Free Astronomy Magazine January-February 2024 ARABIC VERSION

Webb observed the WASP-17 system for nearly 10 hours, collecting more than 1,275 brightness measurements of 5- to 12-micron mid-infrared light as the planet crossed its star. By sub- tracting the brightness of individual wavelengths of light that reached the telescope when the planet was in front of the star from those of the star on its own, the team was able to calculate the amount of each wavelength blocked by the planet’s atmosphere. What emerged was an unexpected “bump” at 8.6 microns, a feature that would not be ex- pected if the clouds were made of magnesium silicates or other possible high-temperature aerosols like alu- minum oxide, but which makes per- fect sense if they are made of quartz. While these crystals are probably similar in shape to the pointy hexag- onal prisms found in geodes and gem shops on Earth, each one is only about 10 nanometers across – one-millionth of one centimeter. “Hubble data actually played a key role in constraining the size of these particles,” explained co-author Nikole Lewis of Cornell University, who ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 24 ﻜﺸﻒ ا ﻃ ﻒ ﻟ ﻮﻛﺐ اﻟﻨ ﻤﻲ اﻟﻌﻤﻼق اﻟﻐﺎزي اﻟﺴﺎﺧﻦ WASP-17 b اﻟﺘﻘﻄﺘﮫ ، اﻟﺬ أداة )( ﻣ ي) ﻟﻸﺷـﻌﺔ ﺗﺤـﺖ ا ﻤـﺮاء اﻟﻤﺘﻮﺳـﻄﺔ ﻓـﻲ ( 12-13 ﻣـﺎرس 2023 ، ﻋﻦ أول دﻟﻴﻞ ﻋﻠ ﻰوﺟﻮد اﻟ ﻮارﺰ ) اﻟﺴ ﻠﻴ ﺎ اﻟ ﻠﻮر ﺔ، (SiO2 ﻏﻴﻮم ﻓﻲ ﻮﻛﺐ ﻧ ﻤﻲ . ـﺎس اﻟﺘﻐـ ﻓـﻲﺳـﻄﻮع ﺗـﻢ إﺟـﺮاء اﻟﺘﺤﻠﻴـﻞ اﻟﻄ ﻔـﻲﻋـﻦ ﻃﺮ ـﻖ ﻗ 28 ﻧﻄﺎﻗـ ﺎ ﻣـﻦ اﻟﻄـﻮل اﻟﻤـﻮﺟﻲ ﻟﻸﺷـﻌﺔ ﺗﺤـﺖ اﻟـ ـ ﻤ ﺮاء اﻟﻤﺘﻮﺳـﻄﺔ أﺛﻨـﺎء ﻋﺒــﻮراﻟ ﻮﻛـﺐ أﻣـﺎم ﻧ ﻤـﮫ . رﺻــﺪ ﺗﻠﺴـ ﻮب ـﺐ ﻧﻈـﺎم و WASP-17 ـﺎف ﺎﺳـﺘﺨﺪام ﻣﻄ ( ﻣ ي) ﻟﻤﺪة 10 ﺳ ﺎﻋﺎت ﺗﻘﺮ ًﺎ، و ﻤﻊ أﻛ ﻣﻦ 1275 ﻗ ﺎﺳًﺎ ﻗﺒﻞ وأﺛﻨﺎء و ﻌﺪ اﻟﻌﺒﻮر . ﺎﻟﻨﺴ ﺔ ﻟ ﻞ ﻃﻮل ﻣﻮﺟﻲ ﻳﺤﺠﺒﻬـﺎ اﻟﻐـﻼف ـﺔ اﻟﻀـﻮء اﻟـ ﺗﻢ ﺣﺴـﺎب ﻤ ـ اﻟـ ﺠﻮي ﻟﻠ ﻮﻛــﺐ ) اﻟـﺪواﺋﺮاﻟﺒ ﻀــﺎء ( اﻟﻐــﻼف اﻟـ ﻋــ ــﺔ اﻟـ ﻋــﻦ ﻃﺮ ـﻖﻃــﺮح اﻟ ﻤ ـ ــﺔ اﻟﻤﻨ ﻌﺜـﺔ أﺻـﻼً ﻣــﻦ اﻟـﻨ ﻢ ﺠﻮي ﻣــﻦ اﻟ ﻤ . ـ ﻌــﺪ اﻟــ ﺨﻂ اﻷرﺟـﻮاﻧﻲ اﻟﺼـﻠ ﺐ ﻫـﻮ اﻟﻨﻤــﻮذج اﻷﻧﺴــﺐ ﻟﺒ ﺎﻧــﺎ ــﺐ وﻫﺎﺑـﻞ وﺳــﺒ ﺰ ت اﻟﺘﻠﺴــ ﻮ ﺎت و . ــﺔ ﺗــ اوح ﻣــﻦ ﺗﻐﻄــﻲ ﺑ ﺎﻧــﺎتﻫﺎﺑــﻞ وﺳــﺒ رأﻃــﻮال ﻣﻮﺟ 0.34 إﻟــﻰ 4.5 ﻣ ﻜــﺮون وﻻ ﺗﻈﻬــﺮﻓــﻲ ــﺎﻧﻲ اﻟﺮﺳــﻢ اﻟﺒ (. ــﻒ ﻣــ ة واﺿـــﺤﺔ ﺗ ﻠــﻎ ﺣــﻮاﻟﻲ ُﻈﻬـــﺮ اﻟﻄ 8.6 ﻣ ﻜـــﺮون ﻌﺘﻘــﺪ ﻋﻠﻤـــﺎء اﻟﻔﻠــﻚ أﻧﻬــﺎ ﻧﺎ ﻤـــﺔ ﻋــﻦ اﻣﺘﺼــﺎصﺟﺰ ﺌـــﺎت اﻟﺴــ ﻠﻴ واﻟــ ﺎ ﻟــ ﻌﺾﺿـــﻮء ﻤــﺮ ﻋــ اﻟﻐــﻼف اﻟــ اﻟﻨﺠــﻮم اﻟــﺬ ـ . ﺠﻮي ـ ُﻈﻬــﺮ اﻟــ ــﻒﺳـﻴ ﺪو ﻫــﺬا اﻟــ ﺨﻂ اﻷﺻــﻔﺮ اﻟﻤﺘﻘﻄــﻊ ﻛ ـ ــﻒ اﻹرﺳـﺎل إذا ﺎﻧــﺖ ﺠﺰء ﻣــﻦ ﻃ اﻟﻐﻴــﻮم اﻟﻤﻮﺟــﻮدة ﻓــﻲ اﻟﻐــﻼف ـ اﻟـ ﺠﻮي ﻟ ﻠ ﻮﻛـﺐ WASP-17 b ﻻ ﺗﺤﺘـﻮيﻋﻠـﻰ SiO2 ـﺪ ـﺘﻢ ﻓﻴﻬـﺎ ﺗﺤﺪ وﻫـﺬﻩ ﻫـﻲ اﻟﻤـﺮة اﻷوﻟـﻰ اﻟـ SiO2 ﻓـﻲ ﻮﻛـﺐ ﻧ ﻤـﻲ واﻟﻤـﺮة اﻷ ـﺘﻢ ﻓﻴﻬـﺎ وﻟـﻰ اﻟـ ﺗﺤﺪ ﺪ أي ﻧﻮع ﻣﺤﺪد ﻣﻦ اﻟ ﻐﻴﻮم ﻓﻲ ﻮﻛﺐ ﻧ ﻤﻲ ﻋﺎﺑﺮ أﻣﺎم ﻧ ﻤﮫ . ر ﺻ ـــﺪ ﺗﻠﺴ ـــﻜﻮب ﺟ ـــﻴﻤﺲ وﻳ ـــﺐ ﻧﻈـــﺎم WASP-17 ـــﺪة 10 ﺳـــﺎﻋﺎت ﺗﻘﺮﻳﺒـــﺎ وﺟﻤـــﻊ أﻛﺜـــﺮ ﻣـــﻦ 1275 ﻗﻴﺎﺳــﺎً ﻟﺴــﻄﻮ ع ﺿــﻮء اﻷﺷــﻌﺔ ﺗﺤــﺖ اﻟﺤﻤــــﺮاء ا ﺘﻮﺳــــﻄﺔ ﻣــــﻦ 5 إﱃ 12 ﻣﻴﻜــﺮون أﺛﻨــﺎء ﻋﺒــﻮر اﻟﻜﻮﻛــﺐ أﻣــﺎم ﻧﺠﻤــﻪ وﻣـــﻦ ﺧـــﻼل ﻃــﺮح ﺳــﻄﻮع اﻷﻃــﻮال ا ﻮﺟﻴ ـﺔ اﻟﻔﺮدﻳ ـﺔ ﻟﻠﻀ ـﻮء اﻟﺘ ـﻲ ــ وﺻﻠﺖ إﱃ اﻟﺘﻠﺴﻜﻮب ﻋﻨـﺪﻣﺎ ﻛـﺎن اﻟﻜﻮﻛـﺐ أﻣﺎم اﻟﻨﺠﻢ ﻣـﻦ ﺳـﻄﻮع اﻷﻃـﻮال ا ﻮﺟﻴـﺔ اﻟﻔﺮدﻳﺔ ﻟﻠﻀﻮء، ﺗﻤﻜﻦ اﻟﻔﺮﻳﻖ ﻣـﻦ ﺣﺴـﺎب ﻣﻘﺪار ﻛـ ﻞ ﻃـﻮل ﻣـﻮﺟﻲ ﻳﺤﺠﺒـﻪ اﻟﻐـﻼف اﻟﺠﻮي ﻟﻠﻜﻮﻛﺐ . ﻣﺎ ﻇﻬﺮ ﻛـﺎن ﻋﺒـﺎرة ﻋـﻦ " ﻧﺘﻮء " ﻏ ﻣﺘﻮﻗﻊ ﻋﻨﺪ 8.6 ﻣﻴﻜﺮون وﻫـﻲ ﻣﻴﺰة ﻟﻢ ﺗﻜـﻦ ﻣﺘﻮﻗﻌـﺔ إذا ﻛﺎﻧـﺖ اﻟﺴـﺤﺐ ﻣﻜﻮﻧﺔ ﻣﻦ ﺳﻴﻠﻴﻜﺎت ا ﻐﻨﻴﺴـﻴﻮم أو ﻏ ﻫـﺎ ـ ـــ ﻣﻦ اﻟﻬﺒﺎء اﻟﺠﻮي ا ﺤﺘﻤﻞ ذو درﺟﺔ اﻟﺤﺮارة اﻟﻌﺎﻟﻴﺔ ﻣﺜﻞ أﻛﺴﻴﺪ اﻷﻟﻮﻣﻨﻴﻮم وﻟﻜﻨﻬﺎ ﺗﺒـﺪو ﻣﻨﻄﻘﻴﺔ ﺗﻤﺎﻣﺎً إذا ﻛﺎﻧـﺖ ﻣـﻦ اﻟﻜـﻮارﺗﺰ . أن ﻫﺬه اﻟﺒﻠﻮرات رﺑﻤﺎ ﺗﻜﻮن ﻣﺸﺎﺑﻬﺔ ﰲ اﻟﺸﻜﻞ ﻟﻠﻤﻨﺸﻮرات اﻟﺴﺪاﺳﻴﺔ ا ﺪﺑﺒـﺔ ا ﻮﺟـﻮدة ﰲ اﻟﺠﻴﻮد وﻣﺤﻼت اﻷﺣﺠﺎر اﻟﻜﺮﻳﻤﺔ ، ﻓﺈن ﻛـﻞ واﺣﺪة ﻣﻨﻬﺎ ﻳﺒﻠﻎ ﻋﺮﺿﻬﺎ ﺣﻮاﱄ 10 ﻧـﺎﻧﻮﻣﱰ – ﻓﻘﻂ ﺟﺰء ﻣﻦ ﻣﻠﻴﻮن ﻣﻦ ﺳﻨﺘﻴﻤﱰ واﺣﺪ . - ﻳﻨﺎﻳﺮ ﻓﺒﺮﺍﻳﺮ 2 0 2 4