Free Astronomy Magazine January-February 2024 ARABIC VERSION

U Gemini North unveils the formation of dense dwarf galaxy ‘fossils’ by NOIRLab Josie Fenske ltra-compact dwarf galaxies (UCDs) are among the densest stellar groupings in the Uni- verse. Being more compact than other galaxies with similar mass, but larger than star clusters — the ob- jects they most closely resemble — these mystifying objects have defied classification. The missing piece to this puzzle has been a lack of suffi- cient transitional, or intermediate objects to study. A new galaxy sur- vey, however, fills in these missing pieces to show that many of these enigmatic objects are likely formed from the destruction of dwarf galaxies. The idea that UCDs are remnants of disrupted dwarf galaxies has been proposed since they were discov- ered over two decades ago. How- ever, previous searches have not revealed the large population of galaxies-in-transition that you would expect to find. So an interna- tional team of astronomers con- ducted a systematic search for these intermediate-stage objects around the Virgo Cluster, a grouping of thousands of galaxies in the direc- tion of the constellation Virgo. JANUARY-FEBRUARY 2024 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 30 " ﻧــــــــﻮر ــــــــ ﺟ ﻤ ﻜ " ﺸــــــــﻒﻋــــــــﻦ أﺣﺎﻓ " " ﻣﺠﺮة ﻗﺰﻣﺔ ﻛﺜ ﻔﺔ : ﻘﻠﻢ ﺟﻮزيﻓ ﻨﺴﻜﻲ ﻣﺨﺘ ﻧﻮﻳﺮﻻب ﺗﻌـﺪ ا ﺠﺮات اﻟﻘﺰﻣﺔ ﻓﺎﺋﻘﺔ اﻟﺼﻐﺮ ﻣﻦ ﺑـ اﻟﺘﺠﻤﻌﺎت اﻟﻨ ﺠﻤﻴﺔ اﻷﻛﺜﺮ ﻛﺜﺎﻓﺔ ﰲ اﻟﻜـﻮن . اً ﻧﻈﺮ ﻟﻜﻮﻧﻬﺎ أﻛﺜﺮ ﺗﺮﻛﻴﺰاً ﻣﻦ ا ﺠﺮات اﻷﺧﺮى ذات اﻟﻜﺘﻠﺔ ا ﻤﺎﺛﻠﺔ وﻟﻜﻨﻬﺎ أﻛﱪ ﻣﻦ اﻟﻌﻨﺎﻗﻴﺪ اﻟﻨﺠﻤﻴﺔ - وﻫﻲ اﻷﺟﺴﺎم اﻟﺘـﻲ ﺗﺸـﺒﻬﻬﺎ إﱃ - ﺣـﺪ ﻛﺒ ـ ﻓﻘـﺪ ﺗﺤـﺪت ﻫـﺬه اﻷﺟﺴـﺎم اﻟﻐﺎﻣﻀﺔ اﻟﺘﺼﻨﻴﻒ . ﻛﺎﻧﺖ اﻟﺤﻠﻘﺔ ا ﻔﻘـﻮد ة ﰲ ﻫﺬا اﻟﻠﻐﺰ ﻫﻲ ﻋﺪم وﺟﻮد أﺷ ﻜﺎل اﻧﺘﻘﺎﻟﻴﺔ أو وﺳﻴﻄﺔ ﻛﺎﻓﻴﺔ ﻟﻠﺪراﺳﺔ وﻣـﻊ ذﻟـﻚ ﻓـﺈن ﺎً ﻣﺴـﺤ ﺎً ﻣﺠﺮﻳـ اً ﺟﺪﻳـﺪ ﻗـﺪ أوﺟـﺪ اﻟﺤﻠﻘـﺔ ا ﻔﻘﻮدة أ وأﻇﻬﺮ ن اﻟﻌﺪﻳﺪ ﻣﻦ ﻫﺬه اﻷﺟـﺮام اﻟﻐﺎﻣﻀﺔ ﻣﻦ ا ﺤﺘﻤﻞ أن ﺗﻜﻮن ﻗﺪ ﺗﺸـﻜﻠﺖ ﻣﻦ ﺗﺪﻣ ا ﺠﺮات اﻟﻘﺰﻣﺔ . ﻟﻘﺪ ﺗﻢ اﻗﱰاح ﻓﻜﺮة أن ا ﺠﺮات اﻟﻘﺰﻣﺔ ﻏ ا ﻜﺘﻤﻠﺔ ﻫﻲ ﺑﻘﺎﻳﺎ ﻣﺠﺮات ﻗﺰﻣﺔ ﻣﻀـﻄﺮﺑﺔ ﻣﻨﺬ اﻛﺘﺸﺎﻓﻬﺎ ﻣﻨﺬ أﻛﺜـﺮ ﻣـﻦ ﻋﻘـﺪﻳﻦ ﻣـﻦ اﻟﺰﻣﻦ وﻣﻊ ذﻟﻚ ﻟﻢ ﺗﻜﺸﻒ ﻋﻤﻠﻴـﺎت اﻟﺒﺤـﺚ اﻟﺴـﺎﺑﻘﺔ ﻋـﻦ اﻟﻌـﺪد اﻟﻜﺒـ ﻣـﻦ ا ﺠـﺮات اﻻﻧﺘﻘﺎﻟﻴﺔ اﻟﺘﻲ ﺗﺘﻮﻗﻊ اﻟﻌﺜـﻮر ﻋﻠﻴﻬـﺎ . ﻟـﺬﻟﻚ أﺟﺮى ﻓﺮﻳﻖ دوﱄ ﻣـﻦ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﺑﺤﺜًـﺎ ﻣﻨﻬﺠﻴًﺎ ﻋﻦ ﻫﺬه اﻷﺟﺴﺎم ﻣﺘ ﻮﺳﻄﺔ ا ﺮﺣﻠﺔ ﻋﻨﻘﻮد ﺣﻮل اﻟﻌﺬراء وﻫﻮ ﻋﺒﺎرة ﻋﻦ ﺗﺠﻤـﻊ ﻵﻻف ا ﺠﺮات ﰲ اﺗﺠﺎه ﻛﻮﻛﺒﺔ اﻟﻌﺬراء . - ﻳﻨﺎﻳﺮ ﻓﺒﺮﺍﻳﺮ 2 0 2 4 ُﻈﻬﺮ ﻫـﺬا اﻟﺮﺳـﻢ اﻟﺘﻮﺿـﻴﺤﻲﻣﺠـﺮة ﻗﺰﻣـﺔ ﻓـﻲﺧﻀـﻢ اﻟﺘﺤـﻮل إﻟـﻰﻣﺠـﺮة ـﺘﻢ ـﺚ ﻗﺰﻣـﺔ ﻓﺎﺋﻘـﺔ اﻟﺼـﻐﺮﺣ ﺗﺠﺮ ـﺪﻫﺎ ﻣــﻦ ـ ﻃ ﻘﺎﺗﻬـﺎ اﻟــ ﺨﺎرﺟ ﺔ ﻣـﻦ اﻟﻨﺠــﻮم واﻟﻐـﺎزﺑﻮاﺳــﻄﺔ ﻣﺠـﺮة أﻛــ ﻣ . ﺠـﺎورة اﻟﻤﺠـﺮات اﻟﻘﺰﻣـﺔ ﻓﺎﺋﻘــﺔ اﻟﺘ ﻤﻌﺎ اﻟﺼﻐﺮﻫﻲﻣﻦ ﺑ ت اﻟﻨ ﻤ ﺔ اﻷﻛ ﻛﺜﺎﻓﺔ ﻓﻲ اﻟ ﻮن وﻧﻈﺮ اً ﻟ ﻮن ﻫﺬﻩ اﻷﺟﺴﺎم أﻛ إ ﺎﻣﺎ ﻣﻦ اﻟﻤ ﺠـﺮات اﻷﺧـﺮىذات اﻟﻜﺘﻠــﺔ اﻟﻤﻤﺎﺛﻠــﺔ ــﺔ ــﺪ اﻟﻨ ﻤ وﻟﻜﻨﻬــﺎ أﻛــ ﻣــﻦ اﻟﻌﻨﺎﻗ - وﻫــﻲ اﻷﺟــﺮ ﺗﺸــﺒﻬﻬﺎ ام اﻟــ إﻟـﻰﺣـﺪ ﻛﺒـ - ﻓﻘـﺪ اﺳﺘﻌﺼـﺖ ﻋﻠـﻰ اﻟﺘﺼـﻨ ﻒ . ﺎﻧـﺖ اﻟﻘﻄﻌـﺔ اﻟﻤﻔﻘـﻮدة ﻓـﻲﻫـﺬا اﻟﻠﻐـﺰﻫـﻲﻋـﺪم وﺟـﻮد أﺷــــ ﺎء ــــﺔ ﻟﻠﺪراﺳــــﺔ وﻣــــﻊ ذﻟــــﻚ ﻓــــﺈن ﻣﺴــــﺤ ــــﺔ أو وﺳــــ ﻄﺔ ﺎﻓ اﻧﺘﻘﺎﻟ ﺎً ــــﺪ اً ﺟﺪ ﻟﻠﻤﺠــــﺮات ﻤــــﻸ ﻫــــﺬﻩ اﻟﻘﻄــــﻊ ــﻮن ﻗــﺪ ــﺪ ﻣــﻦ ﻫــﺬﻩ اﻷﺟﺴــﺎم اﻟﻐﺎﻣﻀــﺔ ﻣــﻦ اﻟﻤﺤﺘﻤــﻞ أن ﺗ اﻟﻤﻔﻘـﻮدة ﻹﻇﻬــﺎر أن اﻟﻌﺪ ﺗﺸــ ﻠﺖ ﻣــﻦ ﺗــﺪﻣ اﻟﻤﺠﺮات اﻟﻘﺰﻣﺔ .