Free Astronomy Magazine July-August 2025 ARABIC VERSION

“Ourobservationsprovidedirectev- idence that massive stars can form through disk-mediated accretion up totensofsolarmasses,” saidDr.Al- berto Sanna, lead author of the study. “The NSF VLA’s unparalleled radio sensitivity allowed us to re- solvefeaturesonscalesontheorder of 100 AU only, offering unprece- dented insights into this process.” Theteamalsocomparedtheirobser- vations with state-of-the-art simu- lations of massive star formation. “The results aligned closely with theoretical predictions, showingthat ammonia gas near HW2 is col- lapsing almost at free-fall speeds while rotating at sub-Keplerian ve- locities—a balance dictated by grav- ity and centrifugal forces,” said Prof. André Oliva, who performed the detailed simulations. Interestingly, the study uncovered asymmetriesinthedisk’sstructure andturbulence,suggestingthatex- ternal streams of gas—known as “streamers”—may be delivering fresh material to one side of the disk.Suchstreamershavebeenob- servedinotherstar-formingregions andmayplayacrucialroleinreplen- ishing accretion disks around mas- sive stars. This discovery resolves decades of debate over whether HW2,andprotostarsalike,canform accretiondisksabletosustaintheir rapidgrowth.Italsoreinforcesthe idea that similar physical mecha- nismsgovernstarformationacrossa wide range of stellar masses. “HW2 has been known for more than 40 years by now and still in- spires new generations of as- tronomers,” said Prof. José María Torrelles, who conducted some pivotal observations of HW2 in the late ‘90s. The findings were made possiblebyhigh-sensitivityNSFVLA observationsconductedatcentime- ter wavelengths in 2019. The re- searcherstargetedspecificammonia transitionsthatareexcitedattem- peratures above 100 Kelvin, en- abling them to trace dense and warm gas near HW2. “These results highlight the power ofradiointerferometrytoprobethe hidden processes behind the forma- tion of the most influential objects inourGalaxy,− saidDr.ToddHunter of the NRAO, , − and, in ten years, the next upgraded version of theVLA will make it possible to study circum-stellar ammonia at scales of our Solar system.” This work not only advances our un- derstanding of how massive stars form but also has implications for broader questions about galaxy evo- lution and chemical enrichment in the universe. Massive stars play piv- otal roles as cosmic engines, driving winds and explosions that seed galaxies withheavyelements.     JULY-AUGUST2025 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 17 ﻗﺎل اﻟﺪﻛﺘﻮر أﻟﱪﺗﻮ ﺳـﺎﻧﺎ ا ﺆﻟـﻒ اﻟﺮﺋﻴـ ﴘ ـ ﻟﻠﺪراﺳﺔ " : ﺗُﻘﺪم أرﺻﺎدﻧﺎ دﻟﻴﻼً ﻣﺒـﺎﴍاً ﻋـﲆ أن اﻟﻨﺠﻮم اﻟﻀﺨﻤﺔ ﻳﻤﻜـﻦ أن ﺗﺘﺸـﻜﻞ ﻣـﻦ ﺧـﻼل ﺗـﺮاﻛﻢ ﺑﻮﺳـﺎﻃﺔ اﻟﻘـﺮص ﻳﺼـﻞ إﱃ ﻋﴩات اﻵﻻف ﻣﻦ اﻷﺳﻄﻮاﻧﺎت اﻟﺸﻤﺴـﻴﺔ ." وأﺿ ـﺎف " : ﻟﻘــﺪ أﺗﺎﺣــﺖ ﻟﻨــﺎ اﻟﺤﺴﺎﺳــﻴﺔ اﻟﺮادﻳﻮﻳﺔ ﺮﺻﺪ ا ﺼﻔﻮﻓﺔ اﻟﻜﺒ ة ﺟﺪاَ اﻟﺘﺎﺑﻊ ﺆﺳﺴﺔ اﻟﻌﻠﻮم اﻟﻮﻃﻨﻴـﺔ ﺗﺤﺪﻳـﺪ ﺧﺼـﺎﺋﺺ ﻋﲆ ﻧﻄﺎﻗﺎت ﺗﺼﻞ إﱃ 100 وﺣﺪة ﻓﻠﻜﻴﺔ ﻓﻘﻂ ﻣﻤﺎ ﻳﻮﻓﺮ رؤى ﻏ ﻣﺴﺒﻮﻗﺔ ﰲ ﻫﺬه اﻟﻌﻤﻠﻴﺔ . ﻛﻤﺎ ﻗﺎرن اﻟﻔ ﺮﻳﻖ أرﺻﺎدﻫﻢ ﺑﺄﺣﺪث ﻋﻤﻠﻴﺎت ا ﺤﺎﻛﺎة ﻟﺘﻜﻮﻳﻦ اﻟﻨﺠﻮم اﻟﻀﺨﻤﺔ . ﻗﺎل اﻟﱪوﻓﻴﺴﻮر أﻧﺪرﻳﻪ أوﻟﻴﻔﺎ اﻟـﺬي أﺟـﺮى ﻋﻤﻠﻴ ـﺎت ا ﺤﺎﻛ ـﺎة اﻟﺘﻔﺼ ـﻴﻠﻴﺔ " : ﺗﻮاﻓﻘ ـﺖ اﻟﻨﺘﺎﺋ ﺞ ﺑﺸﻜﻞ وﺛﻴﻖ ﻣﻊ اﻟﺘﻮﻗﻌـﺎت اﻟﻨﻈﺮﻳـﺔ ﺣﻴﺚ أﻇﻬﺮت أن ﻏﺎز اﻷﻣﻮﻧﻴـﺎ ﺑـﺎﻟﻘﺮب ﻣـﻦ اﻟﻨﺠﻢ HW2 ﻳﻨﻬﺎر ﺑـ ـ ﴪﻋﺎت ﺗﻜـﺎد ﺗ ﻌـﺎدل ﴎﻋﺔ اﻟﺴﻘﻮط اﻟﺤﺮ أﺛﻨﺎء دوراﻧﻪ ﺑ ـ ﴪﻋﺎت دون ﴎﻋﺔ ﻛﻴﺒﻠﺮ وﻫﻮ ﺗﻮازن ﺗﻔﺮﺿﻪ ﻗـﻮى اﻟﺠﺎذﺑﻴﺔ واﻟﻄﺮد ا ﺮﻛﺰي ." وﻣﻦ ا ﺜ ﻟﻼﻫﺘﻤﺎم أن اﻟﺪراﺳﺔ ﻛﺸﻔﺖ ﻋـﻦ ﻋﺪم ﺗﻨﺎﺳﻖ ﰲ ﺑﻨﻴﺔ اﻟﻘﺮص واﺿﻄﺮاﺑﺎ ﺗﻪ ﻣﻤﺎ ﻳﺸ إﱃ أن ﺗﻴﺎرات ﺧﺎرﺟﻴﺔ ﻣﻦ اﻟﻐﺎز ﺗُﻌﺮف " ﺑﺎﺳﻢ اﻟﺘﺪﻓﻘﺎت ﻮﺻﻞ ﻗﺪ ﺗ " ﻣﻮاد ﺟﺪﻳـﺪة إﱃ أﺣﺪ ﺟﺎﻧﺒﻲ اﻟﻘﺮص وﻗﺪ ﻟﻮﺣﻈﺖ ﻣﺜـﻞ ﻫـﺬه اﻟﺘﺪﻓ ﻘﺎت ﰲ ﻣﻨﺎﻃﻖ أﺧﺮى ﻟﺘﻜـﻮﻳﻦ اﻟﻨﺠـﻮم وﻗﺪ ﺗﻠﻌـﺐ دور اً ﺎً ﺣﺎﺳـﻤ ﰲ ﺗﺠﺪﻳـﺪ أﻗـﺮاص اﻟﱰاﻛﻢ ﺣﻮل اﻟﻨﺠﻮم اﻟﻀﺨﻤﺔ . ﻳُﻨﻬﻲ ﻫﺬا اﻻﻛﺘﺸﺎف ﻋﻘﻮد اً ﻣﻦ اﻟﺠ ﺪل ﺣـﻮل ﻣﺎ إذا ﻛﺎن ﺑﺈﻣﻜـﺎن اﻟـﻨﺠﻢ HW2 واﻟﻨﺠـﻮم اﻷوﻟﻴﺔ ا ﺸﺎﺑﻬﺔ ﺗﻜﻮﻳﻦ أﻗﺮاص ﺗﺮاﻛﻢ ﻗـﺎدرة ﻋﲆ اﻟﺤﻔﺎظ ﻋﲆ ﻧﻤﻮﻫﺎ اﻟﴪﻳﻊ . ﻛﻤﺎ أﻧﻪ ﻳ ﻌﺰز ﻓﻜﺮة أن آﻟﻴﺎت ﻓﻴﺰﻳﺎﺋﻴﺔ ﻣﻤﺎﺛﻠﺔ ﺗﺤﻜﻢ ﺗﻜﻮﻳﻦ اﻟﻨﺠﻮم ﻋﱪ ﻣﺠﻤﻮﻋﺔ واﺳـﻌﺔ ﻣﻦ اﻟﻜﺘﻞ اﻟﻨﺠﻤﻴﺔ . ﻗﺎل اﻟﱪوﻓﻴﺴﻮر ﺧﻮﺳـﻴﻪ ﻣﺎرﻳـﺎ ﺗـﻮرﻳﻠﻴﺲ اﻟﺬي أﺟﺮى ﺑﻌﺾ اﻷرﺻﺎد ا ﺤﻮرﻳـﺔ ﻟ ﻠـﻨﺠﻢ HW2 ﰲ أواﺧـﺮ اﻟﺘﺴـﻌﻴﻨﻴﺎت " : ﻟﻘـﺪ ﻋـ ﺮف اﻟﻨﺠﻢ HW2 ﻣﻨﺬ أﻛﺜﺮ ﻣﻦ 40 ﺎً ﻋﺎﻣ وﻻ ﻳـﺰال ﻳُﻠﻬـﻢ أﺟﻴـﺎﻻً ﺟﺪﻳـﺪة ﻣـﻦ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ." أﺻﺒﺤﺖ ﻫﺬه اﻟﻨﺘﺎﺋﺞ ﻣﻤﻜﻨﺔ ﺑﻔﻀﻞ ﻋﻤﻠﻴﺎت رﺻﺪ ﻋﺎﻟﻴﺔ اﻟﺤﺴﺎﺳـﻴﺔ ﺑﺎﺳـﺘﺨﺪام ﻣﺮﺻـﺪ اﻟﺘﺪاﺧﻞ اﻟﺮادﻳﻮي اﻟﻜﺒـ ﺟـﺪا أُﺟﺮﻳـﺖ ﻋﻨـﺪ أﻃـﻮال ﻣﻮﺟﻴـ ﺔ ﺳـﻨﺘﻴﻤﱰﻳﺔ ﰲ ﻋـﺎم 2019 . اﺳﺘﻬﺪف اﻟﺒﺎﺣﺜﻮن اﻧﺘﻘﺎﻻت ﻣﺤﺪدة ﻟﻸﻣﻮﻧﻴﺎ ﺗُﺜﺎر ﻋﻨﺪ درﺟﺎت ﺣﺮارة أﻋﲆ ﻣﻦ 100 ﻔـﻦ ﻛﻠ ﻣﻤﺎ ﻣﻜ ﻨﻬﻢ ﻣﻦ ﺗﺘﺒﻊ اﻟﻐﺎز اﻟﻜﺜﻴﻒ واﻟـﺪاﻓﺊ ﺑﺎﻟﻘﺮب ﻣﻦ اﻟﻨﺠﻢ HW2 . ﺗ ﺴﻠﻂ ﻫﺬه اﻟﻨﺘﺎﺋﺞ اﻟﻀﻮء ﻋﲆ ﻗـﻮة ﻗﻴـﺎس اﻟﺘﺪاﺧﻞ اﻟﺮادﻳـﻮي ﰲ اﺳﺘﻜﺸـﺎف اﻟﻌﻤﻠﻴـﺎت اﻟﺨﻔﻴ ﺔ وراء ﺗﻜﻮﻳﻦ أﻛﺜﺮ اﻷﺟﺴـﺎم ﺗـﺄﺛ ﰲ اً ﻣﺠﺮﺗﻨﺎ ﻫﺬا ﻣﺎ ﻗﺎﻟﻪ اﻟﺪﻛﺘﻮر ﺗﻮد ﻫـﺎﻧﱰ ﻣـﻦ ا ﺮﺻﺪ اﻟﻮﻃﻨﻲ ﻟﻌﻠﻢ اﻟﻔﻠﻚ اﻟﺮادﻳﻮي . وﰲ ﻏﻀﻮن ﻋ ـ ﴩ ﺳﻨﻮات ﺳـﺘ ﺘﻴﺢ اﻟﻨﺴـﺨﺔ ا ُﺤﺴّﻨﺔ اﻟﺘﺎﻟﻴﺔ ﻣ ﻦ ﻣﺮﺻﺪ اﻟﺘﺪاﺧﻞ اﻟﺮادﻳﻮي اﻟﻜﺒ دراﺳﺔ اﻷﻣﻮﻧﻴﺎ ا ﺤﻴﻄﺔ ﺑﺎﻟﻨﺠﻮ م ﻋﲆ ﻧﻄﺎق ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤﴘ ". ﻻ ﻳ ﻌﺰز ﻫﺬا اﻟ ﻌﻤـﻞ ﻓﻬﻤﻨـﺎ ﻟﻜﻴﻔﻴـﺔ ﺗﺸـﻜﻞ اﻟﻨﺠﻮم اﻟﻀﺨﻤﺔ ﻓﺤﺴﺐ ﺑﻞ ﻟﻪ أﻳﻀ ﺎُ آﺛﺎر ﻋﲆ أﺳﺌﻠﺔ أوﺳﻊ ﺣﻮل ﺗﻄـﻮر ا ﺠـﺮات واﻹﺛـﺮاء اﻟﻜﻴﻤﻴﺎﺋﻲ ﰲ اﻟﻜﻮن . ًﺗﻠﻌﺐ اﻟﻨﺠﻮم اﻟﻀﺨﻤﺔ دوراً ﻣﻬﻤﺎ ﻛﻤﺤﺮﻛﺎت ﻛﻮﻧﻴﺔ وﺗﺪﻓﻊ اﻟﺮﻳﺎح واﻻﻧﻔﺠﺎرات اﻟﺘﻲ ﺗﻨﻘﻞ إﱃ ا ﺠﺮات ﺑﺬور اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ . ﻏـﺎز ـﺎ اﻷﻣﻮﻧ ﺴـﻘﻂ ﻓـﻲ ﻗـﺮص اﻟـ ا ﻢ ا ﻟﻤﻐـﺬ ﻟﻠﻨ ﻢ HW2 ﺿﻤﻦ اﻟﻨﻈﺎم اﻟﻨ ﻤﻲ اﻟﻤﻠﺘﻬﺐ A ] NSF/AUI/NSFNRAO/B.Saxton [ ﻳﻮﻟﻴﻮ - ﺃﻏﺴﻄﺲ 2 0 2 5