Free Astronomy Magazine November-December 2023 ARABIC VERSION

from the smaller galaxy’s disk. Those stars began to gradually mix with the larger galaxy’s outer halo, forming concentric bands, or shells. A simple anal- ogy is adding a drop of food color to a bowl of bat- ter that you’re slowly stirring. The drop gets stretched out in a spiral that remains visible for a long time before completely mixing. The shells of NGC 3923 make the galaxy quite excep- tional. Not only does it have the largest known shell of all observed shell galaxies, but it also has the [DESI Legacy Im- aging Surveys/LBNL/DOE & KPNO/CTIO/NOIRLab/NSF/ AURA. Image pr ocessing: T.A. Rector (U niversity of Alaska Anchorage/NSF’s NOIRLab),M. Zamani, R. Colom- bari & D. deM artin (NSF’s NOIRLab)] ﻣﻦ ﻗﺮص ا ﺠﺮة اﻷﺻﻐﺮ ﺑﺪأ . ت ﺗﻠﻚ اﻟﻨﺠﻮم ﰲ اﻻﺧﺘﻼط ﺗﺪرﻳﺠﻴ ﺎً ﻣﻊ اﻟ ﻬﺎﻟﺔ اﻟﺨﺎرﺟﻴﺔ ﻟﻠﻤﺠﺮة اﻷﻛﱪ ﺣﺠﻤ ﺎً ﻟﺘﺸﻜﻞ ﻧﻄﺎﻗـﺎت أو أﻏﻠﻔﺔ ﻣﺘﺤﺪة ا ﺮﻛﺰ . ﺗﺸﺒﻴﻪ ﺑﺴﻴﻂ ﻫﻮ إﺿﺎﻓﺔ ﻗﻄﺮة ﻣﻦ ﻟـﻮن اﻟﻄﻌﺎم إﱃ وﻋﺎء ﻣﻦ اﻟﺨﻠﻴﻂ اﻟﺬي ﺗﻘﻮم ﺑﺘﺤﺮﻳﻜﻪ ﺑـﺒﻂء . ًﻳـﺘﻢ ﺗﻤﺪﻳﺪ اﻟﻘﻄﺮة ﰲ ﺷﻜﻞ ﺣﻠﺰوﻧﻲ ﻳﻈﻞ ﻣﺮﺋﻴ ﺎ ﻟﻔﱰة ﻃﻮﻳﻠﺔ ﻗﺒﻞ أن ﻳﻤﺘﺰج ﺗﻤﺎﻣًﺎ . إن أﻏﻠﻔﺔ NGC 3923 ﺗﺠﻌﻞ ا ﺠـﺮة اﺳـﺘﺜﻨﺎﺋﻴﺔ ﺗﻤﺎﻣﺎ ﻟﻴﺲ ﻓﻘﻂ ﻷ ﻧﻬﺎ ﺗﻤﺘﻠﻚ أﻛﱪ ﻗﴩة ﻣﻌﺮوﻓﺔ ﻣﻦ ﺑ ﺟﻤﻴﻊ ا ﺠﺮات اﻟﺼﺪﻓﻴﺔ ا ﺮﺻﻮدة وﻟﻜﻨﻬﺎ ﺗﻤﺘﻠﻚ أﻳﻀﺎً ﺗﻌـﺮض ـﺎﻟﻤﺠﺮات اﻟـ ـﺔ ﻣﻘﺘﻄﻔـﺎتﻣـﻦ اﻟﺼـﻮرة اﻟﻐﻨ NGC 3923 ــــﺎﻣ ا اﻟﻄﺎﻗــــﺔ اﻟﻤﻈﻠﻤــــﺔ اﻟﺘﻘﻄﺘﻬــــﺎ اﻟــــ ) ــــﺎم د ( اﻟﺘﺎ ﻌــــﺔ ﻟــــﻮزارة ــﺎﻟﻎ ــﻮ اﻟ ــﺔ واﻟﻤﺜ ﺘــﺔ ﻋﻠــﻰﺗﻠﺴـ ﻮبﻓ ﻜﺘــﻮرإم ﻼﻧ اﻟﻄﺎﻗــﺔ اﻷﻣﺮ ﻜ 4 أﻣﺘﺎر اﻟﺘﺎﺑﻊ ﻟﻤﺆﺳﺴﺔ اﻟﻌﻠﻮم اﻟﻮﻃﻨ ﺔ ﻤﺮﺻﺪﺳـ و ﺗ ﻮﻟﻮﻟـﻮ ﺘﺸـ ﻠﻲ وﻫﻮ ﺑﺮ ﺎﻣﺞ ﻟﻤﺨﺘ ﻧﻮﻳﺮﻻب اﻟﺘﺎﺑﻊ ﻟﻤﺆﺳﺴﺔ اﻟﻌﻠﻮم اﻟﻮﻃﻨ ﺔ . [DESI LegacyIm-aging Surveys/LBNL/DOE&KPNO/CTIO/NOIRLab/NSF/ AURA.Image processing:T.A.Rector (UniversityofAlaska Anchorage/NSF’sNOIRLab),M. Zamani, R.Colom-bari &D.de Martin (NSF’sNOIRLab)] ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 25 ﻧﻮﻓﻤﺒﺮ - ﺩﻳﺴﻤﺒﺮ 2 0 2 3