻐﺎزﻳﺔ ﺣﻴـﺚ ﺗﱰك اﻟﻌﻨﺎﴏ اﻟﻜﻴﻤﻴﺎﺋﻴـﺔ ا ﺨﺘﻠﻔـﺔ ﺑﺼـﻤﺔ ﻋﲆ اﻟﻀـﻮء . ﻟﻠﻌﺜـﻮر ﻋـﲆ ﻫـﺬه اﻟﺒﺼـﻤﺎت اﻟﻜﻴﻤﻴﺎﺋ ﻴﺔ ﻗـﺎم اﻟﻔﺮﻳـﻖ ﺑﺘﺤﻠﻴـﻞ اﻟﺒﻴﺎﻧـﺎت اﻟﺨﺎﺻﺔ ﺑﺎﻟﻌﺪﻳﺪ ﻣﻦ اﻟﻜﻮازارات اﻟﺘﻲ رﺻﺪت ﺑﺎﺳﺘﺨﺪام أداة X-shooter ﻋـﲆ اﻟﺘﻠﺴـﻜﻮب اﻟﻜﺒ ﺟﺪاً ﺣﻴـﺚ ﻳﻘﺴـﻢ اﻟﻀـﻮء إﱃ ﻧﻄـﺎق واﺳﻊ ﻟﻠﻐﺎﻳﺔ ﻣﻦ اﻷﻃﻮال ا ﻮﺟﻴﺔ أو اﻷﻟـﻮان ﻣﻤﺎ ﻳﺠﻌﻠﻪ أداة ﻓﺮﻳﺪة ﻳﻤﻜـﻦ ﻦ ﺧﻼﻟﻪ ﻣ ﺗﺤﺪﻳﺪ ﻋﺪة ﻋﻨﺎﴏ ﻛﻴﻤﻴﺎﺋ ﻴــﺔ ﰲ ﻫــﺬه اﻟﻐﻴــﻮم اﻟﺒﻌﻴﺪ . ة ﺗﻔﺘﺢ ﻫـﺬه اﻟﺪراﺳـﺔ ﻧﻮاﻓﺬ ﺟﺪﻳﺪة ﻷﺟﻬـﺰة اﻟﺠﻴـﻞ اﻟﺘﺎﱄ ﻣﺜﻞ اﻟﺘﻠﺴـﻜﻮب اﻟﻜﺒـ ﻟﻠﻐﺎﻳــﺔ وﻣﻄﻴﺎﻓــﺔ اﻧــﺪﻳﺲ ارﻣﺎزون ﻋﺎﱄ اﻟﺘﺸﺘﺖ . ﺗﺨﺘ ـﺘﻢ ﻓﺎﻟﻨﺘﻴﻨــﺎ دودورﻳﻜ ـﻮ اﻟﺒﺎﺣﺜــﺔ ﺑﺎ ﻌﻬــﺪ اﻟــﻮﻃﻨﻲ ﻟ ﻠﻔﻴﺰﻳـﺎء اﻟﻔﻠﻜﻴ ـﺔ ﺑ ﺈﻳﻄﺎﻟﻴ ـﺎ او ا ﺆﻟﻒ :" ﺸـﺎرك ﺳـﻨﺘﻤﻜﻦ ﻣــ ﻦ دراﺳـﺔ اﻟﻐﻴـﻮ م ﻏﺎزﻳـﺔ ﺎﻟﺑ ﺘﻔﺼـﻴﻞ ﻌﺮﻓـﺔ اﻟﻄﺒﻴﻌـﺔ اﻟﻐﺎﻣﻀﺔ ﻟﻠﻨﺠﻮم اﻷوﱃ . ، ﺎﺳﺘﺨﺪام اﻟ ﺘﻠﺴ ﻮب اﻟ ﻜﺒـ ﺟـﺪًا اﻟﺘـﺎﺑﻊ ﻟﻠﻤﺮﺻـﺪ اﻷوروﺑـﻲ اﻟــﺠﻨﻮﺑﻲ وﺟـﺪ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ اﻟ ﺼـﻤﺎت اﻟـ ﺧﻠﻔﺘﻬﺎ اﻧﻔﺠﺎرات اﻟﻨﺠﻮم اﻷوﻟﻰ . ﻫﺬا اﻟﻔ ﺪﻳﻮ ﻠﺨﺺاﻻﻛﺘﺸﺎف . [ESO] ُﻈﻬﺮ ﻫﺬا اﻟﺮﺳﻢ اﻟﺘﺨ ﻠﻲ ﺳﺤﺎ ﺔ ﻏﺎ ـﺔ ﻣﺨﺘﻠﻔـﺔ ز ﻌ ﺪة ﺗﺤﺘـﻮيﻋﻠـﻰﻋﻨﺎﺻـﺮﻛ ﻤ ﺎﺋ ﻣﻮﺿﺤﺔ ﻫﻨﺎ ﺘﻤﺜﻴﻞ ﺗﺨﻄ ﻄ ﻲ ﻟﺬرات ﻣﺨﺘﻠﻔﺔ . ] ESO/L. Calçada, M. Kornmesser [ ﻳﻮﻟﻴﻮ - ﺃﻏﺴﻄﺲ 2 0 2 3