Free Astronomy Magazine March-April 2025 ARABIC VERSION

could have prevented dust beyond itsorbitfromcreatingnewplanets, leavinguswithjustabeltofdebris. This debris, though, is a hidden space treasure. Today,theKuiperBeltisacollection ofdustyandicyspacerocks,ranging from dust grains and pebbles to comets and dwarf planets. From a few millimeters to kilometers in di- ameter, many of these objects have changed little since their formation. Frozen (literally) in time, these are remnants of the early stages of the Solar System and tell us a lot about its initial properties. Belts of debris like the Kuiper Belt exist in other planetary systems,too. They are broadly known as “planetesimalbelts”sincetheob- jectswithinthemhavethepotential to coalesce to form planets, or “ex- ocomet belts” since they usuallyhide comets (icy planetesimals) within them. But how can we ob- serve these belts? Given their size, finding exocomet beltsshouldbeeasyatfirstglance. However, belts have been difficult to observe and image. The reason behindthisistheirtemperature.The objects lying within an exocomet beltareveryfarfromtheirhoststar, andthus,theyareextremelycold.In theKuiperbelt,temperaturesrange from-250to-150degreesCelsius.At theselowtemperatures,beltsonly shine at long wavelengths, making themdifficulttoobserveformost— but not all — telescopes. MARCH-APRIL2025 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 23 اﻟﻜﺒ ة ﻣﺜﻞ ﻧﺒﺘﻮن رﺑﻤﺎ ﻣﻨﻊ اﻟﻐ ﺒﺎر ﺧـﺎرج ﻣﺪاره ﻣﻦ ﺗﻜﻮﻳﻦ ﻛﻮاﻛﺐ ﺟﺪﻳﺪة ﻣﻤـﺎ ﺗـﺮك ﻟﻨﺎ ﺣﺰاﻣ ﺎً ﻣﻦ اﻟﺤﻄﺎم وﻣﻊ ذﻟﻚ ﻓـﺈن ﻫـﺬا اﻟﺤﻄﺎم ﻫﻮ ﻛﻨﺰ ﻓﻀﺎﺋﻲ . اﻟﻴﻮم ﻳﺘﺄﻟﻒ ﺣ ﺰام ﻛﺎﻳﱪ ﻣﻦ ﻣﺠﻤﻮﻋﺔ ﻣـﻦ اﻟﺼـﺨﻮر ﻓﻀـﺎﺋﻴﺔ ﺗﺮاﺑﻴ ـﺔ ﺗ ـﱰاوح ﻣ ـﻦ ﺣﺒﻴﺒ ـ ﺎت اﻟﻐﺒ ـﺎر واﻟﺤ ـ ـ ﴡ إﱃ ا ـﺬﻧﺒﺎت واﻟﻜﻮاﻛﺐ اﻟﻘﺰﻣﺔ ﻣﻦ ﺑﻀﻌﺔ ﻣ ﻠﻠﻴﻤﱰات إﱃ ﻛﻴﻠﻮﻣﱰات ﰲ اﻟﻘﻄﺮ ﻟﻢ ﻳﺘﻐـ اﻟﻜﺜـ ﻣـﻦ ﻫﺬه اﻷﺟﺴﺎم ﻣﻨﺬ ﺗﻜﻮﻳﻨﻬﺎ . ﻫﺬه اﻷﺟﺴـﺎم ﺘا ( ﺎً ﺣﺮﻓﻴـ ) ﺠﻤـﺪة ﰲ اﻟﻮﻗـﺖ ﻫـﻲ ﺑﻘﺎﻳـﺎ ا ﺮاﺣﻞ ا ﺒﻜﺮ ة ﻣﻦ اﻟﻨﻈﺎم اﻟﺸﻤﴘوﺗﺨﱪﻧﺎ اً ﻛﺜ ﻋﻦ ﺧﺼﺎﺋﺼﻪ اﻷوﻟﻴﺔ . ﺗﻮﺟﺪ أﺣﺰ ﻣﺔ ﻣﻦ اﻟﺤﻄﺎم ﻣﺜﻞ ﺣﺰام ﻛـ ﺎﻳﱪ ﰲ أﻧﻈﻤﺔ ﻛﻮﻛﺒﻴﺔ أﺧﺮى أﻳﻀًﺎ وﻫﻲ ﻣﻌﺮوﻓﺔ ﻋﲆ ﻧﻄﺎق واﺳﻊ ﺑﺎﺳﻢ " أﺣﺰﻣـﺔ اﻟﻜﻮاﻛـﺐ اﻟﺼﻐ ة " ﻷن اﻷﺟﺴـﺎم ا ﻮﺟـﻮدة داﺧﻠﻬـﺎ ـــ ﻟﺪﻳﻬﺎ اﻟﻘﺪرة ﻋـﲆ اﻻﻧـﺪﻣﺎج ﻣـﻊ ﺑﻌﻀـﻬﺎ اﻟــﺒﻌﺾ ﻟﺘﻜــﻮﻳﻦ اﻟﻜﻮاﻛــﺐ " أو أﺣﺰﻣــﺔ ا ــﺬﻧﺒﺎت اﻟﻨﺠﻤﻴ ـﺔ " ﻷﻧﻬ ـﺎ ﺗﺨﻔــﻲ ﻋــﺎدةً ا ــﺬﻧﺒﺎت ا) ﻟﻜﻮاﻛــﺐ اﻟﺼـﻐ ة اﻟﺠﻠﻴﺪﻳـﺔ ( داﺧﻠﻬﺎ وﻟﻜﻦ ﻛﻴﻒ ﻳﻤﻜﻨﻨـﺎ اﻟﻘﻴـﺎم ﺑﺮﺻـﺪ ﻫﺬه اﻷﺣﺰﻣﺔ؟ اً ﻧﻈﺮ ﻟﺤﺠﻤﻬﺎ ﻓﺈن اﻛﺘﺸﺎف أﺣﺰﻣﺔ ا ﺬﻧﺒﺎت اﻟ ﻨﺠﻤﻴﺔ ﻳﺒﺪو ﺳﻬﻼً وﻟﻜﻦ ﻣﻦ اﻟﺼﻌﺐ رﺻﺪ ا ﻷﺣﺰﻣﺔ وﺗﺼﻮﻳﺮﻫﺎ ﺴﺒﺐ ﺑ درﺟﺔ ﺣﺮارﺗﻬـﺎ ﻓ ﺎﻷﺟﺴﺎم داﺧﻞ ﺣـﺰام ا ـﺬﻧﺒﺎت اﻟﻨﺠﻤﻴـﺔ ﺗﺒﻌﺪ ﻣﺴﺎﻓﺔ ﺷﺎﺳﻌﺔ اً ﺟﺪ ﻋﻦ ﻧﺠﻤﻬﺎ ﻟـﺬﻟﻚ ﻓﻬﻲ ﺑﺎردة ﻟﻠﻐﺎﻳﺔ . ﺗﱰاوح درﺟﺎت اﻟﺤﺮارة ﰲ ﺣﺰام ﻛﺎﻳﱪ - ﻣـﻦ 250 - إﱃ 150 درﺟـﺔ و ﻣﺌﻮﻳﺔ ﻋﻨﺪ ﻫﺬه اﻟﺤﺮارة ا ﻨﺨﻔﻀﺔ ﺗﺘـﺄﻟﻖ اﻷﺣﺰﻣﺔ ﻓﻘﻂ ﺑﺄﻃﻮال ﻣﻮﺟﻴﺔ ﻃﻮﻳﻠﺔ ﻣﻤـﺎ ﻳﺠ ﻌــﻞ ﻣــﻦ اﻟﺼــﻌﺐ رﺻــﺪﻫﺎ ﺑ ﻤﻌﻈــﻢ اﻟﺘﻠﺴﻜﻮﺑﺎت وﻟﻜﻦ ﻟﻴﺲ ﻛﻠﻬﺎ . رﺳــــﻢ ﺗﺨ ﻠــــﻲ ﻟـــــ ــــﺎﻳ ﺤﺰام ــــﺎرة ﻋــــﻦ وﻫــــﻮ ﻋ أﺟﺴـﺎمﺻـﺨﺮ ﺔ ﻛﺜ ﻔـﺔ ﺗﻘـﻊ ﺧـﺎرج ﻣـﺪارﻧ ﺘــﻮن . [ESO/M. Kornmesser] ﺃﺑﺮﻳﻞ - ﻣﺎﺭﺱ 2 0 2 5