Free Astronomy Magazine September-October 2025 ARABIC VERSION

SEPTEMBER-OCTOBER2025   Webb digs into structural origins of disk galaxies byNASA/ESA/CSA AbigailMajor5HannahBraun resent-day disk galaxies often containathick, star-filled outer disk and an embedded thindiskofstars.For instance, our own Milky Way galaxy’s thick disk is approxi- mately 3,000 light- years in height, and its thin disk is roughly 1,000 light- years thick. How and why does this dual disk struc- ture form? By ana- lyzing archival data frommultipleobser- vational programs by NASA’s James Webb Space Tele- scope,ateamofas- tronomersiscloser to answers, as well as understand- ing the origins of disk galaxies in general.Theteamcarefullyidenti- fied,visuallyverified,andanalyzed a statistical sample of 111 edge-on disk galaxies at various periods — up to 11 billion years ago (or ap- proximately2.8billionyearsafter the big bang). This is the first time scientists have investigated thick- and thin-disk structures spanning such vast distances, bridging the gapbetweenobserversprobingthe earlyuniverseandgalacticarchae- ologists seeking to understand our own galaxy’s history. “This unique measurement of the thickness of the disks at high red- shift, or at times in the early uni- verse,isabenchmarkfortheoretical study that was only possible with Webb,” said Takafumi Tsukui, lead author of the paper and a re- searcherattheAustralianNational ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 28 " و ﺐ" ﺴﺘﻜﺸﻒ أ ﺻﻮل اﻟﻤﺠﺮات اﻟﻘﺮﺻ ﺔ : ﻘﻠﻢ أﺑﻴﺠﻴﻞ ﻣﻴﺠﻮر و ﻫﺎﻧﺎ ﺑﺮاون و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ ـ ﺎً ﻏﺎﻟ ﻣﺎ ﺗﺤﺘﻮي ﻣﺠﺮات اﻟﻘــﺮص اﻟﺤﺎﻟﻴــﺔ ﻋــﲆ ﻗـﺮصﺧـﺎرﺟﻲ ﺳـﻤﻴﻚ ﻣـﲇء ﺑـﺎﻟﻨﺠﻮم وﻗـﺮص رﻗﻴﻖ ﻣﺪﻣﺞ ﻣﻦ اﻟﻨﺠـﻮم . ﻋـﲆ ﺳـﺒﻴﻞ ا ﺜـﺎل ﻳﺒﻠـﻎ ارﺗﻔﺎع اﻟﻘـﺮص اﻟﺴـﻤﻴﻚ ﺠﺮﺗﻨﺎ درب اﻟﺘﺒﺎﻧﺔ ﺣﻮاﱄ 3000 ﺳﻨﺔ ﺿﻮﺋﻴﺔ ﺑﻴﻨﻤﺎ ﻳﺒﻠﻎ ﺳﻤﻚ ﻗﺮﺻﻬﺎ اﻟﺮﻗﻴﻖ ﺣ ـــﻮاﱄ 1000 ﺳــــﻨﺔ . ﺿــﻮﺋﻴﺔ ﻛﻴــﻒ و ــﺎذا ﻳﺘﺸــﻜﻞ ﻫــﺬا اﻟﻬﻴﻜــﻞ اﻟﻘـﺮﴆ ا ـﺰدوج؟ ﻣـﻦ ﺧ ـﻼل ﺗﺤﻠﻴ ـﻞ اﻟﺒﻴﺎﻧ ـﺎت ا ﻷرﺷـﻴﻔﻴﺔ ﻣ ـﻦ ﺑ ـﺮاﻣﺞ رﺻﺪ ﻣﺘﻌـﺪدة ﺑﻮاﺳـﻄﺔ ﺗﻠﺴـﻜﻮ ب ﺟـﻴﻤﺲ وﻳـﺐ اﻟﻔﻀﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟ ﻮﻛﺎﻟـﺔ ﻧﺎﺳﺎ أﺻـﺒﺢ ﻓﺮﻳـﻖ ﻣـﻦ اﻟﻔﻠﻚ أﻗﺮب إﱃ اﻹﺟﺎﺑـﺎت، ﻜﻴ أﻗﺮب إﱃ اﻹﺟﺎﺑﺎت ﻓﻀﻼً ﻋـﻦ ﻓﻬـﻢ أﺻﻮل ﻣﺠﺮات اﻟﻘـﺮص ﺑﺸـﻜﻞ ﻋـﺎم . ﺣـﺪد اﻟﻔﺮﻳﻖ ﺑﻌﻨﺎﻳﺔ وﺗﺤﻘﻖ ﺑ ﴫﻳﺎً ـ وﺣﻠـﻞ ﻋﻴﻨـﺔ إﺣﺼﺎﺋﻴﺔ ﻣﻦ 111 ﻣﺠﺮة ﻗﺮﺻ ﻴﺔ ﻋﲆ اﻟﺤﺎﻓﺔ ﰲ ﻓﱰات ﻣﺨﺘﻠﻔﺔ ﺣﺘﻰ 11 ﻣﻠﻴﺎر ﺳﻨﺔ ﻣﻀﺖ ) أو ﻣـﺎ ﻳﻘـﺮب ﻣــﻦ 2.8 ﻣﻠﻴـﺎر ﺳــﻨﺔ ﺑﻌـﺪ اﻻﻧﻔﺠﺎر اﻟ (. ﻌﻈﻴﻢ ﻫﺬه ﻫﻲ ا ﺮة اﻷوﱃ اﻟﺘـﻲ ﻳﺪرس ﻓﻴﻬﺎ اﻟﻌﻠﻤﺎء ﻫﻴﺎﻛﻞ أﻗﺮاص ﺳـﻤﻴﻜﺔ ﻳﺪرس ﻓﻴﻬﺎ اﻟﻌﻠﻤﺎء ﻫﻴﺎﻛﻞ أﻗﺮاص ﺳـﻤﻴﻜﺔ ور ﻗﻴﻘﺔ ﺗﻤﺘﺪ ﻋﲆ ﻣﺴﺎﻓﺎت ﺷﺎﺳـﻌﺔ ﻛﻬـﺬه ﻣﻤﺎ ﻳ ﺴﻬﻢ ﰲ ﺳـﺪ اﻟﻔﺠـﻮة ﺑـ اﻟﺮاﺻـﺪﻳﻦ اﻟﺬﻳﻦ ﻳﺴﺘﻜﺸﻔﻮن اﻟﻜﻮن ا ﺒﻜﺮ وﻋﻠﻤﺎء اﻵﺛﺎر ا ﺠﺮﻳﺔ اﻟﺴﺎﻋ ﻟﻔﻬﻢ ﺗﺎرﻳﺦ ﻣﺠﺮﺗ .ﺎﻨ ﻗﺎل ﺗ ﺎﻛﺎﻓﻮﻣﻲ ﺗﺴـﻮﻛﻮي ا ﺆﻟـﻒ اﻟﺮﺋﻴـ ﴘ ـ ﻟﻠﺪراﺳﺔ واﻟﺒﺎﺣﺚ ﰲ ا ﻌﻬﺪ اﻟﻮﻃﻨﻲ اﻷﺳﱰاﱄ : ﻫﺬا اﻟﻘﻴﺎس اﻟﻔﺮﻳـﺪ ﻟﺴـﻤﻚ اﻷﻗـﺮاص ﻋﻨـﺪ اﻧﺰﻳﺎح أﺣﻤـﺮ ﻋـﺎلٍ، أو ﰲ ﺑﻌـﺾ اﻷﺣﻴـﺎن ﰲ ﻳ" ﻌﺪ ﻫﺬا اﻟﻘﻴﺎس اﻟﻔﺮﻳﺪ ﻟﺴﻤ ﻚ اﻷﻗﺮاصﻋﻨﺪ اﻧﺰﻳﺎح أﺣﻤـﺮ ﻋـﺎلٍ أو ﰲ ﺑﻌـﺾ اﻷﺣﻴـﺎن ﰲ اﻟﻜﻮن ا ﺒﻜﺮ ﻣﻌﻴﺎر اً ﻟﻠﺪراﺳﺎت اﻟﻨﻈﺮﻳﺔ اﻟﺘﻲ ﻟﻢ ﺗﻜﻦ ﻣﻤﻜﻨﺔ إﻻ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮب وﻳـﺐ ﻋـﺎدةً ﻣــﺎ ﺗﻜـﻮن ﻧﺠـﻮ م اﻷﻗـﺮاص اﻷﻗـﺪم واﻟﺴﻤﻴﻜﺔ ﺧﺎﻓﺘﺔ ﺑﻴﻨﻤﺎ ﺗﺘﺄﻟﻖ ﻧﺠﻮم اﻷﻗﺮاص اﻟﺸﺎﺑﺔ واﻟﺮﻓﻴﻌﺔ ﰲ ا ﺠﺮة ﺑﺄﻛﻤﻠﻬﺎ ." اﻟﻤﺠﺮات ذات اﻟﻘﺮص اﻟﺮﻗﻴﻖ واﻟﺴﻤ ﻚ ﺳﺒﺘﻤﺒﺮ - ﺃﻛﺘﻮﺑﺮ 2 0 2 5