Free Astronomy Magazine May-June 2023 ARABIC VERSION

MAY-JUNE 2023 heavy water form under different conditions, their ratio can be used to trace when and where the water was formed. For instance, this ratio in some Solar System comets has been shown to be similar to that in water on Earth, suggesting that comets might have delivered water to Earth. The journey of water from clouds to young stars, and then later from comets to planets has previously been observed, but until now the link between the young stars and comets was missing. “V883 Orionis is the missing link in this case,” says Tobin. “The composition of the water in the disc is very similar to that of comets in our own Solar Sys- tem. This is confirmation of the idea that the water in planetary systems formed billions of years ago, before the Sun, in interstellar space, and has been inherited by both comets and Earth, relatively unchanged.” But observing the water turned out to be tricky. “Most of the water in planet-forming discs is frozen out as ice, so it’s usually hidden from our view,” says co-author Margot Leemker, a PhD student at Leiden Observatory in the Netherlands. Gaseous water can be detected thanks to the radiation emitted by molecules as they spin and vibrate, but this is more complicated when the water is frozen, where the mo- tion of molecules is more con- strained. Gaseous water can be found towards the centre of the discs, close to the star, where it’s warmer. However, these close-in re- gions are hidden by the dust disc it- self, and are also too small to be imaged with our telescopes. Fortunately, the V883 Orionis disc was shown in a recent study to be unusually hot. A dramatic outburst of energy from the star heats the disc, “up to a temperature where water is no longer in the form of ice, but gas, enabling us to detect it,” says Tobin. The team used ALMA, an array of radio telescopes in northern Chile, to observe the gaseous water in V883 Orionis. Thanks to its sensitivity and ability to discern small details they were able to both detect the water and determine its composi- tion, as well as map its distribution within the disc. From the observa- tions, they found this disc contains at least 1200 times the amount of water in all Earth’s oceans. In the future, they hope to use ESO’s upcoming Extremely Large Tele- scope and its first-generation instru- ment METIS. This mid-infrared instrument will be able to resolve the gas-phase of water in these types of discs, strengthening the link of water’s path all the way from star-forming clouds to solar systems. “This will give us a much more com- plete view of the ice and gas in planet-forming discs,” concludes Leemker.     A ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ ٢٢ ﻧﻈﺮًا ﻷن ا ﺎء اﻟﺒﺴﻴﻂ واﻟﺜﻘﻴﻞ ﻳﺘﺸﻜﻞ ﰲ ﻇﻞ ﻇﺮوف ﻣﺨﺘﻠﻔﺔ ، ﻳﻤﻜﻦ اﺳﺘﺨﺪام ﻧﺴـﺒﺘﻬﻤﺎ ﻟﺘﺘﺒﻊ ﻣﺘﻰ وأﻳﻦ ﺗﺸﻜﻞ ا ﺎء . ﻋﲆ ﺳﺒﻴﻞ ا ﺜﺎل ﺛﺒﺖ أن ﻫﺬه اﻟﻨﺴﺒﺔ ﰲ ﺑﻌﺾ ﻣﺬﻧﺒﺎت اﻟﻨﻈﺎم اﻟﺸﻤﴘ ﻣﻤﺎﺛﻠﺔ ﻟﺘﻠﻚ ا ﻮﺟﻮدة ﰲ ا ـﺎء ﻋـﲆ اﻷرض ، ﻣﻤﺎ ﻳﺸ إﱃ أن ا ﺬﻧﺒﺎت رﺑﻤﺎ ﺗﻜﻮن ﻗﺪ أوﺻﻠﺖ ا ﺎء إﱃ اﻷرض إن. رﺣﻠﺔ ا ﺎء ﻣﻦ اﻟﻐﻴﻮم إﱃ اﻟﻨﺠﻮم اﻟﻔﺘﻴـﺔ ، ﺛـﻢ ﻻﺣﻘًـﺎ ﻣـﻦ ا ﺬﻧﺒﺎت إﱃ اﻟﻜﻮاﻛـﺐ ﻗـﺪ ﻟﻮﺣﻈـﺖ ﺳـﺎﺑﻘًﺎ وﻟﻜﻦ ﺣﺘﻰ اﻵ ن ﻛـﺎن اﻟـﺮاﺑﻂ ﺑـ اﻟﻨﺠـﻮم اﻟﻔﺘﻴﺔ وا ﺬﻧﺒﺎت ﻣﻔﻘﻮدًا . اﻟﻴﺎﻓﻌﺔ وا ـﺬﻧﺒﺎت ﻣﻔﻘـﻮدًا . ﻳﻘـﻮل ﺗـﻮﺑ : " V883 Orionis ﻫﻮ اﻟﺤﻠﻘﺔ ا ﻔﻘﻮدة ﰲ ﻫﺬه اﻟﺤﺎﻟﺔ ." إن ﺗﺮﻛﻴﺐ ا ﺎء ﰲ اﻟﻘـﺮص ﻣﺸـﺎﺑﻪ ﺟﺪًا ﻟﺘﻜﻮﻳﻦ ا ﺬﻧﺒﺎت ﰲ ﻧ ﻈﺎﻣﻨﺎ اﻟﺸﻤﴘ . ﻫﺬا ﺗﺄﻛﻴﺪ ﻟﻔﻜﺮة أن ا ﺎء ﰲ أﻧﻈﻤﺔ اﻟﻜﻮا ﻛـﺐ ﻗـﺪ ﺗﺸﻜﻞ ﻣﻨﺬ ﻣﻠﻴﺎرات اﻟﺴﻨ ﻗﺒﻞ اﻟﺸـﻤﺲ ﰲ اﻟﻔﻀﺎء ﺑ اﻟﻨﺠﻮم ورﺛﻪ ﻛـﻞ ﻣـﻦ ا ـﺬﻧ ﺒﺎت واﻷرض دون ﺗﻐﻴ ﻧﺴـﺒﻴًﺎ " ﻟﻜـﻦ ﺗﺒـ أن ﻣﺮاﻗﺒﺔ ا ﻴﺎه ﻛﺎﻧـﺖ ﺻـﻌﺒﺔ . ﺗﻘـﻮل ا ﺆﻟﻔـﺔ ا ﺸﺎرﻛﺔ ﻣﺎرﺟﻮت ﻟﻴﻤﻜـﺮ ﻃﺎﻟﺒـﺔ دﻛﺘـﻮراه ــــــــــ ـــــــــــــــــــــــــــ ﺑ ﻤﺮﺻﺪ ﻟﻴﺪن ﰲ ﻫﻮﻟﻨﺪا " : ﻳﺘﻢ ﺗﺠﻤﻴﺪ ﻣﻌﻈـﻢ ا ﻴﺎه ا ﻮﺟﻮدة ﰲ اﻷﻗﺮاص ا ﻜﻮﻧـﺔ ﻟﻠﻜﻮﻛـﺐ ﻛﺠﻠﻴﺪ ﻟﺬﻟﻚ ﻋﺎدةً ﻣـﺎ ﺗﻜـﻮن ﻣﺨ ﺘ ﻔﻴـﺔ ﻋـﻦ أﻋﻴﻨﻨﺎ ." ﻳﻤﻜﻦ اﻛﺘﺸﺎف ا ﻴﺎه اﻟﻐﺎزﻳﺔ ﺑﻔﻀﻞ اﻹﺷﻌﺎع ا ﻨﺒﻌــﺚ ﻣــﻦ اﻟ ﺠﺰﻳﺌــﺎت أﺛﻨــﺎء دوراﻧﻬــﺎ واﻫﺘﺰازﻫﺎ وﻟﻜﻦ ﻫـﺬا أﻛﺜـ ﺮ ﺗﻌﻘﻴـﺪًا ﻋﻨـﺪﻣﺎ ﺘﺠﻤ ﻳ ﺪ ا ﺎء ﺣﻴﺚ ﺗﻜﻮن ﺣﺮﻛﺔ اﻟﺠﺰﻳﺌﺎت أﻛﺜﺮ . ﺗﻘﻴﻴﺪًا ﻳﻤﻜـﻦ اﻟﻌﺜـﻮر ﻋـﲆ ا ﻴـ ﺎه اﻟﻐﺎزﻳـﺔ ﺑﺎﺗﺠﺎه ﻣﺮﻛﺰ اﻷﻗﺮاص ﺑـﺎﻟﻘﺮب ﻣـﻦ اﻟـﻨﺠﻢ ﺣﻴﺚ ﺗﻜﻮن أﻛﺜﺮ دﻓﺌً ﺎ وﻣﻊ ذﻟـﻚ ﻓـﺈن ﻫـﺬه ا ﻨﺎﻃﻖ ا ﻟﻘﺮﻳﺒﺔ ﻣﺨ ﺘ ﻔﻴـﺔ ﺑﻮاﺳـﻄﺔ ﻗـﺮص اﻟﻐﺒﺎر وﻫﻲ أﻳﻀًﺎ أﺻﻐﺮ ﻣﻦ أن ﻳﺘﻢ ﺗﺼﻮﻳﺮﻫﺎ ﺑﺎﺳﺘﺨﺪام اﻟﺘﻠ ﺴﻜﻮﺑﺎت اﻟﺨﺎﺻﺔ ﺑﻨﺎ . ﻟﺤﺴـﻦ اﻟﺤﻆ ﻇﻬﺮ ﻗﺮص V883 Orionis ﰲ دراﺳـﺔ ﺣﺪﻳﺜﺔ ﻟﻴﻜﻮن ﺳـﺎﺧﻨًﺎ ﺑﺸـﻜﻞ ﻏـ ﻋـﺎدي . ﻳﺆدي اﻧﻔﺠﺎر دراﻣﺎﺗﻴﻜﻲ ﻟ ﻠﻄﺎﻗﺔ ﻣﻦ اﻟـﻨﺠﻢ إﱃ ﺗﺴﺨ اﻟﻘﺮص إﱃ درﺟﺔ ﺣﺮارة ﻻ ﻳﻜﻮن ﻓﻴﻬﺎ ا ﺎء ﻋﲆ ﺷﻜﻞ ﺟﻠﻴﺪ ﺑﻞ ﻏﺎز ﻣﻤﺎ ﻳﻤﻜﻨﻨﺎ ﻣﻦ اﻛﺘﺸﺎﻓﻪ " ﻛﻤﺎ ﻳﻘـﻮل ﺗـﻮﺑ . اﺳـﺘﺨﺪم اﻟﻔﺮﻳـﻖ ﻣﺮ ﺻـﺪ ا ـﺎ وﻫـﻲ ﻣﺠﻤﻮﻋـﺔ ﻣـﻦ اﻟﺘﻠﺴـﻜﻮﺑﺎت اﻟﺮادﻳﻮﻳ ـﺔ ﰲ ﺷـﻤﺎل ﺗﺸـﻴﲇ ﺮاﻗﺒـﺔ ا ﻴـﺎه اﻟﻐﺎزﻳـﺔ ﰲ اﻟﻘـﺮص V883 Orionis ﺑﻔﻀـﻞ ﺣﺴﺎﺳـﻴﺘﻪ وﻗﺪرﺗـﻪ ﻋـﲆ ﺗﻤﻴﻴـﺰ اﻟﺘﻔﺎﺻـﻴﻞ اﻟﺼـﻐ ة ﺗﻤﻜﻨـﻮا ﻣـ ﻦ اﻛﺘﺸﺎف ا ﺎء وﺗﺤﺪﻳﺪ ﺗﺮﻛﻴﺒﺘﻪ وﻛﺬﻟﻚ ﺗﻮزﻳﻌﻪ داﺧﻞ اﻟﻘﺮص . وﻗـﺪ وﺟـﺪ اﻟﻔﺮﻳـﻖ أن ﻫـﺬا اﻟﻘﺮص ﻳﺤﺘﻮي ﻋﲆ اﻷﻗﻞ ١٢٠٠ ﺿﻌﻒ ﻛﻤﻴﺔ ا ﺎء ﰲ ﺟﻤﻴﻊ ﻣﺤﻴﻄﺎت اﻷرض . ﻳﺄﻣــﻞ اﻟﻔﺮﻳــﻖ ﰲ ا ﺴــﺘﻘﺒﻞ ﰲ اﺳــﺘﺨﺪام اﻟﺘﻠﺴﻜﻮب اﻟﻜﺒ ﺟﺪاً اﻟﺘﺎﺑﻊ ﺮﺻﺪ اﻷوروﺑﻲ اﻟﺠﻨﻮﺑﻲ وﺟﻬﺎزه ﻣﻦ اﻟ ﺠﻴﻞ اﻷول METIS . ﺳﺘﻜﻮن أداة اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ا ﺘﻮﺳﻄﺔ ﻫﺬه ﻗﺎدرة ﻋﲆ ﺣﻞ ا ﺮﺣﻠﺔ اﻟﻐﺎزﻳﺔ ﻟﻠﻤـﺎء ﰲ ﻫﺬه اﻷﻧﻮاع ﻣﻦ اﻷﻗﺮاص ﻣﻤﺎ ﻳﻌـﺰز ارﺗﺒـﺎط ﻣﺴﺎر ا ﺎء ﻋﲆ ﻃﻮل اﻟﻄﺮﻳـﻖ ﻣـﻦ اﻟﺴـﺤﺐ ا ﻜﻮﻧﺔ ﻟﻠﻨﺠﻮم إﱃ اﻷﻧﻈﻤﺔ اﻟﺸﻤﺴﻴﺔ . وﻳﺨﻠﺺ ﻟﻴﻤﻜﺮ إﱃ اﻟﻘﻮل " : ﺳـﻴﻌﻄﻴﻨﺎ ﻫـﺬا ﻧﻈﺮة أﻛﺜﺮ ﺷﻤﻮﻻً ﻟﻠﺠﻠﻴﺪ واﻟﻐﺎز ﰲ اﻷﻗـﺮاص ا ﻜﻮﻧﺔ ﻟﻠﻜﻮاﻛﺐ ." - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2023 ﺻﻮر ﻣﺮﺻﺪ أﻟﻤﺎ ﻟﻠﻘﺮص اﻟﻤﺤ ﻂ ﺎﻟﻨ ﻢ V883 Orionis ﺗﻮﺿﺢ اﻟﺘﻮز ﻊ ا ـﺎﻧﻲ ﻟﻠﻤـﺎء ﻟﻤ ) ﺴـﺎر ، ﺑﺮﻘـــﺎﻟﻲ ( ــــﺎر ، اﻟﻐ ) وﺳــــﻂ ، أﺧﻀــــﺮ ( أﻛﺴــــ ﺪ اﻟﻜﺮ ــــﻮن وأﺣــــﺎد ) أزرق ، ﻤــــ .( ﻧﻈــــﺮًا ﻷن اﻟﻤــــﺎء ﺘ ﻤـــﺪ ﻋﻨـــﺪ درﺟـــﺎتﺣـــﺮارة أﻋﻠـــﻰ ﻣـــﻦ أول أﻛﺴـــ ﺪ ا ﻟﻜﺮ ـــﻮن ﻓـــﻼ ﻤﻜـــﻦ اﻛﺘﺸـــﺎﻓﮫ إﻻ ﻓـــﻲﺻـــﻮرة ﻏﺎز ـــﺔ أﻗـــﺮ إﻟـــﻰ اﻟــﻨ ﻢ . اﻟﻔﺠـــﻮة اﻟﻮاﺿـــﺤﺔ ﻓـــﻲﺻـــﻮر اﻟﻤـــﺎء وأول أﻛﺴـــ ﺪ اﻟﻜﺮ ـــﻮن ﺗﺮﺟـــﻊ ﻓـــ ﻲ اﻟﻮ اﻗﻊ إﻟﻰ اﻻﻧ ﻌﺎث اﻟﺴﺎﻃﻊ ﻟﻠﻐ ﺎر ﻣﻤﺎ ﻘﻠﻞ ﻣﻦ اﻧ ﻌﺎث اﻟﻐﺎز .