Free Astronomy Magazine March-April 2023 ARABIC VERSION

47 the mystery. The new Hubble obser- vations suggest that these stars have been wandering around for billions of years, and are not a product of more recent dynamical activity in- side a galaxy cluster that would strip them out of normal galaxies. The survey included 10 galaxy clus- ters as far away as nearly 10 billion light-years. These measurements must be made from space because the faint intracluster light is 10,000 times dimmer than the night sky as seen from the ground. The survey reveals that the fraction of the intracluster light relative to the total light in the cluster remains constant, looking over billions of years back into time. “This means that these stars were already home- less in the early stages of the clus- ter’s formation,” said James Jee of Yonsei University in Seoul, South Korea. His results have being pub- lished in the January 5 issue of Na- ture magazine. Stars can be scattered outside of their galactic birthplace when a galaxy moves through gaseous mate- rial in the space be- tween galaxies, as it orbits the center of the cluster. In the process, drag pushes gas and dust out of the galaxy. However, based on the new Hubble survey, Jee rules out this mechanism as the primary cause for the intracluster star pro- duction. That’s because the intracluster light fraction would increase over time to the present if stripping is the main player. But that is not the case in the new Hubble data, which show a constant frac- tion over billions of years. “We don’t exactly know what made them homeless. Current theories cannot explain our results, but somehow they were produced in large quantities in the early uni- verse,” said Jee. “ In their early form- ative years, galaxies might have been pretty small and they bled stars pretty easily because of a weaker gravitational grasp.” “If we figure out the origin of intra- cluster stars, it will help us under- stand the assembly history of an entire galaxy cluster, and they can serve as visible tracers of dark mat- ter enveloping the cluster,” said Hyungjin Joo of Yonsei University, the first author of the paper. Dark matter is the invisible scaffold- ing of the universe, which holds galaxies, and clusters of galaxies, to- gether. If the wandering stars were produced through a comparatively recent pinball game among galax- ies, they do not have enough time to scatter throughout the entire gravitational field of the cluster and therefore would not trace the distri- bution of the cluster’s dark matter. But if the stars were born in the cluster’s early years, they will have fully dispersed throughout the clus- ter. This would allow astronomers to use the wayward stars to map out the dark matter distribution across the cluster. This technique is new and comple- mentary to the traditional method of dark matter mapping by measur- ing how the entire cluster warps light from background objects due to a phenomenon called gravita- tional lensing. Intracluster light was first detected in the Coma cluster of galaxies in 1951 by Fritz Zwicky, who reported that one of his most interesting dis- coveries was observing luminous, faint intergalactic matter in the clus- ter. Because the Coma cluster, con- taining at least 1,000 galaxies, is one of the nearest clusters to Earth (330 million light-years), Zwicky was able to detect the ghost light even with a modest 18-inch telescope. NASA’s James Webb Space Tele- scope’s near-infrared capability and sensitivity will greatly extend the search for intracluster stars deeper into the universe, and therefore should help solve the mystery.     " اﻟﻀﻮء ا ﱰاﻛﻢ " ﻳﺴﻠﻂ اﻟﻀﻮء ﻋـﲆ اﻟﻠﻐـﺰ . ﺗﺸ أرﺻﺎد ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﺠﺪﻳـﺪة إﱃ أن ﻫﺬه اﻟﻨﺠﻮم ﻛﺎﻧﺖ ﺗﺘﺠﻮل ﻠﻴـﺎرات اﻟﺴـﻨ وﻟﻴﺴﺖ ﻧﺘﺎﺟًﺎ ﻟﻨﺸﺎط دﻳﻨﺎﻣﻴﻜﻲ ﺣﺪﻳﺚ داﺧﻞ ا ﻋﻨﻘﻮد ﺠﺮات ﻣـﻦ ﺷـﺄﻧﻬﺎ ﺗﺠﺮﻳـﺪﻫﺎ ﻣـﻦ ا ﺠﺮات اﻟﻌﺎدﻳﺔ . ﺷﻤﻞ ا ﺴـﺢ ﻋﴩـة ﻋﻨﺎﻗﻴـﺪ ﻣﺠﺮﻳـﺔ ﻋـﲆ ﻣﺴﺎﻓﺔ ﺣﻮاﱄ ١٠ ﻣﻠﻴﺎر ﺳﻨﺔ ﺿﻮﺋﻴﺔ ، ﻳﺠـﺐ إﺟﺮاء ﻫﺬه اﻟﻘﻴﺎﺳﺎت ﻣﻦ اﻟﻔﻀﺎء ﻷن اﻟﻀﻮء اﻟﺨﺎﻓـﺖ داﺧـﻞ اﻟﻌﻨﻘـﻮ د ﻫـﻮ أﺿـﻌﻒ ﺑــ ١٠,٠٠٠ ﻣﺮة ﻣﻦ ﺳﻤﺎء اﻟﻠﻴﻞ ﻛﻤﺎ ﺗُـﺮى ﻣـﻦ اﻷرض . ﻳﻜﺸﻒ ا ﺴﺢ أن ﺟﺰء اﻟﻀﻮء داﺧﻞ اﻟﻌﻨﻘـﻮد ﺑﺎﻟﻨﺴﺒﺔ ﻟﻠﻀﻮء اﻟﻜﲇ ﰲ اﻟﻜﺘﻠـﺔ ﻳﻈـﻞ ﺛﺎﺑﺘًـﺎ ﺑﺎﻟﻨﻈﺮ إﱃ ﻣﻠﻴﺎرات اﻟﺴﻨ ا ﺎﺿـﻴﺔ، ﻳﻘـﻮل ﺟﻴﻤﺲ ﺟﻲ ﻣﻦ ﺟﺎﻣﻌﺔ ﻳﻮﻧﴘ ﰲ اﻟﻌﺎﺻـﻤﺔ ﺳﻴﻮل ﺑﻜﻮرﻳﺎ اﻟﺠﻨﻮﺑﻴﺔ " : إن ﻫﺬا ﻳﻌﻨﻲ ﺄن ﺑـ اﻟﻨﺠ ﺗﻠﻚ ـ ﻮم ﻛﺎﻧﺖ ﺑﻼ وﻃــﻦ ﻣﻨـﺬ ا ﺮاﺣـﻞ اﻷوﱃ ﻣـــﻦ ﻋﻤﻠﻴ ــﺔ ﺗﻜ ــﻮﻳﻦ اﻟﻌﻨﻘ ــﻮد ." ــــــ ـــــ ــــــــــ ﻧُﴩت اﻟﻨﺘﺎﺋﺞ ﰲ ﻋﺪد ٥ ﻳﻨﺎﻳﺮ ﻣﻦ ﻣﺠﻠﺔ اﻟﻄﺒﻴﻌﺔ نإ . اﻟﻨﺠﻮم ﻳﻤﻜــﻦ أن ﺗﺘﺒﻌﺜــﺮ ﺧــﺎرج ا ﺠﺮات اﻟﺘﻲ وﻟﺪت ﺑﻬﺎ ﻋﻨﺪﻣﺎ ﺗﺘﺤـﺮك ا ةﺠــﺮ ﻋ ـﱪ ﻣ ـﺎدة ﻏﺎزﻳﺔ ﰲ اﻟﻔﻀﺎء ﺑ ا ﺠﺮات ﺣﻴــﺚ ﺗــﺪور ﺣــﻮل ﻣﺮﻛــﺰ اﻟﻌﻨﻘﻮد ، ﺧﻼل اﻟﻌﻤﻠﻴﺔ ﻳﺪﻓﻊ اﻟﺴﺤﺐ اﻟﻐﺎز واﻟﻐﺒﺎر ﺧـﺎرج ا ﺠﺮة وﻣـﻊ ذﻟـﻚ ﺑﻨـﺎءً ﻋـﲆ ﻣﺴﺢ ﻫﺎﺑﻞ اﻟﺠﺪﻳﺪ اﺳﺘﺒﻌﺪ ت ﻫﺬه اﻵﻟﻴﺔ ﺑﺎﻋﺘﺒﺎرﻫﺎ اﻟﺴـﺒﺐ اﻟﺮﺋﻴﺲ ﻻﻧﺘﺸﺎر اﻟﻨﺠﻮم داﺧﻞ اﻟﻌﻨﻘﻮد وذﻟﻚ ﻷن ﺟﺰء اﻟﻀﻮء داﺧﻞ اﻟﻌﻨﻘﻮد ﺳﻴﺰداد ﺑﻤﺮور اﻟﻮﻗﺖ ﺣﺘﻰ اﻟﻮﻗﺖ اﻟﺤـﺎﴐ إذا ﻛﺎن اﻟﺘﺠﺮﻳﺪ ﻫﻮ اﻟﻼﻋﺐ اﻟﺮﺋﻴﺲ، ﻟﻜﻦ ﻫﺬا ﻟﻴﺲ ﻫﻮ اﻟﺤﺎل ﰲ ﺑﻴﺎﻧـﺎت ﻫﺎﺑـﻞ اﻟﺠﺪﻳـ ﺪة ـ اﻟﺘﻲ ﺗﻈﻬﺮ ﺟﺰءًا ﺛﺎﺑﺘًﺎ ﻋـﲆ ﻣـﺪى ﻣﻠﻴـﺎرات اﻟﺴﻨ . ﻻ ﻧﻌﺮف ﺑﺎﻟﻀﺒﻂ ﻣﺎ اﻟﺬي ﺟﻌﻠﻬﻢ ﺑﻼ . ﻣﺄوى ﻻ ﻳﻤﻜﻦ ﻟﻠﻨﻈﺮﻳﺎت اﻟﺤﺎﻟﻴﺔ أن ﺗﻔﺴ ﺮ ـ ﻧﺘﺎﺋﺠﻨـﺎ وﻟﻜـﻦ ﺑﻄﺮﻳﻘـﺔ ﻣــﺎ ﺗـﻢ إﻧﺘﺎﺟﻬــ ﺎ ﺑﻜﻤﻴﺎت ﻛﺒ ة ﰲ اﻟﻜﻮن ا ﺒﻜﺮ ، ﰲ " ﻗﺎل ﺟﻲ ﺳﻨﻮات ﺗ ﻜﻮﻳﻨﻬﺎ ا ﺒﻜﺮة رﺑﻤﺎ ﻛﺎﻧﺖ ا ﺠـﺮات ﺻﻐ ة ﺟﺪًا وﻧﺰﻓﺖ اﻟﻨﺠﻮم ﺑﺴـﻬﻮﻟﺔ ﻛﺒـ ة ﺑﺴـﺒﺐ ﻓﻬ ـﻢ اﻟﺠﺎذﺑﻴ ـﺔ اﻷﺿـﻌﻒ ". ﻗــﺎل ﻫﻴﻮﻧﻐﺠ ﺟـﻮ ﻣـﻦ ﺟﺎﻣﻌـﺔ ﻳﻮﻧﺴـ إذا "ـﻲ اﻛﺘﺸﻔﻨﺎ أﺻﻞ اﻟﻨﺠﻮم داﺧﻞ اﻟﻌﻨﻘﻮد ﻓﺴﻮف ﻳﺴـﺎﻋﺪﻧﺎ ذﻟ ـﻚ ـ ﰲ ﻓ ـ ﻬﻢ ﺗــﺎر ﻳﺦ اﻟﺘﺠﻤ ـﻊ ﺠﻤﻮﻋﺔ ﻣﺠﺮات ﻛﺎﻣﻠـﺔ وﻳﻤﻜـﻦ أن ﺗﻜـﻮن ﺑﻤﺜﺎﺑﺔ أدوات ﺗﺘﺒﻊ ﻣﺮﺋﻴـﺔ ﻟﻠﻤـﺎدة ا ﻈﻠﻤـﺔ اﻟﺘﻲ ﺗﻐﻠﻒ اﻟﻌﻨﻘﻮد ." ، ا ﺆﻟﻒ اﻷول ﻟﻠﻮرﻗـﺔ . ا ـﺎدة ا ﻈﻠﻤـﺔ ﻫـﻲ رواﺑـﻂ ﻏـ ﻣﺮﺋﻴ ـﺔ ــــــــ ﻟﻠﻜـﻮن واﻟ ﺘ ـﻲ ﺗﺠﻤـﻊ ا ﺠـﺮات وﻋﻨﺎﻗﻴ ـﺪ ا ﺠﺮات ﻣﻌًﺎ . إذا ﺗﻢ إﻧﺘﺎج اﻟﻨﺠـﻮم ا ﺘﺠﻮﻟـﺔ ﻣﻦ ﺧﻼل ﻟﻌﺒﺔ اﻟﻜـﺮة واﻟـﺪﺑﺎﺑﻴﺲ اﻟﺤﺪﻳﺜـﺔ ﻧﺴﺒﻴًﺎ ﺑ ا ﺠﺮات ﻓﻠﻦ ﻳﻜﻮن ﻟـﺪﻳﻬ ﺎ اﻟﻮﻗـﺖ اﻟﻜ ـﺎﰲ ﻟﻠﺘﺸ ـﺘﺖ ﰲ ﺟﻤﻴــﻊ أﻧﺤ ـﺎء ﻣﺠ ـﺎل اﻟﺠﺎذﺑﻴﺔ ﻟﻠﻌﻨﻘﻮد وﺑﺎﻟﺘﺎﱄ ﻟـﻦ ﺗﺘﺒـﻊ ﺗﻮزﻳـﻊ ا ﺎدة ا ﻈﻠﻤـﺔ ﰲ اﻟﻌﻨﻘـﻮد وﻟﻜـﻦ إذا وﻟـﺪت اﻟ ﻨﺠﻮم ﰲ اﻟﺴﻨﻮات اﻷوﱃ ﻟﻠﻌﻨﻘﻮد ﻨﺘﴩ ـ ﻓﺴﺘ ﺑﺎﻟﻜﺎﻣﻞ ﰲ ﺟﻤﻴﻊ أﻧﺤﺎء اﻟﻌﻨﻘـﻮد . ﺳﻴﺴـﻤﺢ ﻫﺬا ﻟﻌﻠﻤﺎء اﻟﻔﻠﻚ ﺑﺎﺳﺘﺨﺪام اﻟﻨﺠﻮم اﻟﻀـﺎﻟﺔ ﻟﺮﺳﻢ ﺧﺮﻳﻄﺔ ﻟﺘﻮزﻳﻊ ا ـﺎدة ا ﻈﻠﻤـﺔ ﻋـﱪ اﻟﻌﻨﻘـﻮد . ﻫـﺬه اﻟﺘﻘﻨﻴـﺔ ﺟﺪﻳ ـﺪة وﻣﻜﻤﻠ ـﺔ ﻟﻠﻄﺮﻳﻘـﺔ اﻟﺘﻘﻠﻴﺪﻳـﺔ ﻟﺮﺳـﻢ ﺧـﺮاﺋﻂ ا ـﺎدة ا ﻈﻠﻤـﺔ ﻣـﻦ ﺧـﻼل ﻗﻴـﺎس ﻛﻴﻔﻴـﺔ ﻗﻴـ ﺎم ا ﺠﻤﻮﻋﺔ ﺑﺄﻛﻤﻠﻬﺎ ﺑﺈﻟﺘﻮاء اﻟﻀﻮء ﻣﻦ أﺟﺴﺎم اﻟﺨﻠﻔﻴ ـﺔ ﺑﺴـﺒﺐ ﻇــﺎﻫﺮة ﺗﺴـﻤﻰ ﻋﺪﺳـﺔ اﻟﺠﺎذﺑﻴﺔ . ﺗﻢ اﻛﺘﺸﺎف اﻟﻀﻮء داﺧﻞ اﻟﻌﻨﻘـﻮد ﻷول ﻣﺮة ﰲ ﻣﺠﻤﻮﻋﺔ اﻟﻜﻮﻣﺎ ﻣﻦ ا ﺠـﺮات ﰲ ﻋﺎم ١٩٥١ ﻣﻦ ﻗﺒﻞ ﻓﺮﻳﺘﺰ زوﻳﻜﻲ اﻟﺬي ذﻛـﺮ أن أﺣﺪ أﻛﺜﺮ اﻛﺘﺸﺎﻓﺎﺗﻪ إﺛﺎرة ﻟﻼﻫﺘﻤﺎم ﻛـﺎن رﺻﺪ ﻣﺎدة ﻣﻀﻴﺌﺔ وﺧﺎﻓﺘﺔ ﺑـ ا ﺠـﺮات ﰲ اﻟﻌﻨﻘﻮد . ﻧﻈﺮًا ﻷن ﻋﻨﻘﻮد ﻛﻮﻣﺎ ا ﺠﺮي اﻟﺬي ﻳ ﺤﺘﻮي ﻋﲆ ﻣﺎ ﻻ ﻳﻘﻞ ﻋﻦ ١٠٠٠ ، ﻣﺠﺮة ﻫﻮ اﺣﺪ أﻗﺮب اﻟﻌﻨﺎﻗﻴـﺪ إﱃ اﻷرض ) ٣٣٠ ﻣﻠﻴـﻮن ( ﺳﻨﺔ ﺿﻮﺋﻴﺔ ، ﻓﻘـﺪ ﺗﻤﻜـﻦ ) زﻓﻴﻜـﻲ ( ﻣـﻦ اﻛﺘﺸﺎف ﺿـﻮء اﻷﺷـﺒﺎح ﺣﺘـﻰ ﺑﺎﺳـﺘﺨﺪام ﺗﻠﺴﻜﻮب ١٨ ﺑﻮﺻﺔ ﻣﺘﻮاﺿﻊ . ﺳﺘﻌﻤﻞ ﻗـﺪرة وﺣﺴﺎﺳﻴﺔ ﻧﻄﺎق ﺟـﻴﻤﺲ وﻳـﺐ اﻟﻔﻀـ ﺎﺋﻲ ﻟﻸﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء اﻟﻘﺮﻳﺒـﺔ ﻣـﻦ وﻛﺎﻟـﺔ ﻧﺎﺳﺎ ﻋﲆ ﺗﻮﺳﻴﻊ ﻧﻄﺎق اﻟﺒﺤﺚ ﻋـﻦ اﻟﻨﺠـﻮم داﺧﻞ اﻟﻌﻨﻘﻮد ﰲ ﻋﻤﻖ اﻟﻜﻮن ، وﺑﺎﻟﺘﺎﱄ ﻳﺠﺐ أن ﺗﺴﺎﻋﺪ ﰲ ﺣﻞ اﻟﻠﻐﺰ . ﻣﺎرس أﺑﺮﻳﻞ 2023 ٤٧ ﺻــــﻮر اﻟﺘﻘﻄـــــﺖ ﺑﻮا ﺳـــــﻄﺔ ﻣـــــﻦ اﻟﻤﺠـــــﺮات ﻫـــــﺎﺋﻠﺘ ﺗﻠﺴــــ ﻮبﻫﺎﺑـــــﻞ اﻟﻔﻀـــــﺎﺋﻲ ﻟﻤﺠــــﺮ ﺗﺴﻤﻰ MOO J1014 + 0038 ) اﻟﻠﻮﺣﺔ اﻟ ﺴﺮى و( SPT-CL J2106-5844 ) اﻟﻠﻮﺣﺔ اﻟ ﻤ .( ُﻢ اﻟﻠـﻮن اﻷزرق اﻟﻤﻀـﺎفﺻـﻨﺎﻋ ﺎ ﻣـﻦ ﺑ ﺎﻧـﺎتﻫﺎﺑـﻞ ﻇـﺎﻫﺮة ﺗﺴـﻤﻰ اﻟﻀـﻮء داﺧﻞ اﻟﻌﻨﻘﻮد . ﺘﺘﺒﻊ ﻫﺬا اﻟﺘﻮﻫﺞ اﻟـ ـ ـﺔ اﻟﺘﻮز ـﻊ اﻟﺴـﻠﺲ ﻟﻠﻀـ ﺨﺎﻓﺖ ﻟﻠﻐﺎ ﻮء ﻣـﻦ اﻟﻨﺠـﻮم اﻟﻤﺘﺠﻮﻟــﺔ اﻟﻤﻨﺘﺸــﺮة ﻋــ اﻟﻌﻨﻘــﻮد . اﻟﺴـﻨ ﻣﻨــﺬ ﻼﻳــ ﺗــﻢ إﻟﻘــﺎء اﻟﻨﺠــﻮم ﻣــﻦ اﻟﻤﺠــﺮات اﻟﻤﺠﺮات اﻷم ، واﻵن ﺗﻨﺠﺮف ﻋ اﻟﻔﻀﺎء ﺑ ] . ﻧﺎﺳﺎ ، و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ ، STScI ، ﺟ ﻤﺲﺟﻲ ) ﺟﺎﻣﻌﺔ ﻳﻮﻧﺴﻲ .( ـ ﻣﻌﺎﻟ ﺠﺔ اﻟﺼﻮر : ﺟﻮزﻒ دﻳ ﺎﺳ ﻮال (STScI)]