Free Astronomy Magazine May-June 2023 ARABIC VERSION

  The elusive prelude to a supernova by NASA/ESA/CSA Leah Ramsay Christine Pulliam he rare sight of a Wolf-Rayet star – among the most lumi- nous, most massive, and most briefly-detectable stars known – was one of the first observations made by NASA’s James Webb Space Tele- scope in June 2022. Webb shows the star, WR 124, in unprecedented de- tail with its powerful infrared instru- ments. The star is 15,000 light-years away in the constellation Sagitta. Massive stars race through their life- cycles, and only some of them go through a brief Wolf-Rayet phase before going supernova, making Webb’s detailed observations of this rare phase valuable to astronomers. Wolf-Rayet stars are in the process of casting off their outer layers, re- sulting in their characteristic halos of gas and dust. The star WR 124 is 30 times the mass of the Sun and has shed 10 Suns’ worth of material—so far. As the ejected gas moves away from the star and cools, cosmic dust forms and glows in the infrared light detectable by Webb. The origin of cosmic dust that can survive a supernova blast and con- tribute to the universe’s overall “dust budget” is of great interest to astronomers for multiple reasons. Dust is integral to the workings of the universe: It shelters forming stars, gathers together to help form planets, and serves as a platform for molecules to form and clump to- gether—including the building blocks of life on Earth. Despite the many essential roles that dust plays, there is still more dust in the uni- verse than astronomers’ current dust-formation theories can explain. The universe is operating with a dust budget surplus. Webb opens up new possibilities for studying details in cosmic dust, which is best observed in infrared ٤٦ ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ اﻟﻤﻘﺪﻣﺔ اﻟﻐﺎﻣﻀﺔ ﻠﻟ اﻷ ﻤﺴﺘﻌﺮ ﻋﻈﻢ : ﻘﻠﻢ ﻟ ﺎ راﻣﺰي ﺑﻮﻟ ﺎم و ﻛﺮ ﺘﺴ تو ﺎﻻ اﻟﻔﻀﺎء ﻧﺎﺳﺎ و اﻷوروﺑ ﺔ واﻟﻜﻨﺪ ﺔ ــــ ﻛﺎن ا ﺸﻬﺪ اﻟﻨﺎدر ﻟﻨﺠﻢ ووﻟـﻒ راﻳـﺖ ﻣﻦ ﺑ أﻛﺜﺮ اﻟﻨﺠﻮم ﻌﺎﻧًـﺎ وﻛﺘﻠـﺔ واﻷﻛﺜـﺮ ﻗﺎﺑﻠﻴﺔ ﻟﻼﻛﺘﺸﺎف ﻟﻔﱰة وﺟﻴﺰة أﺣﺪ اﻷرﺻﺎد اﻷوﱃ اﻟﺘﻲ ﻗﺎم ﺑﻬﺎ ﺗﻠﺴﻜﻮب ﺟـﻴﻤﺲ وﻳـﺐ اﻟﻔﻀ ـﺎﺋﻲ اﻟﺘــﺎﺑﻊ ﻟﻨﺎﺳ ـﺎ ﰲ ﻳﻮﻧﻴــﻮ ٢٠٢٢ ﻳﻌـﺮض ﺗﻠﺴـﻜﻮب وﻳـﺐ اﻟـﻨﺠﻢ WR 124 ﺑﺘﻔﺎﺻﻴﻞ ﻏ ﻣﺴﺒﻮﻗﺔ ﺑﺎﺟﻬﺰة اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤ ﺮاء اﻟﻘﻮﻳﺔ . ﻳﺒﻌﺪ اﻟـﻨﺠﻢ ١٥٠٠٠ ﺳـﻨﺔ ﺿﻮﺋﻴﺔ ﰲ ﻛﻮﻛﺒ ﺔ اﻟﺴﻬﻢ . ﺗﺘﺴـﺎﺑﻖ اﻟﻨﺠـﻮم اﻟﻀﺨﻤﺔ ﺧﻼل دورات ﺣﻴﺎﺗﻬﺎ وﺑﻌﻀﻬﺎ ﻓﻘﻂ ﻳﻤﺮ ﺑﻤﺮﺣﻠﺔ وﺟﻴﺰة ﻣﻦ ) ( راﻳﺖ - ووﻟﻒ ﻗﺒﻞ أن ﻳﺘﺤﻮل إﱃ ﻣﺴـﺘﻌﺮ أﻋﻈـﻢ ، ﻣﻤـﺎ ﻳﺠﻌـﻞ ارﺻـﺎد ﺗﻠﺴـﻜﻮب وﻳـﺐ اﻟﺘﻔﺼـﻴﻠﻴﺔ ﻟﻬـﺬه ا ﺮﺣﻠﺔ اﻟﻨـﺎدرة ذات ﻗﻴﻤـﺔ ﻟﻌﻠﻤـﺎء اﻟﻔﻠـﻚ . ﻧﺠﻮم وو ﻟﻒ راﻳـﺖ ﰲ ﻃـﻮر اﻟـﺘﺨﻠﺺ ﻣـﻦ ﻃﺒﻘﺎﺗﻬﺎ اﻟﺨﺎرﺟﻴﺔ ﻣﻤﺎ ﻳﻨـﺘﺞ ﻋﻨـﻪ ﻫـﺎﻻت ﻣﻤﻴﺰة ﻣﻦ اﻟﻐﺎز واﻟﻐﺒﺎر . ﺗﺒﻠﻎ ﻛﺘﻠـﺔ اﻟـﻨﺠﻢ WR 124 ﺛﻼﺛ ﺿﻌﻒ ﻛﺘﻠﺔ اﻟﺸـﻤﺲ وﻗـﺪ ﻗﺬف ﺑﻤﺎ ﻳﻌﺎدل ١٠ ﺷﻤﻮس ﻣﻦ ا ﻮاد ﺣﺘـﻰ اﻵن . ﻋﻨﺪﻣﺎ ﻳﺘﺤﺮك اﻟﻐﺎز ا ﻘﺬوف ﺑﻌﻴﺪًا ﻋـﻦ ــ اﻟﻨﺠﻢ و ﻳﱪد ﻳﺘﺸـﻜﻞ اﻟﻐﺒـﺎر اﻟﻜـﻮﻧﻲ اﻟـﺬي ﻳ ﺘﻮﻫﺞ وﻳﻤﻜﻦ اﻛﺘﺸـﺎﻓﻪ ﰲ ﺿـﻮء اﻷﺷـﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ﺑﻮاﺳﻄﺔ ﺗﻠﺴـﻜﻮب وﻳـﺐ إن . أﺻﻞ اﻟﻐﺒﺎر اﻟﻜﻮﻧﻲ اﻟﺬي ﻳﻤﻜﻨﻪ اﻟﺼـﻤﻮد ﰲ وﺟﻪ اﻧﻔﺠـﺎر ﻣﺴـﺘﻌﺮ أﻋﻈـﻢ وﻳﺴـﺎﻫﻢ ﰲ " ﻣﻴﺰاﻧﻴﺔ اﻟﻐﺒﺎر اﻹ " ﺟﻤﺎﻟﻴﺔ ﻟﻠﻜـﻮن ﻳﺤﻈـﻰ ﺑﺎﻫﺘﻤﺎم ﻛﺒـ ﻣـﻦ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﻷﺳـﺒﺎب . ﻣﺘﻌﺪدة ﻳﻌﺪ اﻟﻐﺒﺎر ﺟﺰءًا ﻻ ﻳﺘﺠﺰأ ﻣﻦ أﻋﻤﺎل اﻟ : ﻜﻮن ﻓﻬﻮ ﻳﺤﻤﻲ ﺗﻜﻮﻳﻦ اﻟﻨﺠﻮم وﻳﺘﺠﻤـﻊ ﻣﻌًﺎ ﻟﻠﻤﺴﺎﻋﺪة ﰲ ﺗﻜﻮﻳﻦ اﻟﻜﻮاﻛـﺐ وﻳﻌﻤـﻞ ﻛﻤﻨﺼﺔ ﻟﻠﺠﺰﻳﺌﺎت ﻟﺘﺘﺸﻜﻞ وﺗﺘﺠﻤﻊ ﻣﻌًﺎ ﺑﻤﺎ ﰲ ذﻟﻚ اﻟﻠﺒﻨﺎت اﻷﺳﺎﺳﻴﺔ ﻟﻠﺤﻴﺎة ﻋﲆ اﻷرض . ﺑ ﺎﻟﺮﻏﻢ ﻣﻦ اﻷدوار اﻷﺳﺎﺳﻴﺔ اﻟﻌﺪﻳـﺪة اﻟﺘـﻲ ﻳﻠﻌﺒﻬﺎ اﻟﻐﺒﺎر ، ﻻ ﻳﺰال ﻫﻨﺎك ﻏﺒﺎر ﰲ اﻟﻜـﻮن أﻛﺜﺮ ﻣﻤﺎ ﻳﻤﻜﻦ أن ﺗﻔﴪ ه ﻧﻈﺮﻳـﺎت ﺗﻜـﻮﻳﻦ اﻟﻐﺒﺎر اﻟﺤﺎﻟﻴﺔ ﻟﻌﻠﻤﺎء اﻟﻔﻠﻚ ان . اﻟﻜﻮن ﻳﻌﻤﻞ ﺑﻔﺎﺋﺾ ﻣﻴﺰاﻧﻴﺔ اﻟﻐﺒﺎر وﺗﻠﺴﻜﻮب وﻳﺐ ﻳﻔﺘﺢ إﻣﻜﺎﻧﻴﺎت ﺟﺪﻳﺪة ﻟﺪراﺳﺔ اﻟﺘﻔﺎﺻﻴﻞ ﰲ اﻟﻐﺒﺎر اﻟﻜﻮﻧﻲ واﻟﺘﻲ ﻳﻤﻜﻦ رﺻﺪﻫﺎ ﺑﺸﻜﻞ أﻓﻀﻞ ﰲ أﻃﻮال ﻣﻮﺟﺎت اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ﻟﻠﻀﻮء ـ - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2023 ﻟﻘﺪ