Free Astronomy Magazine May-June 2026 ARABIC VERSION

MAY-JUNE2026 CDG-2 may be composed of 99% dark matter by NASA/ESA Bethany Downer n the vast tapestry of the Uni- verse, most galaxies shine brightly acrosscosmictimeandspace.Yet a rare class of galaxies remains nearly invisible — low-surface- brightness galaxies dominated by dark matter and containing only a sparse scattering of faint stars. One such elusive object, dubbed CDG-2, may be among the most heavily dark matter-dominated galaxies ever discovered. Dark mat- terisaninvisibleformofmatter that does not reflect, emit, or ab- sorb light. The science paper detail- ingthisfindingwaspublishedin The Astrophysical Journal Letters . Detecting such faint galaxies is ex- traordinarilydifficult.Usingad- vancedstatisticaltechniques,Da- vid Li of the University of Toronto, Canada,andhisteamidentified10 previouslyconfirmedlow-surface- brightness galaxies and two addi- tionaldarkgalaxycandidatesby searchingfortightgroupingsof globularclusters—compact,spher- ical star groups typically found or- biting normal galaxies. These clus- terscansignalthepresenceofa faint, hidden stellar population. To confirm one of the dark galaxy candidates,astronomersemployed a trio of observatories: the Hubble Space Telescope, ESA’s Euclid space observatory, and the ground-based Subaru Telescope in Hawaii. Hubble’s high-resolution imaging revealed a close collection of four globularclustersinthePerseusgal- axy cluster, 300 million light-years away. Follow-upstudiesusingHubble,Eu- clid,andSubarudatathenrevealed a faint, diffuse glow surrounding the star clusters — strong evidence of an underlying galaxy. “This is the first galaxy detected solely through its globular cluster population,” said Li. “Under conser- vativeassumptions,thefourclusters representtheentireglobularcluster population of CDG-2.” ﻣﺠﺮة CDG-2 ﻣ ﻮّﻧﺔ ﻨﺴ ﺔ 99 % ﻣﻦ اﻟﻤﺎدة اﻟﻤﻈﻠﻤﺔ : ﻘﻠﻢ ﺎر ﺮا ﻓﺮ ﺮا اﻟﻤﺮﺻﺪ اﻷوروﺑﻲ اﻟـﺠﻨﻮﺑﻲ ﺗﺘـﺄﻟﻖ ﻣﻌﻈﻢ ا ﺠﺮات ﺑﻮﺿﻮح ﻋـﱪ اﻟﺰﻣـﺎن وا ﻜﺎن ﰲ اﻟﻨﺴﻴﺞ اﻟﻮاﺳﻊ ﻟﻠﻜﻮن وﻣـﻊ ذﻟـﻚ ﺗﺒﻘﻰ ﻓﺌﺔ ﻧـﺎدرة ﻣـﻦ ا ﺠـﺮات ﻏـ ﻣﺮﺋﻴـﺔ ﺗﻘﺮﻳﺒﺎً وﻫﻲ ﻣﺠـﺮات ﻣﻨﺨﻔﻀـﺔ اﻟﺴـﻄﻮع اﻟﺴـﻄﺤﻲ ﺗﻬ ـﻴﻤﻦ ﻋﻠﻴﻬ ـﺎ ا ـﺎدة ا ﻈﻠﻤ ـﺔ وﺗﺤﺘﻮي ﻋﲆ ﻋﺪد ﻗﻠﻴﻞ ﻣﻦ اﻟﻨﺠﻮ م اﻟﺨﺎﻓﺘﺔ . أﺣﺪ ﻫﺬه اﻷﺟﺮام ا ﺮاوﻏﺔ اﻟﺬي أُﻃﻠـﻖ ﻋﻠﻴـﻪ اﺳﻢ CDG-2 ﻗﺪ ﻳﻜﻮن ﻣﻦ ﺑ أﻛﺜﺮ ا ﺠـﺮات اﻟﺘﻲ ﺗﻬﻴﻤﻦ ﻋﻠﻴﻬﺎ ا ـﺎدة ا ﻈﻠﻤـﺔ اﻛﺘﺸـﺎﻓًﺎ . ﺣﺘﻰ اﻵن ا ﺎدة ا ﻈﻠﻤﺔ ﻫﻲ ﺷﻜﻞ ﻏ ﻣﺮﺋﻲ ﻣﻦ ا ﺎدة ﻻ ﻳﻌﻜﺲ اﻟﻀﻮء وﻻ ﻳﻨﺒﻌﺚ ﻣﻨﻪ وﻻ ﻳﻤﺘﺼﻪ . وﻗﺪ ﻧُﴩـت اﻟﻮرﻗـﺔ اﻟﻌﻠﻤﻴـﺔ اﻟﺘـﻲ ﺗﻔﺼّــﻞ ﻫــﺬا اﻻﻛﺘﺸــﺎف ﰲ ﻣﺠﻠ ـﺔ The ﻳﻤﺘﺼﻪ وﻗﺪ ﻧ ـ ﴩت اﻟﻮرﻗـﺔ اﻟﻌﻠﻤﻴـﺔ اﻟﺘـﻲ ﺗ ﻔﺼّـﻞ ﻫـﺬا اﻻﻛﺘﺸـﺎف ﰲ ﻣﺠﻠـﺔ رﺳـﺎﺋﻞ اﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴﺔ . ﻳُﻌﺪ رﺻﺪ ﻣﺜﻞ ﻫﺬه ا ﺠﺮات اﻟﺨﺎﻓﺘـﺔ أﻣـﺮ اً ﺑـﺎﻟﻎ اﻟﺼـﻌﻮﺑﺔ . ﺑﺎﺳـﺘﺨﺪام ﺗﻘﻨﻴﺎت إﺣﺼﺎﺋﻴﺔ ﻣﺘﻘﺪﻣﺔ ﺗﻤﻜ ﻦ دﻳﻔﻴﺪ ﱄ ﻣﻦ ﺟﺎﻣﻌﺔ ﺗﻮروﻧﺘﻮ ﰲ ﻛﻨﺪا وﻓﺮﻳﻘﻪ ﻣـﻦ ﺗﺤﺪﻳـﺪ 10 ﻣﺠﺮات ﻣ ﻨﺨﻔﻀـﺔ اﻟﺴـﻄﻮع اﻟﺴـﻄﺤﻲ ﻣﺆﻛــﺪة ﺳــﺎﺑﻘ ﺎً ﺑﺎﻹﺿــﺎﻓﺔ إﱃ ﻣﺮﺷــﺤ إﺿﺎﻓ ﻴ ﺠﺮات ﻣﻈﻠﻤـﺔ وذﻟـﻚ ﻣـﻦ ﺧـﻼل اﻟﺒﺤﺚ ﻋﻦ ﺗﺠﻤﻌ ﺎت ﻣﺘﻘﺎرﺑﺔ ﻣـﻦ اﻟﻌﻨﺎﻗﻴـﺪ اﻟﻜﺮوﻳـﺔ وﻫـﻲ ﺗﺠﻤﻌـﺎت ﻧﺠﻤﻴـﺔ ﻣﺪﻣﺠـﺔ وﻛﺮوﻳﺔ اﻟﺸﻜﻞ ﺗﻮﺟﺪ ﻋﺎدة ﰲ ﻣـﺪارات ﺣـﻮل ا ﺠﺮات اﻟﻌﺎدﻳـﺔ . ﻳﻤﻜـﻦ ﻟﻬـﺬه اﻟﻌﻨﺎﻗﻴـﺪ أن ﺗﺸــ إﱃ وﺟــﻮد ﺗﺠﻤــﻊ ﻧﺠﻤــﻲ ﺧﺎﻓــﺖ وﻣﺤﺠـﻮب ﺘﺄﻛﻴـﺪ وﻟ وﺟـﻮد أﺣـﺪ ﻣﺮﺷـﺤﻲ ا ﺠﺮات ا ﻈﻠﻤﺔ . اﺳﺘﺨﺪم ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﺛ ﻼﺛﺔ : ﻣﺮاﺻﺪ ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀـﺎﺋﻲ وﻣﺮﺻـﺪ إﻗﻠﻴﺪس اﻟﻔﻀـﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟﻮﻛﺎﻟـﺔ اﻟﻔﻀـﺎء إﻗﻠﻴﺪس اﻟﻔﻀـﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟﻮﻛﺎﻟـﺔ اﻟﻔ ﻀـﺎء اﻷوروﺑﻴــﺔ وﺗﻠﺴــﻜﻮب ﺳــﻮﺑﺎرو اﻷرﴈﰲ . ﻫﺎواي ﻛﺸﻔﺖ ﺻﻮر ﻫﺎﺑﻞ ﻋﺎﻟﻴﺔ اﻟﺪﻗﺔ ﻋـﻦ ﻣﺠﻤﻮﻋﺔ ﻣﺘﻘﺎرﺑﺔ ﻣﻦ أرﺑﻌﺔ ﻋﻨﺎ ﻗﻴﺪ ﻛﺮوﻳـﺔ ﰲ ﻋﻨﻘﻮد ﻣﺠﺮات ﺑﺮﺳـﺎوس ﻋـﲆ ﺑُﻌـﺪ 300 ﻣﻠﻴـﻮن ﺳـﻨﺔ ﺿـﻮﺋﻴﺔ . وأﻇﻬـﺮت دراﺳـﺎت ﺑﺎﺳﺘﺨﺪام ﺑ ﻴﺎﻧﺎت ﻫﺎﺑﻞ وإﻗﻠﻴﺪس وﺳـﻮﺑﺎرو ﺎً ﺗﻮﻫﺠ ﺎً ﺧﺎﻓﺘ اً ﻣﻨﺘﴩ ﻳﺤﻴﻂ ﺑﻬـﺬه اﻟ ﻌﻨﺎﻗﻴـﺪ وﻫﻮ دﻟﻴﻞ ﻗﻮي ﻋﲆ وﺟﻮد ﻣﺠﺮة ﻛﺎﻣﻨﺔ . ﻫﺬه »: وﻗﺎل ﱄ ﻫﻲ أول ﻣﺠﺮة ﻳﺘﻢ اﻛﺘﺸـﺎﻓﻬﺎ اﻋﺘﻤﺎد اً ﻓﻘﻂ ﻋﲆ ﺗﺠﻤﻊ ﻋﻨﺎﻗﻴﺪﻫﺎ اﻟﻜﺮوﻳ . «ﺔ »: وأﺿﺎف وﻓﻖ اﻓﱰاﺿـﺎت ﻣﺘﺤﻔﻈـﺔ ﺗﻤﺜـﻞ اﻟﻌﻨﺎﻗﻴﺪ اﻷرﺑﻌﺔ ﻛﺎﻣﻞ ﺗﻌﺪاد اﻟﻌﻨﺎﻗﻴﺪ اﻟﻜﺮوﻳﺔ ﰲ ﻣﺠﺮة CDG-2 «. ﺗﺸ اﻟﺘﺤﻠﻴﻼت اﻷوﻟﻴﺔ إﱃ أن ﻌـﺎن CDG-2 ﻳﻌــﺎدل ﺗﻘﺮﻳ ﺒـﺎً ﻌـﺎن ﻣﻠﻴـﻮن ﻧﺠـﻢ ﺷـﺒﻴﻪ ﺑﺎﻟﺸﻤﺲ ﺣﻴﺚ ﺗﻤﺜﻞ اﻟﻌﻨﺎﻗﻴﺪ اﻟﻜﺮوﻳﺔ ﻧﺤـﻮ ١٦ % ﻣﻦ ﻣﺤﺘﻮاﻫﺎ ا ﺮﺋﻲ . وﻣـﻦ اﻟﻼﻓـﺖ أن - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2 0 2 6