Free Astronomy Magazine July-August 2025 ARABIC VERSION

Unveiling the birth secrets of HW2 in Cepheus A byNationalRadioAstronomyObservatory singtheU.S.NationalScience FoundationNationalRadioAstronomy Observatory’s (NSFNRAO)U.S.NationalScienceFound a- tion Very Large Array (NSF VLA), as- tronomershaverevealedforthefirst timethehugeflowofgasneara massive star in the making which al- lows its rapid growth. By observing the young star HW2 in Cepheus A,located 2300 light years from Earth, researchers have resolved the struc- ture and dynamics of an accretiondisk feeding material to this massive star.Thisfindingshedslightona centralquestioninastrophysics:how do massive stars, which often endtheir lives as supernovae, accumu- late their immense mass? Cepheus A is the second closest site of massive starformationtoEarth,makingitan ideal laboratory for studying these challenging processes. The research teamusedammonia(NH 3 ),amole- cule commonly found in interstellar gas clouds and widely used industri- ally on Earth, as a tracer to map the gas dynamics around the star. Observations revealed a dense ring of hot ammonia gas spanning radii of 200 to 700 astronomical units (AU) around HW2. This structure was identified as part of an accre- tion disk—a key feature in star for- mation theories. Thestudyfoundthatgaswithinthis disk is both collapsing inward and rotatingaroundtheyoungstar.Re- markably,theinfallrateofmaterial onto HW2 was measured at two thousandths of a solar mass per year—one of the highest rates ever observedforaformingmassivestar. These findings confirm that accre- tiondiskscansustainsuchextreme mass transfer rates even when the centralstarhasalreadygrownto16 times the mass of our Sun. U ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 16 ﻛﺸﻒ أﺳﺮار HW2 ﻓﻲ اﻟﻨﻈﺎم اﻟﻨ ﻤﻲ اﻟﻤﻠﺘﻬﺐ A : ﻘﻠﻢ ﻟﻌﻠﻢ اﻟﻔﻠﻚ اﻟﺮادﻳﻮي اﻟﻤﺮﺻﺪ اﻟﻮﻃ ﺎﺳـﺘﺨﺪام ﻣﺼﻔﻮﻓﺔ ا ﺮاﺻﺪ اﻟﻜﺒ ة ﺟـﺪ اً اﻟﺘﺎﺑﻌﺔ ﻟﻠﻤﺆﺳﺴﺔ اﻟﻮﻃﻨﻴﺔ ﻟﻠﻌﻠﻮم اﻷﻣﺮﻳﻜﻴﺔ اﻟﺘﺎﺑﻌﺔ ﻟﻠﻤﺮﺻﺪ اﻟﻮﻃﻨﻲ ﻟﻌﻠﻢ اﻟﻔﻠﻚ اﻟﺮا دﻳﻮي ﻛﺸﻒ ﻋﻠﻤﺎء اﻟﻔﻠـﻚ ﻷول ﻣـﺮة ﻋـﻦ اﻟﺘـﺪﻓﻖ اﻟﻬﺎﺋﻞ ﻟﻠﻐﺎز ﰲ ﻧﺠﻢ ﺿﺨﻢ ﻗﻴﺪ اﻟﺘﻜﻮن، ﻣﻤـﺎ ﻳﺴﻤﺢ ﺑﻨ ﻤﻮه اﻟﴪـﻳﻊ . ﻣـﻦ ﺧـﻼل ﻣﺮاﻗﺒـﺔ اﻟ ـﻨﺠﻢ اﻟﺸــﺎب HW2 ﰲ اﻟﻨﻈ ـﺎم اﻟﻨﺠﻤــﻲ ا ﻠﺘﻬـﺐ اﻟﻮاﻗـﻊ ﻋـﲆ ﻣﺴـﺎﻓﺔ 2300 ﺳـﻨﺔ ﺿـﻮﺋﻴﺔ ﻣـﻦ اﻷرض ﺗﻤﻜـﻦ اﻟﺒـﺎﺣﺜﻮن ﻣـﻦ ﺗﺤﺪﻳﺪ ﺑﻨﻴﺔ ودﻳﻨﺎﻣﻴﻜﻴﺎت ﻗﺮص اﻟﱰاﻛﻢ اﻟﺬي ﻳﻐﺬي ﻫﺬا اﻟﻨﺠﻢ اﻟﻀﺨﻢ ﺑﺎ ﻮاد . ﺗُﻠﻘﻲ ﻫﺬه اﻟﻨﺘﻴﺠﺔ اﻟﻀﻮء ﻋﲆ ﺳﺆال ﻣﺤﻮري ﰲ اﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴـﺔ : ﻛﻴـﻒ ﺗُـﺮاﻛﻢ اﻟﻨﺠـﻮم اﻟﻀـﺨﻤﺔ، اﻟﺘـﻲ ﻏﺎﻟﺒًـ ﺎ ﻣـﺎ ﺗُﻨﻬـﻲ ﺣﻴﺎﺗﻬـﺎ ﻛﻤﺴﺘﻌﺮات ﻋﻈﻤـﻰ ﻛﺘﻠﺘﻬـﺎ اﻟﻬﺎﺋﻠـﺔ؟ ﻳُﻌـﺪ ﺳﻴﻔﻴﻮس أ ﺛﺎﻧﻲ أﻗﺮب ﻣﻮﻗﻊ ﻟﺘﻜﻮﻳﻦ اﻟﻨﺠﻮم اﻟﻀـﺨﻤﺔ إﱃ اﻷرض، ﻣﻤـﺎ ﻳﺠﻌﻠـﻪ ﻣﺨﺘ ـﱪًا ﻣﺜﺎﻟﻴًـﺎ ﻟﺪراﺳـﺔ ﻫـﺬه اﻟﻌﻤﻠﻴـﺎت اﻟﺼـﻌﺒﺔ . اﺳﺘﺨﺪم ﻓﺮﻳـﻖ اﻟﺒﺤـﺚ اﻷﻣﻮﻧﻴـﺎ - - ﺟـﺰيء أﻣﻮﻧﻴﺎ ا ﻮﺟـﻮد ﻋـﺎدةً ﰲ ﺳُـﺤﺐ اﻟﻐـﺎز ﺑـ اﻟﻨﺠﻮم وا ُﺴﺘﺨﺪم ﻋﲆ ﻧﻄﺎق واﺳﻊ ﺻﻨﺎﻋﻴًﺎ اﻟﻨﺠﻮم وا ُﺴﺘﺨﺪم ﻋﲆ ﻧﻄﺎق واﺳﻊ ﺻﻨﺎﻋﻴﺎً ﻋ ــﲆ اﻷرض ﻛﻤُﺘﺘﺒ ــﻊ ﻟﺮﺳــﻢ ﺧﺮﻳﻄـــﺔ ﻟﺪﻳﻨﺎﻣﻴﻜﻴﺎت اﻟﻐﺎز ﺣﻮل اﻟﻨﺠﻢ . ﻛﺸﻔﺖ ا ﻼﺣﻈﺎت ﻋﻦ ﺣ ﻠﻘﺔ ﻛﺜﻴﻔﺔ ﻣﻦ ﻏﺎز اﻷﻣﻮﻧﻴﺎ اﻟﺴﺎﺧﻦ ﺗﻤﺘﺪ ﻋـﲆ أﻧﺼـﺎف أﻗﻄـﺎر ﺗﱰاوح ﺑ 200 و 700 وﺣـﺪة ﻓﻠﻜﻴـﺔ ﺣـﻮل اﻟﻨﺠﻢ HW2 . ﺪدﺣ ﻫﺬا اﻟﻬﻴﻜـﻞ ﻛﺠـﺰء ﻣـﻦ ﻗــﺮص ﺗﺮاﻛﻤ ـﻲ وﻫ ـﻲ ﺳـﻤﺔ رﺋﻴﺴـﻴﺔ ﰲ ﻧﻈﺮﻳﺎت ﺗﻜﻮّن اﻟﻨﺠﻮم . ﻟﻘﺪ وﺟﺪت اﻟﺪراﺳﺔ أن اﻟﻐﺎز ا ﻮﺟـﻮد داﺧـﻞ ﻫﺬا اﻟﻘﺮص ﻳﻨﻬﺎر إﱃ اﻟـﺪاﺧﻞ وﻳـﺪور ﺣـﻮل اﻟﻨﺠﻢ اﻟﺸﺎب . ﻟﻌﻞ ﻣﻦ اﻟﻼﻓﺖ ﻟﻠﻨﻈﺮ أن ﻣﻌﺪل ﺳﻘﻮط ا ﻮاد ﻋﲆ HW2 ﻗﺪ ﻗُـ ﻴﺲ ﻋﻨـﺪ أﻟﻔـ ﻣـﻦ ﻛﺘﻠـﺔ اﻟﺸﻤﺲ ﺳﻨﻮﻳ ﺎً وﻫﻮ أﺣﺪ أﻋﲆ ا ﻌﺪﻻت اﻟﺘـﻲ ر ﺻﺪت ﻋﲆ اﻹﻃﻼق ﻟﺘﻜﻮﻳﻦ ﻧﺠﻢ ﺿﺨﻢ . ﺗﺆﻛﺪ ﻫﺬه اﻟﻨﺘﺎﺋﺞ أن أﻗﺮاص اﻟﱰاﻛﻢ ﻳﻤﻜﻦ أن ﺗﺤﺎﻓﻆ ﻋﲆ ﻣﻌﺪﻻت ﻧﻘﻞ ﻛﺘﻠﺔ ﻣﺘﻄﺮﻓﺔ ﻛﻬﺬه ﺣﺘﻰ ﻋﻨﺪﻣﺎ ﺗﻜﻮن ﻛﺘﻠﺔ اﻟـﻨﺠﻢ ا ﺮﻛـﺰي ﻗـﺪ ﻧﻤﺖ ﺑﺎﻟﻔﻌﻞ إﱃ 16 ﺿﻌﻒ ﻛﺘﻠﺔ اﻟﺸﻤﺲ . ﻳﻮﻟﻴﻮ - ﺃﻏﺴﻄﺲ 2 0 2 5