Free Astronomy Magazine September-October 2025 ARABIC VERSION

SEPTEMBER-OCTOBER2025 region, researchers have more com- pletely mapped the colliding galaxy clusters’ contents. “With Webb’s observations, we carefully measured the mass of the Bullet Cluster with the largest lens- ing dataset to date, from the galaxy clusters’ cores all the way out to their outskirts,” said Sangjun Cha, the lead author of the paper pub- lished in The Astrophysical Journal Letters and a PhD student at Yonsei University in Seoul, South Korea. (Previous studies of the Bullet Clus- ter with other telescopes relied on significantly less lensing data, which netted out with less precise esti- mates of the system’s mass.) “Webb’s images dramatically im- provewhatwecanmeasureinthis scene — including pinpointing the position of invisible particles known asdarkmatter,” saidKyleFinner,a co-author andanassistantscientist at IPAC at Caltech in Pasadena, Cali- fornia. All galaxies are made up of stars, gas, dust, and dark matter, which are bound together by gravity. The BulletClusterismadeupoftwo ﺗﻈﻬﺮ ﻫﺬﻩ اﻟﺼﻮرة اﻟﻤﻨﻄﻘﺔ اﻟﻤﺮﻛﺰ ﺔ ﻟﻌﻨﻘﻮد اﻟﻄﻠﻘﺔ ﺘ ﻮن ﻣﻦ واﻟﺬ ﻋﻨﻘﻮدﻳﻦ ﺿ ﻤ ﻣﺠﺮ ﺗﻢ . ــــﺐ ــــﺔ ﻓــــﻲ اﻟﺼــــﻮرة ﺑﻮاﺳــــﻄﺔ ﺗﻠﺴــــ ﻮبﺟــــ ﻤﺲو اﻟﺘﻘــــﺎط اﻟﻌــــﺪد اﻟﻬﺎﺋــــﻞ ﻣــــﻦ اﻟﻤﺠــــﺮات واﻟﻨﺠــــﻮم اﻷﻣﺎﻣ اﻟﻔﻀـﺎﺋ ﻲ اﻟﺘـﺎﺑﻊ ﻟﻮ ﺎﻟــﺔ ﻧﺎﺳـﺎ ﻓـﻲﺿـﻮء اﻷﺷـﻌﺔ ﺗﺤـﺖ اﻟــ ـ ﻤﺮاء اﻟﻘﺮ ـﺐ . ﺗﻈﻬـﺮ اﻷﺷــﻌﺔ اﻟﺴـ ﻨ ﺔ اﻟﻤﺘﻮﻫﺠــﺔ ــﺎﻟﻠﻮن اﻟـﻮرد اﻟﺘﻘﻄﻬــﺎ ﻣﺮﺻــﺪ ﺗﺸــﺎﻧﺪرا ﻟﻸﺷــﻌﺔ اﻟﺴــ ﻨ ﺔ اﻟﺘــﺎﺑﻊ ﻟﻮ ﺎﻟــﺔ ﻧﺎﺳــﺎ واﻟﺴــﺎﺧﻨﺔ اﻟـ . ﻤﺜــﻞ اﻟﻠـﻮن اﻷزرق اﻟﻤــﺎدة اﻟﻤﻈﻠﻤــﺔ ﺎﺳــﺘﺨﺪام اﻟﺘ ـــﺎﺣﺜ ﺗـــﻢ رﺳــﻢﺧﺮاﺋﻄﻬــﺎ ﺪﻗـــﺔ ﻣــﻦ ﻗﺒــﻞ اﻟ واﻟــ ﺼــﻮﻳﺮ اﻟﺘﻔﺼـــ ﻠﻲ ﻟﺘﻠﺴ ﻮب و ﺐ . ﻋﺎدةً ﻣﺎ ﺗﺘﺤﺪ اﻟﻐﺎزات واﻟﻐ ﺎرواﻟ ﻨﺠﻮم واﻟﻤﺎدة اﻟﻤﻈﻠﻤﺔ ﻓﻲ اﻟﻤﺠـﺮات ﻋﻨـﺪﻣﺎ ﺗـﺮ ﺣـ ﻂ ــﺪ اﻟﻤﺠﺮ ــﺔ ًــﺎ داﺧــﻞ ﻣ ﻤﻮﻋــﺎت أﻛــ ﺗﻌـﺮف ﺎﺳـﻢ اﻟﻌﻨﺎﻗ ﺟﺎذﺑ . ﻓـﻲ أن ﻌــﺪ اﻟﻌﻨﻘـﻮد اﻟﺮﺻﺎﺻــﻲﻏــ ﻋــﺎد اﻟﻐﺎزداﺧﻞ اﻟﻌﻨﻘﻮد واﻟﻤﺎدة اﻟﻤﻈﻠﻤﺔ ﻣﻨﻔﺼﻼن ﻣﻤﺎ ﻳﻮﻓﺮ اﻷدﻟﺔ ﺗﺪﻋﻢ وﺟﻮد اﻟﻤﺎدة اﻟﻤﻈﻠﻤﺔ اﻟ . اﻛﺘﻤــﺎﻻً ﺤﺘﻮﻳــﺎت ﻣﺠﻤﻮﻋــ ﺎت ا ﺠــﺮات ا ﺘﺼﺎدﻣﺔ . ﴏح ﺳـﺎﻧﺠﺠﻮن ﺗﺸـﺎ ا ﺆﻟـﻒ اﻟﺮﺋﻴﴘ ﻟﻠﻮرﻗﺔ اﻟﺒﺤﺜﻴﺔ ا ﻨﺸـﻮرة ﰲ ﻣﺠﻠـﺔ رﺳﺎﺋﻞ اﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴﺔ وﻃﺎﻟﺐ دﻛﺘـﻮراه ﰲ ـ ﺟﺎﻣﻌﺔ ﻳ ﻮﻧﴘ ﰲ ﺳﻴﻮل ﻛﻮرﻳـﺎ اﻟﺠﻨﻮﺑﻴـﺔ : ﺑﻔﻀﻞ " أرﺻﺎد ﺗﻠﺴﻜﻮب وﻳﺐ ﻗﻤﻨﺎ ﺑﻘﻴـﺎس ﻛﺘﻠﺔ ﻋﻨﻘﻮد اﻟﻄﻠﻘﺔ ﺑﻌﻨﺎﻳﺔ ﺑﺎﺳـﺘﺨﺪام أﻛـ ﱪ ﻣﺠﻤﻮﻋﺔ ﺑﻴﺎﻧﺎت ﻋﺪﺳﻴﺔ ﺣ ﺘﻰ اﻵن ﻣﻦ ﻧـﻮى ﻋﻨﺎﻗﻴ ﺪ ا ﺠﺮات وﺻﻮﻻً إﱃ أﻃﺮاﻓﻬﺎ ." اﻋﺘﻤــﺪت اﻟﺪراﺳــﺎت اﻟﺴــﺎﺑﻘﺔ ﻟﻌﻨﻘــﻮد اﻟﺮﺻﺎﺻﺔ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮﺑﺎت أﺧﺮى ﻋـﲆ ﺑﻴﺎﻧ ـﺎت ﻋﺪﺳـﻴﺔ أﻗ ـﻞ ﺑﻜﺜ ـ ﻣﻤــﺎ أدى إ ﱃ ﺗﻘﺪﻳﺮات أﻗﻞ دﻗﺔ ﻟﻜﺘﻠﺔ اﻟﻨﻈﺎم . ﻗﺎل ﻛﺎﻳـﻞ ﻓﻴﻨـﺮ ا ﺆﻟـﻒ ا ﺸـﺎرك وﻣﺴـﺎﻋﺪ اﻟﻌـﺎﻟﻢ ﰲ ﻣﻌﻬـﺪ أﺑﺤـﺎث اﻟﻔﻀـﺎء واﻟﻜـﻮن ) IPAC ( ﰲ ﻣﻌﻬﺪ ﻛﺎﻟﻴﻔﻮرﻧﻴﺎ ﻟﻠﺘﻜﻨﻮﻟﻮﺟﻴـﺎ ﰲ أﻳﺒﺎك ) ( ﰲ ﻣﻌﻬﺪ ﻛﺎﻟﻴﻔﻮرﻧﻴـﺎ ﻟﻠﺘﻜﻨﻮﻟﻮ ﺟﻴـﺎ ﰲ ﺑﺎﺳــﺎدﻳﻨﺎ ﰲ ﻛﺎﻟﻴﻔﻮرﻧﻴــﺎ " : ﺗﺤﺴ ـﻦ ﺻــﻮر ﺗﻠﺴﻜﻮب وﻳـﺐ ﻣـﺎ ﻳ ﻤﻜﻨﻨـﺎ ﻗﻴﺎﺳـﻪ ﰲ ﻫـﺬا ا ﺸﻬﺪ ﺑﻤﺎ ﰲ ذﻟﻚ ﺗﺤﺪﻳﺪ ﻣﻮﻗﻊ اﻟﺠﺴـﻴﻤﺎت ﻏ ا ﺮﺋﻴﺔ ا ﻌﺮوﻓﺔ ﺑﺎﺳﻢ ا ـﺎدة ا ﻈﻠﻤـﺔ ." ــــ إن ﺟﻤﻴﻊ ا ﺠﺮات ﺗﺘﻜﻮن ﻣﻦ اﻟﻨﺠﻮم واﻟﻐـﺎز واﻟﻐﺒﺎر وا ﺎدة ا ﻈﻠﻤﺔ واﻟﺘﻲ ﺗﺮﺗﺒﻂ ﺑﺒﻌﻀﻬﺎ اﻟﺒﻌﺾ ﺑﻮاﺳﻄﺔ اﻟﺠﺎذﺑﻴﺔ . ﻋﻨﻘـﻮد اﻟﻄﻠﻘـﺔ ﻳﺘﻜﻮن ﻣﻦ ﻣﺠﻤﻮﻋﺘ ﻫﺎﺋﻠﺘ ﻣﻦ ا ﺠـﺮات ﺗُﻌﺮﻓــﺎن ﺑﺎﺳــﻢ ﻋﻨﺎﻗﻴــﺪ ا ﺠــﺮات وﻫﻤــﺎ ﻣﺮﺗﺒﻄﺘــﺎن ﺑﺒﻌﻀــﻬﻤﺎ اﻟــﺒﻌﺾ ﺑ ﻮاﺳــﻄﺔ اﻟﺠﺎذﺑﻴﺔ .a ﺳﺒﺘﻤﺒﺮ - ﺃﻛﺘﻮﺑﺮ 2 0 2 5 [NASA,ESA,CSA,STScI,CXC−JamesJee(YonseiUniversity,UCDavis),SangjunCha (YonseiUniversity),KyleFinner(Caltech/IPAC)]