Free Astronomy Magazine January-February 2024 ARABIC VERSION

rate, limiting the time planets have to form. “How did we get here? It really goes back to that big ques- tion, and SZ Cha is the same type of young star, a T-Tauri star, as our Sun was 4.5 billion years ago at the dawn of the solar system,” said astronomer Catherine Espaillat of Boston University, in Massachusetts, who led both the 2008 Spitzer ob- servations and the newly published Webb results. “The raw materials for Earth, and eventually life, were pres- ent in the disk of material that sur- rounded the Sun after it formed, and so studying these other young systems is as close as we can get to going back in time to see how our own story began.” Scientists use neon as an indicator of how much, and what type, of radia- tion is hitting and eroding the disk around a star. When Spitzer ob- served SZ Cha in 2008, it saw an out- lier, with neon readings unlike any other young T-Tauri disk. The differ- ence was the detection of neon III, which is typically scarce in proto- planetary disks that are being pum- meled by high-energy X-rays. This meant that the high-energy radia- tion in the SZ Cha disk was coming from ultraviolet (UV) light instead of X-rays. Besides being the lone odd- ball result in a sample of 50-60 young stellar disks, the UV vs. X-ray difference is significant for the life- time of the disk and its potential planets. “Planets are essentially in a race against time to form up in the disk before it evaporates,” ex- plained Thanawuth Thanathibodee of Boston University, another as- tronomer on the research team. “In computer models of developing sys- tems, extreme ultraviolet radiation allows for 1 million more years of planet formation than if the evapo- ration is predominately caused by X- rays.” So, SZ Cha was already quite the puzzle when Espaillat’s team re- turned to study it with Webb, only to find a new surprise: The unusual neon III signature had all but disap- peared, indicating the typical domi- nance of X-ray radiation. The research team thinks that the differences in neon signatures in the SZ Cha system are the result of a variable wind that, when present, absorbs UV light and leaves X-rays to pummel the disk. Winds are common in a system with a newly formed, energetic star, the team says, but it is possible to catch the system during a quiet, wind-free pe- riod, which is what Spitzer hap- pened to do. “Both the Spitzer and Webb data are excellent, so we knew this had to be something new we were ob- serving in the SZ Cha system – a sig- nificant change in conditions in just 15 years,” added co-author Ardjan Sturm of Leiden University, Leiden, Netherlands. Espaillat’s team is already planning more observations of SZ Cha with Webb, as well as other telescopes, to get to the bottom of its mysteries. “It will be important to study SZ Cha, and other young systems, in multiple wavelengths of light, like X-ray and visible light, to discover the true nature of this variability we’ve found,” said co-author Caeley Pittman of Boston University. “It’s possible that brief, quiet periods dominated by extreme UV radiation are common in many young plane- tary systems, but we just have not been able to catch them.” “Once again, the universe is show- ing us that none of its methods are as simple as we might like to make them. We need to rethink, re-ob- serve, and gather more information. We’ll be following the neon signs,” said Espaillat.    JANUARY-FEBRUARY 2024 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 17 ﺗﺘﺸﻜﻞ ﻓﻴﻪ اﻟﻜﻮاﻛﺐ ." ﻛﻴﻒ وﺻﻠﻨﺎ إﱃ ﻫﻨﺎ؟ ﻳﻌﻮد اﻷﻣﺮ ﺣﻘًﺎ إﱃ ﻫﺬا اﻟﺴﺆال اﻟﻜﺒ ، إس ) ( زد ﺗﺸﺎﻣﻴﻠﻮﻧﺘﻴﺲ ﻫﻮ ﻧﻔﺲ ﻧـﻮع اﻟﻨﺠـﻮم اﻟﺸــﺎﺑﺔ، اﻟــ ﻨﺠﻢ T-Tauri ، ﻛﻤــﺎ ﻛﺎﻧــﺖ اﻟﺸﻤﺲ ﻗﺒﻞ 4.5 ﻣﻠﻴـﺎر ﺳـﻨﺔ ﻋﻨـﺪ ﻓﺠـﺮ اﻟﻨﻈـﺎم اﻟﺸﻤـ "ﴘ، ـ ﻗﺎﻟـﺖ ﻋﺎ ـﺔ اﻟﻔﻠـﻚ ﻛﺎﺛﺮﻳﻦ إﺳﺒ ﺎﻳﻼت ﻣﻦ ﺟﺎﻣﻌـﺔ ﺑﻮﺳـﻄﻦ ﰲ ﻣﺎﺳﺎﺗﺸﻮﺳﺘﺲ، اﻟﺘﻲ ﻗﺎدت ﻋﻤﻠﻴﺎت رﺻـﺪ ﺳﺒﻴﺘﺰر ﻋﺎم 2008 وﻧﺘﺎﺋﺞ وﻳـﺐ ا ﻨﺸـﻮرة . " ﺪﻳﺜًﺎ ﺣ ﻛﺎﻧﺖ ا ﻮاد اﻟﺨﺎم ﻟﻸرض واﻟﺤﻴـﺎة ﰲ ﻧﻬﺎﻳﺔ ا ﻄﺎف ﻣﻮﺟـﻮدة ﰲ ﻗـﺮص ا ـﺎ دة اﻟﺘﻲ أﺣﺎﻃﺖ ﺑﺎﻟﺸﻤﺲ ﺑﻌﺪ ﺗﺸﻜﻠﻬﺎ وﺑﺎﻟﺘﺎﱄ ﻓﺈن دراﺳﺔ ﻫﺬه اﻷﻧﻈﻤﺔ اﻟﺸـﺎﺑﺔ اﻷﺧـﺮى ﻫﻲ أﻗﺮ ب ﻣﺎ ﻳﻤﻜﻦ اﻟﺤﺼﻮل ﻋﻠﻴﻪ واﻟﻌﻮدة إﱃ ا ـﺎﴈ ﻌﺮﻓ ـﺔ ﻛﻴ ـﻒ ﺑ ـﺪأت ﻗﺼـ .ﺘﻨﺎ ﻳﺴﺘﺨﺪم اﻟﻌﻠﻤﺎء اﻟﻨﻴﻮن ﻛﻤﺆﴍ ﻋﲆ ﻣﻘﺪار وﻧﻮع اﻹﺷﻌﺎع اﻟﺬي ﻳﴬب اﻟﻘﺮص ا ﺤﻴﻂ ﺑـﺎﻟﻨﺠﻢ وﻳـﺆدي إﱃ ﺗﺂﻛﻠـﻪ وﻋﻨـﺪﻣﺎ رﺻـﺪ ﺳﺒﻴﺘﺰر اﻟﻘـﺮص إس زد ) ( ﺗﺸـﺎﻣﻴﻠﻮﻧﺘﻴﺲ ﰲ ﻋﺎم 2008 رأى وﺟﻮد اً ﻏﺮﻳﺒﺎً ﻣﻊ ﻗﺮاءات ﻧﻴﻮن ﻻ ﺗ ﺸـﺒﻪ أي ﻗـﺮص T-Tauri ﺷـﺎب آﺧﺮ . ﻛﺎن اﻻﺧﺘﻼف ﻫﻮ اﻛﺘﺸﺎف اﻟﻨﻴﻮن III وﻫﻮ ﻧﺎدر ﻋﺎدة ﰲ أﻗﺮاص اﻟﻜﻮاﻛﺐ اﻷوﻟﻴﺔ اﻟﺘـﻲ ﺗﺘﻌﺮض ﻟﻸﺷـﻌﺔ اﻟﺴـﻴﻨﻴﺔ ﻋﺎﻟﻴـﺔ اﻟﻄﺎﻗـﺔ وﻫﺬا ﻳﻌﻨﻲ أن اﻹ ﺷﻌﺎع ﻋﺎﱄ اﻟﻄﺎﻗﺔ ا ﻮﺟﻮد إس زد ) ﰲ ﻗﺮص ( ﺗﺸﺎﻣﻴﻠﻮﻧﺘﻴﺲ ﺗﻲ ﺄ ﻛﺎن ﻳ ﻣﻦ اﻷﺷـﻌﺔ ﻓـﻮق اﻟ ﺒﻨﻔﺴـﺠﻴﺔ ﺑـﺪﻻً ﻣـﻦ اﻷﺷﻌ ﺔ اﻟﺴﻴﻨﻴﺔ وإﱃ ﺟﺎﻧﺐ ﻛﻮﻧﻬﺎ اﻟﻨﺘﻴﺠـﺔ اﻟﻔﺮدﻳﺔ اﻟﻮﺣﻴﺪة ﰲ ﻋﻴﻨﺔ ﻣﻜﻮﻧﺔ ﻣـﻦ 50 إﱃ 60 ﺎً ﻗﺮﺻ ﻧﺠﻤﻴـ ﺎً ﺎً ﺷـﺎﺑ ﻓـﺈن اﻟﻔـﺮق ﺑـ اﻷﺷﻌﺔ ﻓﻮق اﻟﺒﻨﻔﺴﺠﻴﺔ واﻷﺷﻌﺔ اﻟﺴـﻴﻨﻴﺔ ﻣﻬﻢ ﺑﺎﻟﻨﺴـﺒﺔ ﻟﻌﻤـﺮ اﻟﻘـﺮص واﻟﻜﻮاﻛـﺐ ا ﺤﺘﻤﻠﺔ . أوﺿﺢ ﺛﺎﻧـﺎووث ﺛﺎﻧـﺎﺛﻴﺒﻮدي ﻣـﻦ ﺟﺎﻣﻌـﺔ ﺑﻮﺳﻄﻦ، وﻫﻮ ﻋﺎﻟﻢ ﻓﻠﻜـﻲ آﺧـﺮ ﰲ ﻓﺮﻳـﻖ اﻟﺒﺤﺚ " : إن اﻟﻜﻮاﻛﺐ ﰲ اﻷﺳـﺎس ﰲ ﺳـﺒﺎق ﻣـﻊ اﻟـﺰﻣﻦ ﻟﺘﺘﺸـﻜﻞ ﰲ اﻟﻘـﺮص ﻗﺒـﻞ أن ﻳﺘﺒﺨﺮ ."» ﰲ اﻟﻨﻤﺎذج اﻟﺤﺎﺳـﻮﺑﻴﺔ ﻟﻸﻧﻈﻤـﺔ ا ﺘﻄﻮرة ﻳﺴﻤﺢ اﻹﺷﻌﺎع ﻓﻮق اﻟﺒﻨﻔﺴـﺠﻲ اﻟﺸـﺪﻳﺪ ﺑﺘﻜـﻮﻳﻦ اﻟﻜﻮاﻛـﺐ ﻠﻴـﻮن ﺳـﻨﺔ ﻠﻴﻮن ﺳﻨﺔ ﻟﺘﺸﻜﻞ اﻟﻜﻮاﻛﺐ إذا اﻟﺘﻐ ﻛﺎن ﺑﺴﺒﺐ اﻷﺷﻌﺔ اﻟﺴﻴﻨﻴﺔ ﻟﺬﻟﻚ . إس زد ) ﻛﺎن ( ﺗﺸﺎﻣﻴﻠﻮﻧﺘﻴﺲ ﺑﺎﻟﻔﻌﻞ ﻟﻐﺰ اً اً ﻛﺒ ﻋﻨﺪﻣﺎ ﻋﺎد ﻓﺮﻳﻖ اﺳﺒﺎﻳﻼت ﻟﺪراﺳﺘﻪ ﺑﻮاﺳﻄﺔ ﺗﻠﺴﻜﻮب وﻳﺐ ﻓﻘﻂ ﻟﻴﺠﺪوا ﻣﻔﺎﺟﺄة ﺟﺪﻳـﺪة : ﺗﻮﻗﻴـﻊ اﻟﻨﻴﻮن اﻟﺜ ﺎﻟﺚ ﻏ اﻟﻌﺎدي ﻗﺪ اﺧﺘﻔﻰ ﺗﻘﺮﻳﺒﺎً ﻣﻤﺎ ﻳﺸ إﱃ اﻟﻬﻴﻤﻨﺔ اﻟﻨﻤﻮذﺟﻴـﺔ ﻹﺷـﻌﺎع اﻷﺷﻌﺔ اﻟﺴﻴﻨﻴﺔ . ﻳﻌﺘﻘـﺪ ﻓﺮﻳـﻖ اﻟﺒﺤـﺚ أن اﻻﺧﺘﻼﻓ ﺎت ﰲ ﺑﺼﻤﺎت اﻟﻨﻴﻮن ﰲ ﻧﻈﺎم إس ) ( زد ﺗﺸـﺎﻣﻴﻠﻮﻧﺘﻴﺲ ﻫ ـﻲ ﻧﺘﻴﺠ ـﺔ ﻟﻠﺮﻳ ـﺎح ا ﺘﻐ ة اﻟﺘﻲ ﻋﻨﺪ وﺟﻮدﻫﺎ ﺗﻤـﺘﺺ اﻟﻀـﻮء ﻓﻮق اﻟﺒﻨﻔﺴﺠﻲ و ﺗـﱰك اﻷﺷـﻌﺔ اﻟﺴـﻴﻨﻴﺔ ﻟﺘﴬب اﻟﻘﺮص ، وﻳﻘﻮل اﻟﻔﺮﻳﻖ إن اﻟﺮﻳـﺎح ﺷﺎﺋﻌﺔ ﰲ ﻧﻈﺎم ﻳﺤﺘﻮي ﻋـﲆ ﻧﺠـﻢ ﻧﺸـﻴﻂ ﺣﺪﻳﺚ اﻟﺘﻜﻮﻳﻦ، ﻟﻜﻦ ﻣـﻦ ا ﻤﻜـﻦ اﻟﺘﻘـﺎط اﻟﻨﻈﺎم ﺧـﻼل ﻓـﱰة ﻫﺎ دﺋـﺔ وﺧﺎﻟﻴـﺔ ﻣـﻦ اﻟﺮﻳﺎح، وﻫﻮ ﻣﺎ ﺣﺪث ﻟﺴﺒﻴﺘﺰر " . إن ﺑﻴﺎﻧﺎت ﺗﻠﺴﻜﻮب ﺳﺒ ﺗﺰ وﺗﻠﺴﻜﻮب وﻳـﺐ ﻣﻤﺘـﺎزة ﻟﺬﻟﻚ ﻋﺮﻓﻨ ﺎ أن ﻫﺬا ﻳﺠـﺐ أن ﻳﻜـﻮن ﺷـﻴﺌًﺎ اً ﺟﺪﻳــﺪ ﻛﻨــﺎ ﻧﺮﺻــﺪه إس زد ) ﰲ ﻧﻈــﺎم ( ﺗﺸﺎﻣﻴﻠﻮﻧﺘﻴﺲ وﻫﻮ ﺗﻐﻴ ﻛﺒ ﰲ اﻟﻈـﺮوف ﺧـﻼل 15 ﺎً ﻋﺎﻣـ " ﻓﻘـﻂ وأﺿـﺎف ا ﺆﻟـﻒ ا ﺸﺎرك أردﺟﺎن ﺷﺘﻮرم ﻣﻦ ﺟﺎﻣﻌـﺔ ﻟﻴـ ﺪن ﺑ ﻟﻴﺪن . ﻬﻮﻟﻨﺪا ﻳﺨﻄﻂ ﻓﺮﻳﻖ إﺳﺒﺎﻳﻼت ﺑﺎﻟﻔﻌﻞ ﺰﻳـﺪ ﻣـﻦ ﻋﻤﻠﻴﺎت اﻟﺮﺻﺪ ﻟـ SZ Cha ﻣـﻊ ﺗﻠﺴـﻜﻮب وﻳﺐ ﺑﺎﻹﺿـﺎﻓﺔ إﱃ اﻟﺘﻠﺴـﻜﻮﺑﺎت اﻷﺧـﺮى، ﻟﻠﻮﺻﻮل إﱃ ﺣﻞ أﻟﻐﺎزه " . ﺳﻴﻜﻮن ﻣﻦ ا ﻬـﻢ دراﺳﺔ SZ Cha واﻷﻧﻈﻤﺔ اﻟﺸﺎﺑﺔ اﻷﺧﺮى ﰲ أﻃﻮال ﻣﻮﺟﻴﺔ ﻣﺘﻌـﺪدة ﻣـﻦ اﻟﻀـﻮء ﻣﺜـﻞ اﻷ ﺷﻌﺔ اﻟﺴﻴﻨﻴﺔ واﻟﻀﻮء ا ﺮﺋـﻲ ﻻﻛﺘﺸـﺎف اﻟﻄﺒﻴﻌـﺔ اﻟﺤﻘﻴﻘﻴـﺔ ﻟﻬـﺬا اﻟﺘﺒـﺎﻳﻦ اﻟ ـﺬي " وﺟﺪﻧﺎه ، ﻗﺎل ا ﺆﻟﻒ ا ﺸﺎرك ﻛﻴﲇ ﺑﻴﺘﻤـﺎن ﻣﻦ ﺟﺎﻣﻌﺔ ﻛﺎﻟﻴﻔﻮرﻧﻴﺎ و ﺟﺎﻣﻌـﺔ ﺑﻮﺳـﻄﻦ " ﻣﻦ ا ﻤﻜﻦ أن ﺗﻜـﻮن اﻟﻔـﱰات اﻟﻘﺼـ ة واﻟﻬﺎدﺋﺔ اﻟﺘﻲ ﺗﻬﻴﻤﻦ ﻋﻠﻴﻬﺎ اﻷﺷـﻌﺔ ﻓـﻮق اﻟﺒﻨﻔﺴﺠﻴﺔ اﻟﺸﺪﻳﺪة ﺷﺎﺋﻌﺔ ﰲ اﻟﻌﺪﻳـﺪ ﻣـﻦ أﻧﻈﻤﺔ اﻟﻜﻮاﻛﺐ اﻟﻨﺎﺷﺌﺔ ﻟـ ﻟﻜﻨﻨﺎ ﻢ ﻧـﺘﻤﻜﻦ ﻣﻦ اﻟﺘﻘﺎﻃﻬﺎ . ﻣﺮة أﺧﺮى ﻳﺒ ﻟﻨﺎ اﻟﻜﻮن أﻧـﻪ ﻻ ﳾء ﻣـﻦ ﻧﻈﺮﻳﺎﺗﻪ ﺑﺎﻟ ﺒﺴﺎﻃﺔ اﻟﺘﻲ ﻧﺮﻳﺪﻫﺎ . ﻧﺤﻦ ﺑﺤﺎﺟـﺔ إﱃ إﻋـﺎدة اﻟﺘﻔﻜـ وإﻋـﺎدة ا ﺮاﻗﺒﺔ وﺟﻤﻊ ا ﺰﻳﺪ ﻣـﻦ ا ﻌﻠﻮﻣـﺎت . ﻗـﺎل إﺳﺒﺎﻳﻼت " : ﺳﻨﺘﺒﻊ إﺷﺎرات اﻟﻨﻴﻮن ." ﻈﻬــﺮ اﻟﺮﺳــﻢ ﻫــﺬا ا ﻟﺘﺨ ﻠــﻲ اﻟــﻨ ﻢ اﻟﺸــﺎب (SZ Cha) إسزد ) ( ﺗﺸــﺎﻣ ﻠﻮﻧﺘ ﺲﻣﺤــﺎط ﻘــﺮصﻣــﻦ اﻟﻐ ﺎر واﻟﻐﺎزﻣﻊ إﻣ ﺎﻧ ﺔ ﺗﺸﻜﻴﻞ ﻧﻈﺎم ﻮﻛ . ذات ﻣﺮة ﺎن ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤﺴﻲ ﻳ ﺪو ﺑﻬ ﺬا اﻟﺸ ﻞ ﻗﺒﻞ أن ﺗﺘ ـــﺎت ﺸــ ﻞ اﻟ ﻮاﻛـــﺐواﻷﻗﻤــﺎرواﻟ ﻮ ﻜ و ﺎﻧـــﺖ اﻟﻤ ﻮﻧــﺎت اﻟـــ ـ ﺨﺎم ﻤــﺎ ﻓـــﻲذ ـــﺎة ﻟـــﻚ ﺗﻠــﻚ اﻟﻼزﻣـــﺔ ﻟﻠﺤ ﻋﻠﻰ اﻷرض ﻣﻮﺟﻮدة اﻷوﻟﻲ ﻓﻲﻗﺮص اﻟﺸﻤﺲ اﻟ ﻮﻛ . - ﻳﻨﺎﻳﺮ ﻓﺒﺮﺍﻳﺮ 2 0 2 4