Free Astronomy Magazine March-April 2023 ARABIC VERSION

I Mysterious “ghost” stars wandering around for billions of years by NASA/ESA Bethany Downer n giant clusters of hundreds or thousands of galaxies, innumer- able stars wander among the gal- axies like lost souls, emitting a ghostly haze of light. These stars are not gravitationally tied to any one galaxy in a cluster. The nagging ques- tion for astronomers has been: how did the stars get so scattered throughout the cluster in the first place? Several competing theories in- clude the possibility that the stars were stripped out of a cluster’s galax- ies, or they were tossed around after mergers of galaxies, or they were present early in a cluster’s formative years many billions of years ago. A recent infrared survey from NASA’s Hubble Space Telescope, which looked for this so-called “in- tracluster light” sheds new light on ﻧﺠــــــــــــــﻮم " أﺷـــــــــــــ ﺎح " ﻏﺎﻣﻀــــــــــــــﺔ ﺗﺘﺠﻮل ﻣﻨﺬ ﻣﻠ ﺎرات اﻟﺴﻨ : ﻘﻠﻢ ﺑ ﺜﺎﻧﻲ داوﻧﺮ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ د ﻳﻮج ﰲ اﻟﻜﻮن ﻋﻨﺎﻗﻴﺪ ﻋﻤﻼﻗﺔ ﻣﻦ ﻣﺌـﺎت أو آﻻف ا ﺠﺮات ﺑﻬﺎ ﻧﺠﻮم ﻻ ﺣﴫ ﻟﻬﺎ ﺗﺘﺠﻮل ﺑ ا ﺠﺮ ات ﻣﺜﻞ اﻷرواح ا ﻔﻘﻮدة ﻳ ﻨﺒﻌﺚ ﻣﻨﻬﺎ ﺿﺒﺎب ﺷﺒﺤﻲ ﻣﻦ اﻟﻀﻮء ، ﻫﺬه اﻟﻨﺠﻮم ﻟﻴﺴﺖ ﻣﺮﺗﺒﻄﺔ ﺟﺎذﺑﻴًﺎ ﺑﺄي ﻣﺠﺮة واﺣﺪة ﰲ اﻟﻌﻨﻘﻮد . ـ ﻛـﺎن اﻟﺴـﺆال ا ﺤـ ﻟﻌﻠﻤـﺎء اﻟﻔﻠـﻚ : ﻛﻴـﻒ ﺗﺒﻌﺜﺮت اﻟﻨﺠﻮم ﰲ ﺟﻤﻴـ ﻊ أﻧﺤـﺎء اﻟﻌﻨﻘـﻮد ﰲ ا ﻘﺎم اﻷول . ﺗﺘﻀﻤﻦ اﻟﻌﺪﻳـﺪ ﻣـﻦ اﻟﻨﻈﺮﻳـﺎت ا ﺘﻨﺎﻓﺴﺔ إﻣﻜﺎﻧﻴﺔ ﺗﺠﺮﻳﺪ اﻟﻨﺠﻮم ﻣﻦ ﻣﺠﺮات اﻟﻌﻨﻘﻮد أو ﺗﻢ اﻟـﺘﺨﻠﺺ ﻣﻨﻬـﺎ ﺑﻌـﺪ اﻧـﺪﻣﺎج ـــ ــ ا ﺠﺮات أو أﻧﻬﺎ ﻛﺎﻧﺖ ﻣﻮﺟﻮدة ﰲ وﻗﺖ ﻣﺒﻜـﺮ ﰲ ﺳﻨﻮات ﺗﻜﻮﻳﻦ اﻟﻌﻨﻘﻮد ﻣﻨﺬ ﻋـﺪة ﻣﻠﻴـﺎرات ﻣﻦ اﻟﺴﻨ . ﻫﻨﺎك ﻣﺴﺢ ﺣﺪﻳﺚ ﺑﺎﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ﻣﻦ ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟ ﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ واﻟـﺬي ﺑﺤـﺚ ﻋـﻦ ﻣـﺎ ﻳﺴـﻤﻰ ــــــ ـــ ﻣﺎرس أﺑﺮﻳﻞ 2023 ﻳﻮﺟﺪ