Free Astronomy Magazine November-December 2024 ARABIC VERSION

L 38 Potential missing link to first stars in odd galaxy byNASA/ESA/CSA Leah Ramsay ChristinePulliam ookingdeepintotheearlyuni- verse with NASA’s James Webb SpaceTelescope,astronomers havefoundsomethingunprece- dented: a galaxy with an odd light signature, which they attribute to its gas outshining its stars. Found approximately one billion years af- ter the big bang, galaxy GS-NDG- 9422 (9422) may be a missing-link phaseofgalacticevolutionbetween theuniverse’sfirststarsandfamiliar, well-establishedgalaxies. “Myfirst thought in looking at the galaxy’s spectrum was, ‘that’s weird,’ which isexactlywhattheWebbtelescope wasdesignedtoreveal:totallynew phenomenaintheearlyuniverse that will help us understand how the cosmic story began,” said lead researcherAlexCameronoftheUni- versityofOxford. Cameron reached out to colleague Harley Katz, a theorist, to discuss thestrangedata.Workingtogether, theirteamfoundthatcomputer models of cosmic gas clouds heated by very hot, massive stars, to an ex- tent that the gas shone brighterthan the stars, was nearly a perfect match to Webb’s observations. “It looks like these stars must be much hotter and more massive than what we see in the local universe, which makes sense because theearly universe was a very different environment,” said Katz. In the local universe, typical hot, massive stars have a temperature ranging between 70,000 to 90,000 degrees Fahrenheit (40,000 to 50,000 degrees Celsius). Accordingtotheteam,galaxy9422 has stars hotter than 140,000 de- grees Fahrenheit (80,000 degrees Celsius). The research team suspects that the galaxy is in the midst of a brief phase of intense star formation in- sideacloudofdensegasthatispro- ducing a large number of massive, hotstars.Thegascloudisbeinghit with so many photons of light from thestarsthatitisshiningextremely brightly. In addition to its novelty, nebular gas outshining stars is in- triguing because it is something predicted in the environments of the universe’s first generation of stars,whichastronomersclassifyas Population III stars. ﻧﻮﻓﻤﺒﺮ - ﺩﻳﺴﻤﺒﺮ 2 0 2 4 ﻣﺠﺮة ﻏﺮ ﺔ ﻗﺪ ﺗ ﻮن ـاﻟ ﺤﻠﻘﺔ اﻟﻤﻔﻘﻮدة ﻟﻠﻨﺠﻮم اﻷوﻟﻰ : ﻘﻠﻢ ﻟ ﺎ راﻣﺰي و ﺑﻮﻟ ﺎم ﻛﺮﺴﺘ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ اﻛﺘﺸـﻒ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ ﻧﺎﺳـﺎ ﺎً ﺌﺷـﻴ ﻏـ ﻣﺴـﺒﻮق : ﻣﺠـﺮة ذات ﺑﺼـﻤﺔ ﺿﻮﺋﻴﺔ ﻏﺮﻳﺒﺔ، ﻳﻌﺰوﻧﻬﺎ إﱃ أن ﻏﺎزﻫﺎ ﻳﻔﻮق ﺳﻄﻮع ﻧﺠﻮﻣﻬﺎ . ﻗﺪ ﺗﻜﻮن ا ﺠﺮة GS-NDG-9422 (9422) اﻟﺘﻲ وﺟﺪت ﺑﻌـﺪ ﺣـﻮا ﱄ ﻣﻠﻴـﺎر ﻋـﺎم ﻣـﻦ اﻻﻧﻔﺠﺎر اﻟﻌﻈﻴﻢ ﺑﻤﺜﺎﺑﺔ ﺣﻠﻘﺔ ﻣﻔﻘـﻮدة ﰲ ﺗﻄﻮر ا ﺠﺮة ﺑـ اﻟﻨﺠـﻮم اﻷوﱃ ﰲ اﻟﻜـﻮن وا ﺠﺮات ا ﺄﻟﻮﻓﺔ اﻟﺮاﺳﺨﺔ . ﻗﺎل اﻟﺒﺎﺣﺚ اﻟﺮﺋﻴﴘ أ ﻟﻴﻜﺲ ﻛﺎﻣ ون ﻣـﻦ ﺟﺎﻣﻌﺔ أﻛﺴﻔﻮرد " : ﻛﺎﻧﺖ ﻓﻜﺮﺗﻲ اﻷوﱃ ﻋﻨﺪ اﻟﻨﻈﺮ إﱃ ﻃﻴﻒ ا ﺠﺮة " ﻫﺬا ﻏﺮﻳـﺐ " وﻫـﺬا ﺑﺎﻟﻀﺒﻂ ﻣﺎ ﺻُﻤﻢ ﺗﻠﺴﻜﻮب وﻳـﺐ ﻟﻠﻜﺸـﻒ : ﻋﻨﻪ ﻇﻮاﻫﺮ ﺟﺪﻳﺪة ﺗﻤﺎﻣ ﺎً ﰲ اﻟﻜﻮن ا ﺒﻜـﺮ ﺳﺘﺴﺎﻋﺪﻧﺎ ﻋﲆ ﻓﻬـﻢ ﻛﻴـﻒ ﺑـﺪأت اﻟﻘﺼـﺔ اﻟﻜﻮﻧﻴﺔ ." ﺗﻮاﺻﻞ ﻛﺎﻣ ون ﻣـﻊ زﻣﻴﻠـﻪ ﻫـﺎرﱄ ﻛـﺎﺗﺰ وﻫﻮ واﺿـﻊ ﻧﻈﺮﻳـﺎت ﻨﺎﻗﺸـﺔ اﻟﺒﻴﺎﻧـﺎت اﻟﻐﺮﻳﺒﺔ وﺑﺎﻟﻌﻤـﻞ ﻣﻌـﺎً وﺟـﺪ ﻓـﺮﻳﻘﻬﻢ أن اﻟﻨﻤﺎذج اﻟﺤﺎﺳﻮﺑﻴﺔ ﻟﺴﺤﺐ اﻟﻐـﺎز اﻟﻜﻮﻧﻴـﺔ اﻟﺘﻲ ﺗﺴـﺨﻨﻬﺎ اﻟﻨﺠـﻮم اﻟﻀـﺨﻤﺔ ﺷـﺪﻳﺪة اﻟﺤﺮارة، إﱃ اﻟﺤﺪ اﻟـﺬي ﺟﻌـﻞ اﻟﻐـﺎز أﻛﺜـﺮ 38 ﻗــــﺪ ـــــﻮن ﻣـــــﻦ اﻟﻤﻤﻜـــــﻦ ﻣﻼﺣﻈـــــﺔ اﻟﻤﺠـــــﺮة ﻻ ﻳ GS-NDG-9422 وﻣـــــــﻊ ذﻟـــــــﻚ ـــــــﺪو ﻓـــــــﺈن ﻣـــــــﺎ ﻳ ﻛﻀــــــــ ﺎﺑ ﺔ ﺧﺎﻓﺘــــــــﺔ ﻓــــــــﻲﻫــــــــﺬﻩ اﻟﺼــــــــﻮرة اﻟـــــــــ ــــــــــﺐ ــــــــــﺎﻣ ا ﺗﻠﺴــــــــــ ﻮبﺟــــــــــ ﻤﺲو اﻟﺘﻘﻄﺘﻬــــــــــﺎ اﻟﻔﻀـﺎﺋﻲ ـﺎم ﻧ ) ـﺎﻣ ا اﻷﺷـﻌﺔ ﺗﺤـﺖ ا ﻤــﺮاء ــﺔ اﻟﻘﺮ ( ـــﻮن ﻓــﻲ اﻟﻮاﻗـــﻊ اﻛﺘﺸــﺎﻓ ﻗــﺪ ﻳ ﺎً اً راﺋـــﺪ ـــﺪ ﻟﻔﻬــــﻢ ﻳﻮﺟـــﮫ ﻋﻠﻤـــﺎء اﻟﻔﻠـــﻚ إﻟــــﻰﻣﺴـــﺎرﺟﺪ ﺗﻄﻮر اﻟﻤﺠﺮات ﻓﻲ اﻟ ﻮن اﻟﻤ ﻜﺮ . ] NASA,ESA,CSA, STScI, Alex Cameron (Oxford [( اﻟﺤﺮارة إﱃ اﻟﺤـﺪ اﻟـﺬي ﺟﻌـﻞ اﻟﻐـﺎز أﻛﺜـﺮ ﺎُ ﺳﻄﻮﻋ ﻣﻦ اﻟﻨﺠﻮم ﻛﺎﻧﺖ ﻣﻄﺎﺑﻘـﺔ ﺗﻤﺎﻣـﺎ ﻷ رﺻﺎد ﺗﻠﺴﻜﻮب . ﻳﺐ و وﻗﺎل ﻛﺎﺗﺰ " : ﻳﺒﺪو أن ﻫﺬه اﻟﻨﺠﻮم ﻳﺠـﺐ أن ﺗﻜﻮن أﻛﺜﺮ ﺳﺨﻮﻧﺔ وأﻛﱪ ﺣﺠﻤﺎ ﻣﻤﺎ ﻧـﺮاه ﰲ اﻟﻜﻮن ا ﺤﲇ وﻫﻮ أﻣﺮ ﻣﻨﻄﻘﻲ ﻷن اﻟ ﻜﻮن ا ﺒﻜﺮ ﻛﺎن ﺑﻴﺌﺔ ﻣﺨﺘﻠﻔﺔ ﺗﻤﺎﻣ ".ﺎ ﺗـﱰاوح درﺟـﺔ ﺣـﺮارة اﻟﻨﺠـﻮم اﻟﻀـﺨﻤﺔ اﻟﺴﺎﺧﻨﺔ اﻟﺘﻘﻠﻴﺪﻳـﺔ ﰲ اﻟﻜـﻮن ا ﺤـﲇ ﺑـ 70.000 إﱃ 90,000 درﺟـــﺔ ﻓﻬﺮﻧﻬﺎﻳ ــﺖ ) 40,000 إﱃ 50,000 درﺟﺔ ﻣﺌﻮﻳﺔ .( وﻓﻘﺎ ﻟﻠﻔﺮﻳﻖ اﻟﻌﻠﻤﻲ ﺗﺤﺘﻮي ا ﺠـﺮة 9422 ﻋﲆ ﻧﺠـﻮم أﻛﺜـﺮ ﺳـﺨﻮﻧﺔ ﻣـﻦ 140,000 درﺟﺔ ﻓﻬﺮﻧﻬﺎﻳﺖ ) 80,000 درﺟﺔ ﻣﺌﻮﻳﺔ .( ﻳﺸﺘﺒﻪ ﻓﺮﻳﻖ اﻟﺒﺤـﺚ ﰲ أن ا ﺠـﺮة (9422) ﺗﻤﺮ ﺑﻤﺮﺣﻠﺔ ﻗﺼ ة ﻣـﻦ ﺗﻜـﻮﻳﻦ اﻟﻨﺠـﻮم ا ﻜﺜﻒ داﺧﻞ ﺳـﺤﺎﺑﺔ ﻣـﻦ اﻟﻐـﺎز اﻟﻜﺜﻴـﻒ واﻟﺘﻲ ﺗﻨﺘﺞ ﻋﺪد اً اً ﻛﺒـ ﺟـﺪاُ ﻣـﻦ اﻟﻨﺠـﻮم اﻟﻀﺨﻤﺔ اﻟﺴﺎﺧﻨﺔ . ﺗﺘﻌـﺮض اﻟﺴـﺤﺎﺑﺔ اﻟﻐﺎزﻳـﺔ ﻟﻠﻌﺪﻳـﺪ ﻣــﻦ ﻓﻮﺗﻮﻧﺎت اﻟﻀﻮء ﻣﻦ اﻟﻨﺠﻮم اﻟﺘﻲ ﺗﻠﻤﻊ ﻣـﻦ ﺣﻮﻟﻬﺎ . ﺑﺸﺪة ﺑﺎﻹﺿ ـﺎﻓﺔ إﱃ ﺣﺪاﺛــﺔ ا ﺠــﺮة GS-NDG- 9422 (9422) ﻳﻌﺘﱪ اﻟﻐﺎز اﻟﺴﺪﻳﻤﻲ اﻟﺬي ﻳﺘﻔﻮق ﻋﲆ اﻟﻨﺠﻮم ﻣﻮﺿﻮﻋﺎً اً ﻣﺜ ﻻﻫﺘﻤﺎم اﻟﻌﻠﻤﺎ ء أﻣﺮاً ﻷﻧﻪ ﻣﺘﻮﻗﻌـ ﺎً ﺗﻤﺎﻣـﺎ ﰲ ﺑﻴﺌـﺎت اﻟﺠﻴﻞ اﻷول ﻣـﻦ اﻟﻨﺠـﻮم ﰲ اﻟﻜـﻮن ا ﺒﻜـﺮ واﻟﺘـﻲ ﻳﺼـﻨﻔﻬﺎ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﻋـﲆ أﻧﻬـﺎ ﺟﻤﻬﺮة اﻟ ﻨﺠﻮم اﻟﺜﺎﻟﺜﺔ . ﻧﺤﻦ ﻧﻌﻠﻢ أن ﻫﺬه ا ﺠـﺮة ﻻ ﺗﺤﺘـﻮي ﻋـﲆ