Free Astronomy Magazine March-April 2025 ARABIC VERSION

LowellObservatory,combiningdata from the Atacama Large Mil- limeter/submillimeter Array (ALMA) and Keck Observatory, has unveiled intriguing findings about planet formation in this binary star system, known as DF Tau, along with other systems in this region. DF Tau consists of two young stars with nearly equal masses, orbiting each other every 48 years. Since both stars likely formed together, with the same composition in the sameenvironment,astronomers would expect them to share differ- ent things in common, like having similar circumstellar disks. But thisis not the case—while the brighter primary star has an active innerdisk, the secondary star’s inner disk appears to have almost completely disappeared. These unexpected dif- ferences challenge current theories of disk evolution and planet forma- tion. Like a potter’s wheel shapes clay into various forms, a circum- stellar disk provides the materials andenvironmentforplanetsto form. Over time, the dust and gas in the disk will clump together, eventuallyformingplanets,moons, and other celestial bodies. The disks won’t last forever — as a star ma- tures and planets form, the disk gradually disappears. So, what caused the unusual dissipation ob- served in the circumstellar disk of the secondary star? High-resolution ALMA imaging, combinedwithopticalandinfrared data from other telescopes, al- lowedresearcherstostudy,analyze, and compare the stars’ properties and disks. This binary has a rela- tively small, tight orbit, which means gravity truncates the outer parts of the disk, but it is unlikely that the current binary orbit could alter the inner disk. Instead, other processes may be at work. “Thedispersalofcircumstellardisks is a complicated process with many unknowns. By looking at systems that form together, we can control one major variable: time. DF Tau and other systems in our survey tell usthatdiskevolutionisn’tstrictlya function of time; other processesare at play,” shares Taylor Kutra of Lowell Observatory, lead author of this research. Binary systems like DF Tau and other sources in this ALMA survey offer a natural laboratory to study how circumstellar disks evolve. Understanding these processes is essential for refining models of planetformationbecausediskevo- lution sets the timescale on which planet formation occurs. This research highlights the diver- sity of disk behaviors and under- scores the need for further studies to unravel the factors influencing their lifespans and structures. These findings deepen our understanding of binary star systems and shed light on the broader mechanisms shaping planetary systems across thegalaxy.  ﻣﻦ ﻣﺮﺻﺪ أﺗﺎﻛﺎﻣﺎ اﻟﻜﺒـ ا ﻠﻴﻤـﱰ دون /ي ا ﻠﻴﻤﱰ أ ﺎ)ي ( وﻣﺮﺻـﺪ ﻛﻴـﻚ ﻋـﻦ ﻧﺘـﺎﺋﺞ ﻣﺜ ة ﻟﻼﻫﺘﻤﺎم ﺣـﻮل ﺗﺸـﻜﻞ اﻟﻜﻮاﻛـﺐ ﰲ اﻟ ﻨﻈﺎم اﻟﻨﺠﻤـ ﻲ اﻟﺜﻨـﺎﺋﻲ ا ﻌـﺮوف ﺑﺎﺳـ ﻢ Tau) DF ( إﱃ ﺟﺎﻧﺐ أﻧﻈﻤﺔ ﻧﺠﻤﻴﺔ أﺧـﺮى ﻣﻮﺟﻮدة ﰲ ﻫﺬه ا ﻨﻄﻘﺔ . ﻳﺘ ـﺄﻟﻒ Tau) DF ( ﻣ ـﻦ ﻧﺠﻤــ ﺷــ ﺎﺑ ﻣﺘﺴﺎوﻳ ﰲ اﻟﻜﺘﻠﺔ ﺗﻘﺮﻳﺒﺎً ﻳـﺪور اﺣـﺪﻫﻤﺎ اﻷﺧﺮ ﺣﻮل ﻛﻞ 48 ﺮاً وﻧﻈ ﺎً ﻋﺎﻣ ﻷن اﻟﻨﺠﻤ رﺑﻤﺎ ﺗﺸﻜﻼ ﻣﻌﺎً ﺑﻨﻔﺲ اﻟﱰﻛﻴـﺐ ﰲ ﻧﻔـﺲ اﻟﺒﻴﺌﺔ ﻳﺘﻮﻗﻊ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ أ ن ﻳﺸـﱰﻛﺎ ﰲ أﺷﻴﺎء ﻣﺨﺘﻠﻔـﺔ ﻋـﲆ ﺳـﺒﻴﻞ ا ﺜـﺎل وﺟـﻮد أﻗﺮاص ﻣﺤﻴﻄﻴﺔ ﻣﺘﺸﺎﺑﻬﺔ ﻟﻜﻦ ﻫـﺬا ﻟـﻴﺲ ﻫﻮ اﻟﺤﺎل ﻓﺒﻴﻨﻤﺎ ﻳﺤﺘﻮي اﻟـﻨﺠﻢ اﻷﺳـﺎﳼ اﻷﻛﺜﺮ ﺳﻄﻮﻋﺎً ﻋﲆ ﻗﺮص داﺧﲇ ﻧﺸﻂ ﻳﺒﺪو أن اﻟﻘـﺮص اﻟـﺪا ﺧﲇ ﻟﻠـﻨﺠﻢ اﻟﺜـﺎﻧﻮي ﻗـﺪ اﺧﺘﻔﻰ ﺗﻤﺎﻣ ﺎً . ﺎً ﺗﻘﺮﻳﺒ ﺗﺘﺤـﺪى ﻫــﺬه اﻻﺧﺘﻼﻓـﺎت ﻏـ ا ﺘﻮﻗﻌــﺔ اﻟﻨﻈﺮﻳﺎت اﻟﺤﺎﻟﻴـ ﺔ ﺣـﻮل ﺗﻄـ ﻮر اﻟﻘـﺮص وﺗﻜﻮﻳﻦ اﻟﻜﻮاﻛﺐ ﻓﻤﺜﻞ ﻋﺠﻠﺔ اﻟﺨﺰاف اﻟﺘﻲ ﺗﺸـﻜﻞ اﻟﻄـ ﰲ أﺷـﻜﺎل ﻣﺨﺘﻠﻔـﺔ ﻳـﻮﻓﺮ اﻟﻘـﺮص ا ﺤــﻴﻂ ﺑ ـﺎﻟﻨﺠﻢ ا ـﻮاد واﻟﺒ ﻴﺌ ـﺔ ﻟﺘﻜﻮﻳﻦ اﻟﻜﻮاﻛـﺐ . ﺑﻤـﺮور اﻟﻮﻗـﺖ ﺳـﻮف ﻳﺘﻜﺘﻞ اﻟﻐﺒﺎر واﻟﻐﺎز ﰲ اﻟﻘـﺮص ﻣﻌـ ﺎً ﻣﻤـﺎ ﻳﺸﻜﻞ ﰲ اﻟﻨﻬﺎﻳﺔ اﻟﻜﻮاﻛﺐ واﻷﻗﻤﺎر واﻷﺟﺮام اﻟﺴﻤﺎوﻳﺔ اﻷ . ﺧﺮى ﻟـﻦ ﺗـﺪوم اﻷﻗـﺮاص إﱃ اﻷﺑﺪ ﻓ ﻤﻊ ﻧﻀﻮج اﻟﻨﺠﻢ وﺗﻜـﻮﻳﻦ اﻟﻜﻮاﻛـﺐ ﻳﺨﺘﻔﻲ اﻟﻘﺮص ﺗﺪرﻳﺠﻴﺎً . إذن ﻣﺎ اﻟﺬي ﺗﺴﺒﺐ ﰲ اﻟﺘﺒﺪﻳـﺪ ﻏـ ا ﻌﺘـﺎد اﻟﺬي رﺻﺪ ﺑﺸﻜﻞ واﺿﺢ ﰲ اﻟﻘﺮص ا ﺤﻴﻂ ﺑﺎﻟﻨﺠﻢ اﻟﺜﺎﻧﻮي؟ ﻟ ﻘﺪ ﺳﻤﺢ اﻟﺘﺼﻮﻳﺮ ﻋﺎﱄ اﻟﺪﻗـﺔ ﺑﺎﺳـﺘﺨﺪام ﺗﻠﺴﻜﻮب ﻣﺮﺻـﺪ أ ـﺎ إﱃ ﺟﺎﻧـﺐ اﻟﺒﻴﺎﻧـﺎت اﻟﺒﴫـﻳﺔ واﻷﺷـ ﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء ﻣ ـﻦ ﺗﻠﺴﻜﻮﺑﺎت أﺧﺮى ﻟﻠﺒﺎﺣﺜ ﺑﺪراﺳﺔ وﺗﺤﻠﻴﻞ وﻣﻘﺎرﻧﺔ ﺧﺼﺎﺋﺺ اﻟﻨﺠﻮم وأﻗﺮاﺻﻬﺎ . ﻳﺘﻤﺘﻊ ﻫﺬ ا اﻟﺜﻨـﺎﺋﻲ اﻟﻨﺠﻤـﻲ ﺑﻤـﺪار ﺿـﻴﻖ ﺻﻐ ﻧﺴﺒﻴﺎً ﻣﻤﺎ ﻳﻌﻨﻲ أن اﻟﺠﺎذﺑﻴﺔ ﺗﻘﻄـﻊ اﻷﺟﺰاء اﻟﺨﺎرﺟﻴﺔ ﻣﻦ اﻟﻘﺮص وﻟﻜ ﻦ ﻣﻦ ﻏ ا ﺮﺟﺢ أن ﻳﻐ ا ﻣﺪار ﻟﺜﻨﺎﺋﻲ اﻟﻨﺠﻤﻲ اﻟﺤﺎﱄ اﻟﻘﺮص اﻟﺪاﺧﲇ . ﺑﺪﻻً ﻣﻦ ذﻟﻚ ﻗﺪ ﺗﻜﻮن ﻫﻨﺎك ﻋﻤﻠﻴﺎت أﺧﺮى ﺗﻌﻤﻞ ﻋﲆ ذﻟﻚ . إن ﺗﺸﺘﺖ اﻷﻗﺮاص ا ﺤﻴﻄﺔ ﺑﺎﻟﻨﺠﻮم ﻋﻤ ﻠﻴﺔ ﻣﻌﻘﺪة ﻣﻊ ﻋﻤﻠﻴﺎت ﻣﺠﻬﻮﻟﺔ ﻦ ﺧﻼل ﻣ ﻟﺬﻟﻚ اﻟﻨﻈﺮ إﱃ اﻷﻧﻈﻤﺔ اﻟﺘﻲ ﺗﺘﺸﻜﻞ ﻣﻌـ ﺎً ﻳﻤﻜـﻦ اﻟﺘﺤﻜﻢ ﰲ ﻣﺘﻐ رﺋﻴﴘ واﺣﺪ : اﻟﻮﻗﺖ . ﻳﺨﱪﻧﺎ ) ﻧﻈﺎم DF Tau ( واﻷﻧﻈﻤﺔ اﻷﺧـﺮى ﰲ ﻣﺴـﺤﻨﺎ أن ﺗﻄـﻮر اﻷﻗـﺮاص ﻻ ﻳـﺮﺗﺒﻂ ﺑﺸﻜﻞ ﻗﻮي ﺑﺎﻟﻮﻗﺖ ﻓ ﻬﻨﺎك ﻋﻤﻠﻴﺎت أﺧـﺮى ﺗﻠﻌﺐ دو ﻳﺸـ " اً ر ﺎرﻛﻨﺎ ﺗـﺎﻳﻠﻮر ﻛـﻮﺗﺮا ﻣـﻦ ﻣﺮﺻﺪ ﻟﻮﻳﻞ ا ﺆﻟﻒ اﻟﺮﺋﻴﴘ ﻟﻬﺬا اﻟﺒ . ﺤﺚ ﺗﻮﻓﺮ اﻷﻧﻈﻤﺔ اﻟﻨﺠﻤﻴﺔ اﻟﺜﻨﺎﺋﻴﺔ اﻟﺘﻲ ﺗﺸـﺒﻪ Tau) DF( وا ﺼﺎدر اﻷﺧﺮى ﰲ ﻣﺴﺢ ﻣﺮﺻﺪ أ ﺎ ﻫﺬا ﻣﺨﺘﱪ اً ﺎً ﻃﺒﻴﻌﻴ ﻟﺪراﺳﺔ ﻛﻴﻔﻴﺔ ﺗﻄﻮر اﻷﻗﺮاص ا ﺤﻴﻄﺔ ﺑﺎﻟﻨﺠﻮم . إن ﻓﻬــﻢ ﻫــﺬه اﻟﻌﻤﻠﻴــﺎت أﻣــﺮ ﴐوري ﻟﺘﺤﺴ ﻧﻤﺎذج ﺗﺸﻜﻞ اﻟﻜﻮاﻛﺐ ﻷن ﺗﻄـﻮر اﻟﻘﺮص ﻳﺤﺪد اﻹﻃﺎر اﻟﺰﻣﻨﻲ اﻟـﺬي ﻳﺤـﺪث ﻓﻴﻪ ﺗﺸ ﻜﻞ اﻟﻜﻮاﻛﺐ . ﻳﺴـﻠﻂ ﻫـﺬا اﻟﺒﺤـﺚ اﻟﻀـﻮء ﻋــﲆ ﺗﻨــﻮع ﺳﻠﻮﻛﻴﺎت اﻟﻘﺮص وﻳﺆﻛﺪ ﻋـﲆ اﻟﺤﺎﺟـﺔ إﱃ ﻣﺰﻳﺪ ﻣﻦ اﻟﺪراﺳﺎت ﻟﻜﺸﻒ اﻟﻌﻮاﻣـﻞ اﻟﺘـﻲ ﺗﺆﺛﺮ ﻋﲆ أﻋﻤﺎرﻫﺎ وﺑﻨﻴﺘﻬﺎ . ﺗﻌﻤﻞ ﻫـﺬه اﻟﻨﺘـﺎﺋﺞ ﻋـﲆ ﺗﻌﻤﻴـﻖ ﻓﻬﻤﻨـﺎ ﻷﻧﻈﻤﺔ اﻟﻨﺠﻮم اﻟﺜﻨﺎﺋﻴﺔ وﺗﻠﻘﻲ اﻟﻀﻮء ﻋـﲆ اﻵﻟﻴ ـﺎت اﻷوﺳــﻊ اﻟﺘ ـﻲ ﺗﺸ ـﻜﻞ اﻷﻧﻈﻤــﺔ اﻟﻜﻮﻛﺒﻴﺔ ﻋﱪ ا ﺠﺮة . 7 ﺃﺑﺮﻳﻞ - ﻣﺎﺭﺱ 2 0 2 5 T Tau FO Tau