Free Astronomy Magazine November-December 2023 ARABIC VERSION

largest number of shells and the largest ratio between the radii of the outermost and innermost shells. A 2016 study determined that NGC 3923 could be made up of as many as 42 distinct shells, with the outer- most layers having been created first, followed by the innermost lay- ers as the galaxies’ celestial dance slowed. Another notable characteristic of NGC 3923 is that its shells are much more subtle than those of other shell galaxies. Its shells are also in- terestingly symmetrical, while other shell galaxies are more skewed. These uncommon features are a sublime example of the unique structures that galaxies can embody depending on their specific evolu- tionary conditions. While NGC 3923 is certainly the main attraction in this expansive, 250-megapixel image, the longer one spends perusing the glittering field the more cosmic treasures can be found. Among the thou- sands of galaxies and countless fore- ground Milky Way stars speckling this image are the face-on spiral galaxies LEDA 744285 and ESO 440- 11. And near the top of the image is the extremely large gravitational lens around galaxy cluster PLCK G287.0+32.9. Discussed in scientific journals since the 1930s, gravitational lenses are predicted by Einstein’s General The- ory of Relativity, which states that a massive object, such as a cluster of galaxies, can warp spacetime. Nar- row arc-like shapes located around clusters of galaxies were first found in 1989 by NOIRLab (then NOAO) as- tronomer Roger Lynds and Stanford colleague Vahé Petrosian using the Nicholas U. Mayall 4-meter Tele- scope at Kitt Peak National Observa- tory, a Program of NSF’s NOIRLab. These extragalactic properties were interpreted as the result of strong gravitational lensing from distant galaxies in the background. Indeed, when zoomed into this image, a handful of galaxies can be seen stretched out and distorted under the gravitational influence of dark matter, the mysterious sub- stance found concentrated around clusters of galaxies. Gravitational lenses allow astronomers to explore the most profound questions of our Universe, including the nature of dark matter and the value of the Hubble constant, which defines the expansion of the Universe.  NOVEMBER-DECEMBER 2023 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 26 أﻛﱪ ﻋﺪد ﻣﻦ اﻷﺻـﺪاف وأﻛـﱪ ﻧﺴـﺒﺔ ﺑـ ﻧﺼﻒ ﻗﻄﺮ اﻷﺻﺪاف اﻟﺨﺎرﺟﻴﺔ و اﻻﺻﺪاف اﻷﻋﻤﻖ . ﺗﻮﺻﻠﺖ دراﺳﺔ أﺟﺮﻳﺖ ﻋـﺎم 2016 إﱃ أن ا ﺠﺮة NGC 3923 ﻳﻤﻜﻦ أن ﺗﺘﻜـﻮن ﻣﻦ ﻣﺎ ﻳﺼﻞ إﱃ 42 ﻏﻼﻓًﺎ ﻣﺨﺘﻠﻔًﺎ ﺗـﻢ ﺣﻴﺚ إﻧﺸــﺎء اﻟﻄﺒﻘــﺎت اﻟﺨﺎرﺟﻴــﺔ أوﻻً ﺗﻠﻴﻬــﺎ اﻟﻄﺒﻘـﺎت اﻟﺪاﺧﻠﻴــﺔ ﻣــﻊ ﺗﺒـ ﺎﻃﺆ رﻗﺼــﺔ ا ﺠﺮات اﻟﺴﻤﺎوﻳﺔ . ﻣﻦ اﻟﺨﺼﺎﺋﺺ اﻟﺒـﺎرزة اﻷﺧﺮى ﻟـ NGC 3923 أن أﻏﻠﻔ ﺘ ﻬﺎ أﻛﺜﺮ دﻗﺔ ﻣـﻦ ﺗﻠـﻚ ا ﻮﺟـﻮدة ﰲ ا ﺠـﺮات اﻟﺼـﺪﻓﻴﺔ اﻷﺧﺮى ﻛﻤﺎ أن أﺻﺪ اﻓﻬﺎ ﻣﺘﻨـﺎﻇﺮة ﺑﺸـﻜﻞ ﻣﺜ ﻟﻼﻫﺘﻤﺎم ﰲ ﺣ أن ا ﺠﺮات اﻟﺼﺪﻓﻴﺔ اﻷﺧﺮى أﻛﺜﺮ اﻧﺤﺮاﻓًـﺎً . ﻫـﺬه ا ﻴـﺰات ﻏـ ا ﺄﻟﻮﻓﺔ ﻫﻲ ﻣﺜﺎل راﺋﻊ ﻋﲆ اﻟﻬﻴﺎﻛﻞ اﻟﻔﺮﻳﺪة اﻟﺘ ﻲ ﻳﻤﻜﻦ أن ﺗﺠﺴـﺪﻫﺎ ا ﺠـﺮات اﻋﺘﻤـﺎد اً ﻋﲆ ﻇﺮوﻓﻬﺎ اﻟﺘﻄﻮرﻳﺔ ا ﺤﺪدة . ﺑﺎﻟﻄﺒﻊ ﻓﺈ ن NGC 3923 ﻲﻫ ﻋﺎﻣﻞ اﻟﺠﺬب اﻟﺮﺋﻴــ ـ ﴘﰲ ﻫــﺬه اﻟﺼــﻮرة ﺑﺪﻗــﺔ 250 ﻣﻴﺠﺎﺑﻜﺴــﻞ وﻋﻨــﺪ اﻟــﺘﻤﻌﻦ ﰲ ﻣﺘﺎﺑﻌــﺔ G287.0 اﻟﺤﻘﻞ ا ﺘﻸﻟﺊ ﻳﻤﻜﻦ اﻟﻌﺜﻮر ﻋﲆ ا ﺰﻳﺪ ﻣـﻦ اﻟﻜﻨﻮز اﻟﻜﻮﻧﻴﺔ . ﻣﻦ ﺑ آﻻف ا ﺠﺮات وﻋﺪد ﻻ ﻳﺤﴡ ﻣﻦ ﻧﺠﻮم درب اﻟﺘﺒﺎﻧﺔ اﻟﺘﻲ ﺗﻈﻬﺮ ﰲ ﻫﺬه اﻟﺼﻮرة ﻫﻨﺎك ا ﺠﺮﺗـﺎن اﻟﻠﻮﻟﺒﻴﺘـﺎن LEDA744285 و ESO 440-11 وﺑﺎﻟﻘﺮب ﻣﻦ اﻟﺠﺰء اﻟﻌﻠﻮي ﻣﻦ اﻟﺼﻮرة ﺗﻮﺟﺪ ﻋﺪﺳﺔ اﻟﺠﺎذﺑﻴـﺔ اﻟﻜﺒـ ة ﻟﻠﻐﺎﻳـﺔ ﺣـﻮل اﻟﻌﻨﻘـﻮد ا ﺠــﺮي PLCK G287.0+32.9 . ﺗﻤ ــﺖ ﻣﻨﺎﻗﺸــﺔ ﻋﺪﺳ ـﺎت اﻟﺠﺎذﺑﻴــﺔ ﰲ ا ﺠ ـﻼت اﻟﻌﻠ ﻤﻴﺔ ﻣﻨﺬ ﺛﻼﺛﻴﻨﻴﺎت اﻟﻘﺮن اﻟﻌﴩﻳﻦ وﻗﺪ ﺗﻢ اﻟﺘﻨﺒﺆ ﺑﻬﺎ ﻣﻦ ﺧـﻼل ا ﻟﻨﻈﺮﻳـﺔ اﻟﻨﺴـﺒﻴﺔ اﻟﻌﺎﻣـﺔ ﻷﻳﻨﺸـﺘﺎﻳﻦ واﻟﺘـﻲ ﺗـﻨﺺﻋـﲆ ن أ اﻷﺟﺴﺎم اﻟﻀﺨﻤﺔ ﻣﺜﻞ ﻋﻨﻘﻮد ﻣﻦ ا ﺠـﺮات ﻳﻤﻜﻦ أن ﺗﺸﻮه اﻟﺰﻣﻜﺎن . ﺗـﻢ اﻟﻌﺜـﻮر ﻋـﲆ اﻷﺷﻜﺎل اﻟﻀﻴﻘﺔ اﻟﺘﻲ ﺗﺸﺒﻪ اﻟﻘﻮس واﻟﺘـﻲ ﻮﺟﺪ ﺗ ﻋﻨﻘﻮد ﺣﻮل ﻣﻦ ا ﺠﺮات ﻷ ول ﻣـﺮة ﰲ ﻋﺎم 1989 ﻣﻦ ﻗﺒﻞ ﻋﺎﻟﻢ اﻟﻔﻠﻚ ﻣﻦ ﻣﺨﺘـﱪ ﻧﻮﻳﺮﻻب ﺛﻢ ) ا ﺮﺻﺪ اﻟـﻮﻃﻨﻲ ﻟﻌﻠـﻢ اﻟﻔﻠـﻚ اﻟﺒﴫي ( روﺟﺮ ﻟﻴﻨـﺪز وزﻣﻴﻠـﻪ ﰲ ﺟﺎﻣﻌـﺔ ﺳﺘﺎﻧﻔﻮرد ﻓﺎه ﺑﱰوﺳﻴﺎن __ ﺳﺘﺎﻧﻔﻮرد ﻓﺎه ﺑﱰوﺳﻴﺎن وذﻟﻚ ﺑﺎﺳـﺘﺨﺪام ﺗﻠﺴﻜﻮب ﻧﻴﻜﻮﻻس ﻳـﻮ ﻣﺎﻳـﺎل اﻟـﺬي ﻳﺒﻠـﻎ أرﺑﻌﺔ أﻣﺘﺎر ﰲ ﻣﺮﺻﺪ ﻛﻴﺖ ﺑﻴﻚ اﻟﻮﻃﻨﻲ ﻫﻮ و ﺑﺮﻧﺎﻣﺞ ﻟ ﻠﻤﺨﺘﱪ اﻟﻮﻃﻨﻲ ﻷﺑﺤﺎث ﻋﻠﻢ اﻟﻔﻠﻚ اﻟﺒﴫي واﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ) ﻧﻮﻳﺮﻻب ( اﻟﺘﺎﺑﻊ ﻟ ﻠﻤﺆﺳﺴﺔ اﻟﻮﻃﻨﻴﺔ ﻟﻠﻌﻠﻮم . ﻟﻘﺪ ﺗﻢ ﺗﻔﺴـ ﻫـﺬه اﻟﺨﺼـﺎﺋﺺ ﺧـﺎرج ا ﺠﺮة ﻋﲆ أﻧﻬﺎ ﻧﺘﻴﺠـﺔ ﻟﻌﺪﺳـﺔ اﻟﺠﺎذﺑﻴـﺔ اﻟﻘﻮﻳﺔ ﻣﻦ ا ﺠﺮات اﻟﺒﻌﻴﺪة ﰲ اﻟﺨﻠﻔﻴﺔ . ﺣﻘﻴﻘﺔ ﻋﻨﺪ ﺗﻜﺒ ﻫـﺬه اﻟﺼـﻮرة اﻟﺮاﺋﻌـﺔ ﻳﻤﻜﻦ رؤﻳﺔ ﻣﺠﻤﻮﻋﺔ ﻣﻦ ا ﺠـﺮات ﻣﻤﺘـﺪة وﻣﺸﻮﻫﺔ ﺗﺤﺖ ﺗﺄﺛ ﺟﺎذﺑﻴﺔ ا ﺎدة ا ﻈﻠﻤﺔ وﻫﻲ ا ﺎدة اﻟﻐﺎﻣﻀﺔ اﻟﺘﻲ ﺗﻢ اﻟﻌﺜﻮر ﻋﻠﻴﻬـﺎ واﻟﺘﻲ ﺗﱰﻛﺰ ﺣﻮل ﻋﻨﺎﻗﻴﺪ ﻣﻦ ا ﺠﺮات . ﺗﺴﻤﺢ ﻋﺪﺳـﺎت اﻟﺠﺎذﺑﻴـﺔ ﻟﻌﻠﻤـﺎء اﻟﻔﻠـﻚ ﺑﺎﺳﺘﻜﺸــﺎف أﻋﻤــﻖ ﻟﻠﻜــﻮن وﻣﺤﺎوﻟــﺔ اﻟﺤﺼﻮل ﻋﲆ إﺟﺎﺑﺎت ﻣﺘﻌﻠﻘﺔ ﺑﺎﻟﻜﻮن ﺑﻤﺎ ﰲ ذﻟﻚ ﻃﺒﻴﻌﺔ ا ﺎدة ا ﻈﻠﻤﺔ وﻗﻴﻤﺔ ﺛﺎﺑﺖ ﻫﺎﺑﻞ اﻟﺬي ﻳﺤﺪد ﺗﻮﺳﻊ اﻟﻜﻮن . ـــــــﺘﻢ ﻋـــــــﺮضاﻟﻄ ﻘـــــــﺎت ﺗﺸـــ ﮫ اﻟﻤﺘﻨـــﺎﻇﺮة اﻟـــ اﻟ ﺼـــــــــــــــــــــــــﻠﺔ ﻟﻠﻤﺠـــــــــــــــــــــــــﺮة اﻟﺼـﺪﻓ ﺔ NGC 3923 ﻓـــــــــــﻲﻫـــــــــــﺬﻩ اﻟﺼـــــــــــﻮرة ـــــــــــــــــــﺎﻟﻤﺠﺮات ـــــــــــــــــــﺔ اﻟﻐﻨ اﻟﺘﻘﻄﺘﻬـــــــــــــــــــــﺎ واﻟـــــــــــــــــــــ ـــــــــــــــــــــــــــﺎﻣ ا اﻟﻄﺎﻗـــــــــــــــــــــــــــﺔ اﻟﻤﻈﻠﻤـــــــــــﺔ . ﻤـــــــــــﺎ ﺗـــــــــــﻢ اﻟﺘﻘـﺎطﻋﻨﻘـﻮد ﻣﺠــﺮي ﺿــــــــــــــ ﻢﻗﺮ ــــــــــــــﺐﻣﻤــــــــــــــﺎ ﻌــــــــــــــــــــﺮضاﻟﻈـــــــــــــــــــــﺎﻫﺮة اﻟﻤﻌﺮوﻓــــــﺔ ﺎﻟﻌﺪﺳـــــــ ﺔ اﻟﺘﺜﺎﻗﻠ ﺔ . [DESI Legacy Imaging Surveys/ LBNL/DOE& KPNO/CTIO/NOIR- Lab/NSF/AURA. Imageprocess- ing: T.A. Rector (UniversityofAlaska Anchor- age/NSF’s NOIR-Lab), M. Zamani, R. Colombari &D. deMartin(NSF’s NOIRLab)] ﻧﻮﻓﻤﺒﺮ - ﺩﻳﺴﻤﺒﺮ 2 0 2 3