Free Astronomy Magazine July-August 2024 ARABIC VERSION

surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of ma- terial and therefore is harder to erode. Astronomers estimate that the Horsehead has about five mil- his image showcases three views of one of the most distinctive objects in our skies, the Horsehead Nebula. The first image (left), released in November 2023, features the Horsehead Nebula as seen in visible light by ESA’s Euclid telescope, which has contributions from NASA. The second image (middle) shows a view of the Horsehead Nebula in near-infrared light from NASA’s Hubble Space Telescope. This image reveals a beautiful, delicate structure that is normally obscured by dust. The third image (right) features a new view of the Horsehead Nebula from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) instrument. [NASA, ESA, CSA, Karl Misselt (University of Arizona), Alain Abergel (IAS, CNRS), Mahdi Zamani The Euclid Consortium, Hubble Heritage Project (STScI, AURA)] lion years left before it too disinte- grates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure. The Horsehead Nebula is a well- known photodissociation region, or PDR. In such a region, ultraviolet (UV) light from young, massive stars creates a mostly neutral, warm area of gas and dust between the fully ionized gas surrounding the mas- sive stars and the clouds in which they are born. This UV radiation strongly influences the chemistry of these regions and acts as a signifi- cant source of heat. These regions occur where interstel- lar gas is dense enough to remain mostly neutral, but not dense enough to prevent the penetration of UV light from massive stars. The light emitted from such PDRs pro- vides a unique tool to study the physical and chemical processes that drive the evolution of interstellar matter in our galaxy, and through- out the universe from the early era of vigorous star formation to the present day. Due to its proximity and its nearly edge-on geometry, the Horsehead Nebula is an ideal target for as- tronomers to study the physical structures of PDRs and the molecu- lar evolution of the gas and dust within their respective environ- ments, and the transition regions between them. It is considered one of the best regions in the sky to study how radiation interacts with interstellar matter. Thanks to Webb’s MIRI and NIRCam instruments, an international team of astronomers has revealed for the first time the small-scale structures of the illuminated edge of the Horsehead. As UV light evaporates the dust cloud, dust particles are swept out away from the cloud, car- ried with the heated gas. Webb has detected a network of thin features tracing this move- ment. The observations have also al- lowed astronomers to investigate how the dust blocks and emits light, and to better understand the multi- dimensional shape of the nebula. Next, astronomers intend to study the spectroscopic data that have been obtained to gain insights into the evolution of the physical and chemical properties of the material observed across the nebula.    T ﺗﺮﻛـــــــــﺰ ﻫـــــــــﺬﻩ اﻟﺼـــــــــﻮرة ﻟﺴـــــــــﺪ ﻢ رأس اﻟـــــــــ ـ ﺤﺼﺎن اﻟﻤﻠﺘﻘﻄـــــــــﺔ ﺑﻮاﺳـــــــــﻄﺔ ـــــــــﺐ ﺗﻠﺴـــــــــ ﻮبﺟـــــــــ ﻤﺲو اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟ ﻮ ﺎﻟﺔ ﻧﺎﺳﺎ ﻋﻠﻰﺟﺰء ﻣﻦ " ﻋـﺮف" ـ اﻟـــــ . ﺤﺼﺎن ﺗـــــﻢ اﻟﺘﻘﺎﻃﻬـــــﺎ ﺎﺳـــــﺘﺨﺪام ﺟﻬـــــﺎز ﻣـــــ ي ) أداة اﻷﺷـﻌﺔ ﺗﺤـﺖ اﻟـ ـ ﻤﺮاء اﻟﻤﺘﻮﺳـﻄﺔ ( و ﻠـﺘﻘﻂ ﺿـــــﻮء اﻷﺷـــــﻌﺔ ﺗﺤـــــﺖ اﻟـــــ ـ ﻤﺮاء اﻟﻤﺘﻮﺳـــــﻄﺔ وﻫـــــﺞ ﻣـــــــــــﻮاد ﻣﺜـــــــــــﻞ اﻟﺴـــــــــــ ﻠﻴ ﺎت اﻟﻤﻐـــــــــــ ة واﻟـــــــــــ ـ ﺠﺰﺌﺎت اﻟﺸــﺒﻴﻬﺔ ﺎﻟﺴــﺨﺎم اﻟــ ــﺪروﻛﺮ ﻮﻧﺎت ﺗﺴــﻤﻰ اﻟﻬ اﻟﻌﻄﺮ ــــﺔ ﻣﺘﻌــــﺪدة اﻟــــ ـ . ﺤﻠﻘﺎت ﻓــــﻲﻫــــﺬﻩ اﻟﺼــــﻮرة ﻤﺜﻞ اﻟﻠﻮن اﻷزرق اﻟﻀﻮء ﺄﻃﻮال ﻣﻮﺟ ﺔ ﺗ ﻠﻎ 5.6 و 7.7 و 10 ﻣ ﻜــــــــــــــﺮون؛ اﻷﺧﻀــــــــــــــﺮ ﻫــــــــــــــﻮ 11،12 و 15 ﻣ ﻜﺮون؛ واﻷ ﻤﺮ 18 و 21 و 25 ] ﻣ ﻜـﺮون NASA, ESA, CSA, Karl Misselt (University of Arizona), Alain Abergel (IAS, CNRS [( ﻟﻘﺪ ﺗﺒﺪدت ﺑﺎﻟﻔﻌ ﻞ ﺳـﺤﺐ اﻟﻐـﺎز ا ﺤﻴﻄـﺔ ﺑﺮأس اﻟﺤﺼﺎن ﻟﻜﻦ اﻟﻌﻤﻮد اﻟﺒﺎر ز ﻣﺼﻨﻮع ﻣﻦ ﻛﺘﻞ ﺳﻤﻴﻜﺔ ﻣﻦ ا ﻮاد وﺑﺎﻟﺘﺎﱄ ﻳﺼـﻌﺐ . ﺗﺂﻛﻠﻪ ﻳﻘﺪر ﻋﻠﻤﺎء اﻟﻔﻠﻚ أن رأس اﻟﺤﺼـﺎن ﻳﺘﺒﻘﻰ ﻟﻪ ﺣﻮاﱄ ﺧﻤﺴﺔ ﻣﻼﻳ ﺳﻨﺔ ﻗﺒﻞ أ ن ﺗﻌﺮض ﻫﺬﻩ اﻟﺼﻮرة ﺛﻼﺛﺔ ﻣﻨﺎﻇﺮﻷﺣﺪ أﻛ اﻷﺟﺴﺎم ﺗﻤ ًا ﻓﻲﺳﻤﺎﺋﻨﺎ، وﻫﻮﺳﺪ ﻢ رأساﻟ ـ . ﺤﺼﺎن ﺗُﻈﻬﺮ اﻟﺼـﻮرة اﻷوﻟــﻰ (ﺴـﺎرًا ) ﺗـﻢ إﺻـﺪارﻫﺎ ﻓـﻲ ﻧــﻮﻓﻤ ، اﻟـ 2023 ، ﺳـﺪ ﻢ رأس اﻟــ ـ ﺤﺼﺎن ﻤــﺎ ﻳُـﺮىﻓـﻲ اﻟﻀـﻮء اﻟ ــﮫ ﻣﺴــﺎﻫﻤﺎت ﻣــﻦ و ﺎﻟــﺔ ﻟﺪ ــﺔ، واﻟــﺬ ــﺪس اﻟﺘــﺎﺑﻊ ﻟﻮ ﺎﻟــﺔ اﻟﻔﻀــﺎء اﻷوروﺑ ﻤﺮــﻲ ﺑﻮاﺳــﻄﺔ ﺗﻠﺴــ ﻮب إﻗﻠ ﻧﺎﺳـــﺎ . ــــﺔ ﺗُﻈﻬـــﺮاﻟﺼـــﻮرة اﻟﺜﺎﻧ ) اﻟﻮﺳـــﻄﻰ ( ﻣﻨﻈـــﺮًا ﻟﺴــــﺪ ﻢ رأس اﻟـــ ـ ﺤﺼﺎن ﻓـــﻲﺿــــﻮء اﻷﺷـــﻌﺔ ﺗﺤـــﺖ ا ﻤــــﺮاء ــﺔ ﻤ ﻠــﺔ وﺣﺴﺎﺳــﺔ ﻋــﺎدة ﻣــﺎ ﻳﺤﺠﺒﻬــﺎ ــﺔ ﻣــﻦ ﺗﻠﺴــ ﻮب ﻫﺎﺑــﻞ اﻟﻔﻀــﺎﺋﻲ ﺗﻜﺸــﻒﻫــﺬﻩ اﻟﺼــﻮرة ﻋــﻦ ﻨ اﻟﻘﺮ ــﺎر اﻟﻐ . ﺗُﻈﻬـــﺮ اﻟﺼــﻮرة اﻟﺜﺎﻟﺜـــﺔ ) ﻋﻠــﻰ اﻟ ﻤـــ ( ﻣﻨﻈــﺮاً ـــﺪاً ﺟﺪ ﻟﺴــﺪ ﻢ رأس اﻟـــ ـ ﺤﺼﺎن ﻣــﻦ أداة ـــﺎم ﻧ ) ـــﺎﻣ ا اﻷﺷـﻌﺔ ﺗﺤــﺖ اﻟــ ـ ـﺔ ﻤﺮاء اﻟﻘﺮ ( ــﺐ اﻟﻔﻀــﺎﺋﻲ اﻟﺘﺎ ﻌــﺔ ﻟﺘﻠﺴـ ﻮبﺟـ ﻤﺲو .] NASA, ESA, CSA, Karl Misselt (University of Arizona), Alain Abergel (IAS, CNRS), Mahdi Zamani The Euclid Consortium, Hubble Heritage Project (STScI, AURA [( ﻳﺘﻔﻜﻚ أﻳﻀ .ﺎً ﺗﺮﻛﺰ ﺻﻮرة ﺗﻠﺴـﻜﻮب وﻳـﺐ اﻟﺠﺪﻳﺪ ة ﻋﲆ اﻟﺤﺎﻓﺔ ا ﻀﻴﺌﺔ ﻟﻠﺠﺰء اﻟﻌﻠﻮي ﻣﻦ ﺑﻨﻴﺔ اﻟﻐﺒﺎر واﻟﻐﺎز ا ﻤﻴﺰة ﻟﻠﺴﺪﻳﻢ . ﺳﺪﻳﻢ رأس ا ﻟﺤﺼﺎن ﻫـﻮ ﻣﻨﻄﻘـﺔ ﺗﻔﻜـﻚ ﺿـﻮﺋﻲ ﻣﻌﺮوﻓـﺔ أو PDR و ﰲ ﻣﺜـﻞ ﻫـﺬه ا ﻨﻄﻘ ﺔ ﻳﺨﻠـﻖ اﻟﻀـ ﻮء ﻓـﻮق اﻟﺒﻨﻔﺴـﺠﻲ اﻟﺼـﺎدر ﻋـﻦ اﻟﻨﺠـﻮم اﻟﺸـﺎﺑﺔ اﻟﻀـﺨﻤﺔ ﻣﻨﻄﻘﺔ داﻓﺌﺔ وﻣﺤﺎﻳﺪة ﰲ اﻟﻐﺎﻟﺐ ﻣﻦ اﻟﻐﺎز واﻟﻐﺒﺎر ﺑ اﻟﻐﺎز ا ﺘﺄﻳﻦ ﺑﺎﻟﻜﺎﻣـﻞ ا ﺤـﻴﻂ ﺑﺎﻟﻨﺠﻮم اﻟﻀـﺨﻤﺔ واﻟﺴـﺤﺐ اﻟﺘـﻲ وﻟـﺪت . ﻓﻴﻬﺎ ﺗﺆﺛﺮ ﻫﺬه اﻷﺷﻌﺔ ﻓـﻮق اﻟﺒﻨﻔﺴـﺠﻴﺔ ﺑﻘﻮة ﻋـﲆ ﻛﻴﻤﻴـﺎء ﻫـﺬه ا ﻨـﺎﻃﻖ وﺗﻌﻤـﻞ ﻛﻤﺼﺪر ﻣﻬﻢ ﻟﻠﺤﺮارة . ﺗﺤﺪث ﻫﺬ ه ا ﻨﺎﻃﻖ ﺣﻴﺚ ﻳﻜﻮن اﻟﻐـﺎز ﺑـ اﻟﻨﺠﻮم ﻛﺜﻴﻔ ﺎً ﺑﺪرﺟﺔ ﻛﺎﻓﻴﺔ ﻟﻴﻈـﻞ ﻣﺤﺎﻳـﺪ اً ﰲ اﻟﻐﺎﻟﺐ وﻟﻜﻨﻪ ﻟﻴﺲ ﻛﺜﻴﻔ ﺎً ﺑﺪرﺟﺔ ﻛﺎﻓﻴـﺔ ﻨﻊ اﺧﱰاق اﻷﺷﻌﺔ ﻓﻮق اﻟﺒﻨﻔﺴـﺠﻴﺔ ﻣـﻦ اﻟﻨﺠﻮم اﻟﻀﺨﻤﺔ . إن اﻟﻀـﻮء ا ﻨﺒﻌـﺚ ﻣـﻦ اﻟ ﻣﻨــﺎﻃﻖ ﺘﻔﻜـﻚ اﻟ ﻀﻮﺋﻲ ﻳﻮﻓﺮ أداة ﻓﺮﻳﺪة ﻟﺪراﺳﺔ اﻟﻌﻤﻠﻴﺎت اﻟﻔﻴﺰﻳﺎﺋﻴﺔ واﻟﻜﻴﻤﻴﺎﺋﻴﺔ اﻟ ﺘﻲ ﺗﺤـﺮك ﺗ ﻄـﻮر ا ﺎدة ﺑـ اﻟﻨﺠـﻮم ﰲ ﻣﺠﺮﺗﻨـﺎ وﰲ ﺟﻤﻴـﻊ أﻧﺤﺎء اﻟﻜﻮن ـ ﻣﻨﺬ اﻟﻌـ ﴫ ا ﺒﻜـﺮ ﻟﺘﻜـﻮﻳﻦ اﻟﻨﺠﻮم اﻟﻨﺸﻂ ﺣﺘﻰ ﻳﻮﻣﻨﺎ ﻫﺬا . اً ﻧﻈﺮ ﻟﻘﺮﺑﻪ وﺷﻜﻠﻪ اﻟﻬﻨﺪﳼ اﻟﻘﺮﻳـﺐ ﻣـﻦ اﻟﺤﺎﻓﺔ ﻳﻌـﺪ ﺳـﺪﻳﻢ رأس اﻟﺤﺼـﺎن ﻫـﺪﻓًﺎ ﻣﺜﺎﻟﻴ ـﺎً ﻟﻌﻠﻤــﺎء اﻟﻔﻠ ـﻚ ﻟﺪراﺳــﺔ اﻟﻬﻴﺎﻛــﻞ اﻟﻔﻴﺰﻳﺎﺋﻴـﺔ ﻟــ PDRs واﻟﺘﻄـﻮر اﻟﺠﺰﻳﺌـﻲ ﻟ ﻠﻐـﺎز واﻟﻐﺒـﺎر داﺧـﻞ ﺑﻴﺌـﺎﺗﻬﻢ اﻟﺨﺎﺻـﺔ وا ﻨﺎﻃﻖ اﻻﻧﺘﻘﺎﻟﻴﺔ ﺑﻴﻨﻬﻢ . اﻟﻔﻴﺰﻳﺎﺋﻴﺔ ﻨﺎﻃﻖ اﻟﺘﻔﻜﻚ اﻟﻀﻮﺋﻲ واﻟﺘﻄﻮر اﻟ ﺠﺰﻳﺌـﻲ ﻟﻠﻐ ـﺎز واﻟﻐﺒ ـﺎر داﺧـﻞ ﺑﻴﺌﺎﺗﻬ ـ ﺎ اﻟﺨﺎﺻﺔ وا ﻨﺎﻃﻖ اﻻﻧﺘﻘﺎﻟﻴﺔ ﺑﻴﻨﻬـ ﺎ وﺗﻌﺘـﱪ ﻣﻦ أﻓﻀﻞ ﻣﻨﺎﻃﻖ اﻟﺴﻤﺎء ﻟﺪراﺳـﺔ ﻛﻴﻔﻴـﺔ ﺗﻔﺎﻋﻞ اﻹﺷﻌﺎع ﻣﻊ ا ﺎدة ﺑ اﻟﻨﺠﻮم . ﺑﻔﻀﻞ أ ﺟﻬﺰة ﺗﻠﺴﻜﻮب وﻳﺐ اﻟﺘـﻲ ﺗﺸـﻤﻞ ﻛـﺎﻣ ا ﻣـ ي ) ﻟﻸﺷـﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء ا ﺘﻮﺳﻄﺔ ( وﻛﺎﻣ ا ﻧ ﻛﺎم ) ﻟﻸﺷﻌﺔ ﺗﺤـﺖ اﻟﺤﻤﺮاء اﻟﻘﺮﻳﺒﺔ ( ﻛﺸـﻒ ﻓﺮﻳـﻖ دوﱄ ﻣـﻦ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻷول ﻣﺮة ﻋﻦ اﻟﻬﻴﺎﻛﻞ اﻟﺼﻐ ة اﻟﺤﺠﻢ ﻟﻠﺤﺎﻓﺔ ا ﻀﻴﺌﺔ ﻟﺮأس اﻟﺤﺼﺎن . ﻋﻨﺪﻣﺎ ﻳﺒﺨﺮ ﺿﻮء اﻷ ﺷﻌﺔ ﻓﻮق اﻟﺒﻨﻔﺴﺠﻴﺔ ﺳﺤﺎﺑﺔ اﻟﻐﺒﺎر ﻳ ﺘﻢ ﻣﺴـﺢ ﺟﺰﻳﺌـﺎت اﻟﻐﺒـﺎر وﻗﺬﻓﻬﺎ ﺑﻌﻴـﺪاً ﻋـﻦ اﻟﺴـﺤﺎﺑﺔ وﺑﻌـﺪ ذﻟـﻚ ﻳﺤﻤﻠﻬﺎ اﻟﻐﺎز اﻟﺴﺎﺧﻦ . اﻛﺘﺸﻒ ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ ﺷﺒﻜﺔ ﻣـﻦ اﻷﺷﻜﺎل اﻟﺮﻓﻴﻌﺔ اﻟﺘﻲ ﺗﺘﺘﺒﻊ ﻫﺬه اﻟﺤﺮﻛـﺔ . ﻟ ﻘﺪ أﺗﺎﺣﺖ اﻷرﺻـﺎد أﻳﻀـ ﺎً ﻟﻌﻠﻤـﺎء اﻟﻔﻠـﻚ اﺳﺘﻜﺸﺎف ﻛﻴﻔﻴـﺔ ﺣﺠـﺐ اﻟﻐﺒـﺎر ﻟﻠﻀـﻮء وإﺻـﺪاره وﻓﻬـﻢ اﻟﺸـﻜﻞ ﻣﺘﻌـﺪد اﻷﺑﻌـﺎد ﻟﻠﺴﺪﻳﻢ ﺑﺸﻜ ﻞ أﻓﻀﻞ . ﺑﻌﺪ ذﻟﻚ ﻳﻌﺘﺰم ﻋﻠﻤﺎء اﻟﻔﻠﻚ اﻟﻘﻴﺎم ﺑ ﺪراﺳﺔ اﻟﺒﻴﺎﻧﺎت اﻟﻄﻴﻔﻴﺔ اﻟﺘﻲ ﺗﻢ اﻟﺤﺼـﻮل ﻋﻠﻴﻬـﺎ ﻣﻦ ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ ﻟﻠﺤﺼـﻮل ﻋـﲆ ﻧﻈــﺮة واﺿــﺤﺔ ﺑﻬــﺪف ﻓﻬــﻢ ﺗﻄــﻮر اﻟﺨﺼﺎﺋﺺ اﻟﻔﻴﺰﻳﺎﺋﻴـﺔ واﻟﻜﻴﻤﻴﺎﺋﻴـﺔ ﻟ ﺘﻠـﻚ ا ﺎدة ا ﺮﺻﻮدة ﻋﱪ اﻟﺴﺪﻳﻢ . - ﻳﻮﻟﻴﻮ ﺃﻏﺴﻄﺲ 2 0 2 4