Free Astronomy Magazine May-June 2023 ARABIC VERSION

MAY-JUNE 2023 signed to hunt for new asteroids — in fact, they were calibration im- ages of the main belt asteroid (10920) 1998 BC1, which as- tronomers discovered in 1998. The observations were conducted to test the performance of some of MIRI’s filters, but the calibration team considered them to have failed for technical reasons due to the brightness of the target and an offset telescope pointing. Despite this, the data on asteroid 10920 were used by the team to establish and test a new technique to con- strain an object’s orbit and to esti- mate its size. The validity of the method was demonstrated for as- teroid 10920 using the MIRI obser- vations combined with data from ground-based telescopes and ESA’s Gaia mission. In the course of the analysis of the MIRI data, the team found the smaller interloper in the same field of view. The team’s results suggest the object measures 100–200 me- ters, occupies a very low-inclination orbit, and was located in the inner main-belt region at the time of the Webb observations. “Our results show that even ‘failed’ Webb observations can be scientif- ically useful, if you have the right mindset and a little bit of luck,” elaborated Müller. “Our detection lies in the main asteroid belt, but Webb’s incredible sensitivity made it possible to see this roughly 100- meter object at a distance of more than 100 million kilometers.” The detection of this asteroid — which the team suspects to be the smallest observed to date by Webb and one of the smallest detected in the main belt — would, if con- firmed as a new asteroid discovery, have important implications for our understanding of the formation and evolution of the solar system. Current models predict the occur- rence of asteroids down to very small sizes, but small asteroids have been studied in less detail than their larger counterparts owing to the difficulty of observing these ob- jects. Future dedicated Webb obser- vations will allow astronomers to study asteroids smaller than 1 kilo- meter in size. What’s more, this result suggests that Webb will also be able to serendipitously contribute to the detection of new asteroids. The team suspects that even short MIRI observations close to the plane of the solar system will always include a few asteroids, most of which will be unknown objects. In order to confirm that the object detected is a newly discovered as- teroid, more position data relative to background stars is required from follow-up studies to constrain the object’s orbit. “This is a fantastic result which highlights the capabilities of MIRI to serendipitously detect a previ- ously undetectable size of asteroid in the main belt,” concluded Bryan Holler, Webb support scientist at the Space Telescope Science Insti- tute in Baltimore, Maryland. “Re- peats of these observations are in the process of being scheduled, and we are fully expecting new asteroid interlopers in those images.”  ﺟﺮام ﻣﻦ اﻷ اﻟﺠﺪﻳﺪة ﺑﺎﺳﺘﺨﺪام ﻫﺬه اﻷداة إن . أرﺻﺎد ﺗﻠﺴﻜﻮب وﻳﺐ ﻫﺬه ا ﻨﺸﻮرة ﰲ ﻣﺠﻠ ﺔ ﻋﻠـﻢ اﻟﻔﻠـﻚ واﻟﻔﻴﺰﻳـﺎء اﻟﻔﻠﻜﻴــﺔ ﻟـﻢ ﺗﻜــﻦ ﻣﺼﻤﻤﺔ ﻟﻠﺒﺤـﺚ ﻋـﻦ ﻛﻮﻳﻜﺒـﺎت ﺟﺪﻳـﺪة ﰲ اﻟﻮاﻗﻊ ﻛﺎﻧﺖ اﺳﺎﺳﺎً ﺻﻮر ﻣﻌﺎﻳﺮة ﻟﻜﻮﻳﻜـﺐ اﻟﺤــﺰام اﻟﺮﺋﻴــ )ﴘ ـ 10920 ( 1992 BC1 واﻟﺬي اﻛﺘﺸﻔﻪ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﰲ ﻋﺎم ١٩٩٨ . ﺗ ـﻢ إﺟ ـﺮاء اﻻرﺻــﺎد ﻻﺧﺘﺒ ـﺎر أداء ﺑﻌ ـﺾ ﻣﺮﺷﺤﺎت ) ﻛﺎﻣ ا MIRI ( ﻟﻜﻦ ﻓﺮﻳﻖ ا ﻌﺎﻳﺮة اﻋﺘﱪﻫﺎ ﻗـﺪ ﻓﺸـﻠﺖ ﻷﺳـﺒﺎب ﻓﻨﻴـﺔ ﺑﺴـﺒﺐ ﺳﻄﻮع اﻟﻬﺪف وﺗﻠﺴﻜﻮب اﻹز اﺣﺔ . ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ ذﻟﻚ اﺳﺘﺨﺪم اﻟﻔﺮﻳﻖ ﺑﻴﺎﻧـﺎت اﻟﻜﻮﻳﻜـﺐ 10920 ﻹﻧﺸـﺎء واﺧﺘﺒـﺎر ﺗﻘﻨﻴـﺔ ﺟﺪﻳﺪة ﻟﺘﻘﻴﻴﺪ ﻣﺪار ﺟﺴﻢ ﻣﺎ وﺗﻘﺪﻳﺮ ﺣﺠﻤﻪ . ﺗﻢ إﺛﺒﺎت ﺻـﺤﺔ ﻫـﺬه اﻟﻄﺮﻳﻘـﺔ ﻟﻠﻜﻮﻳﻜـﺐ 10920 ﺑﺎﺳﺘﺨﺪام أرﺻـﺎد ﻛـﺎﻣ ا (MIRI) ﺟﻨﺒًﺎ إﱃ ﺟﻨﺐ ﻣﻊ اﻟﺒﻴﺎﻧﺎت ﻣﻦ اﻟﺘﻠﺴـﻜﻮﺑﺎت اﻷرﺿـﻴﺔ وﻣﻬﻤـﺔ ا ﺮﻛﺒـﺔ ا " ﻏﺎﻳـﺎ " ﻟﺘﺎﺑﻌـﺔ ﻟﻮﻛﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑﻴﺔ . ﰲ ﺳﻴﺎق ﺗﺤﻠﻴﻞ ﺑﻴﺎﻧﺎت ﻛـﺎﻣ ا MIRI وﺟـﺪ اﻟﻔﺮﻳـﻖ ا ﺘـﺪاﺧﻞ اﻷﺻـﻐﺮ ﰲ ﻧﻔـﺲ ﻣﺠـﺎل اﻟﺮؤﻳﺔ . ﺗﺸـ ﻧﺘـﺎﺋﺞ اﻟﻔﺮﻳـﻖ إﱃ أن ﺣﺠـﻢ اﻟﺠﺴــﻢ ١٠٠ - ٢٠٠ وﻳ ﻣــﱰ ﺤﺘــﻞ ﻣــﺪارًا اﻟﺠﺴــﻢ ١٠٠ - ٢٠٠ وﻳ ﻣــﱰ ﺤﺘــﻞ ﻣــﺪارًا ﻣﻨﺨﻔﺾ ا ﻴﻞ ﻟﻠﻐﺎﻳﺔ وﻛﺎ ن ﻳﻘﻊ ﰲ ﻣﻨﻄﻘـﺔ اﻟﺤﺰام اﻟﺮﺋ ﻴﴘـ اﻟﺪاﺧﻠﻴـﺔ ﰲ وﻗـﺖ أرﺻـﺎد ﺗﻠﺴﻜﻮب . وﻳﺐ أوﺿﺢ ﻣﻮﻟﺮ " : ﺗُﻈﻬﺮ ﻧﺘﺎﺋﺠﻨﺎ أﻧﻪ ﺣﺘﻰ ارﺻﺎد ﺗﻠﺴـﻜﻮب " وﻳـﺐ اﻟﻔﺎﺷـﻠﺔ ﻳﻤ" ﻜﻦ أن ﺗﻜﻮن ﻣﻔﻴﺪة ﻋﻠﻤﻴًﺎ إذا ﻛﺎن ﻟـﺪﻳﻚ ا ﻟﻌﻘﻠﻴ ـﺔ اﻟﺼــﺤﻴﺤﺔ وﻗﻠــﻴﻼً ﻣــﻦ اﻟﺤــﻆ . اﻛﺘﺸــﺎﻓﻨﺎ ﻳﻜﻤــﻦ ﰲ ﺣــﺰام اﻟﻜﻮﻳﻜﺒــﺎت اﻟﺮﺋﻴ ﴘـ ﻟﻜـﻦ ﺣﺴﺎﺳـﻴﺔ ﺗﻠﺴـﻜﻮب وﻳـﺐ ﺟﻌﻠﺖ ﻣﻦ ا ﻤﻜﻦ رؤﻳﺔ ﻫﺬا اﻟﺠﺮم اﻟﺬي ﻳﺒﻠﻎ ﻃﻮﻟﻪ ١٠٠ ﻣﱰ ﺗﻘﺮﻳﺒًﺎ ﻋﲆ ﻣ ﺴﺎﻓﺔ ﺗﺰﻳﺪ ﻋـﻦ ١٠٠ ﻣﻠﻴ ـﻮن ﻛﻴﻠ ـﻮﻣﱰ . إن اﻛﺘﺸــﺎف ﻫــﺬا اﻟﻜﻮﻳﻜﺐ اﻟﺬي ﻳﺸﺘﺒﻪ اﻟﻔﺮﻳﻖ ﰲ أﻧﻪ اﻷﺻـﻐﺮ اﻟﺬي رﺻﺪه ﺗﻠﺴﻜﻮب وﻳﺐ ﺣﺘﻰ اﻵن وواﺣﺪ اً ﻣﻦ أﺻﻐﺮ اﻟﻜﻮﻳﻜﺒﺎت اﻟﺘﻲ ﺗـﻢ اﻛﺘﺸـﺎﻓﻬﺎ ﰲ اﻟﺤﺰام اﻟﺮﺋﻴ ـ ﻪ ﴘ ﺳﻴﻜﻮن ﻟ إذا ﺗـﻢ ﺗﺄ ﻛﻴـﺪه ﻋﲆ أﻧﻪ اﻛﺘﺸﺎف ﻛﻮﻳﻜﺐ ﺟﺪﻳﺪ آﺛـﺎر ﻣﻬﻤـﺔ ﻋﲆ ﻓﻬﻤﻨﺎ ﻟﻠﻜﻮﻳﻜﺐ و ﺗﻜﻮﻳﻦ وﺗﻄﻮر اﻟﻨﻈﺎم اﻟﺸﻤ .ﴘـ ﺗﺘﻨﺒﺄ اﻟﻨﻤـﺎذج اﻟﺤﺎﻟﻴـﺔ ﺑﺤـﺪوث اﻟﻜﻮﻳﻜﺒﺎت وﺻﻮﻻً إﱃ أﺣﺠـﺎم ﺻـﻐ ة ﺟـﺪًا وﻟﻜﻦ ﺗﻤـﺖ دراﺳـﺔ اﻟﻜﻮﻳﻜﺒـﺎت اﻟﺼـﻐ ة ﺑﺘﻔﺎﺻﻴﻞ أﻗﻞ ﻣﻦ ﻧﻈ اﺗﻬـﺎ اﻷﻛـﱪ ﺣﺠﻤًـﺎ ﻧﻈ ـﺮًا ﻟﺼـﻌﻮﺑﺔ ﻣﺮاﻗﺒ ـﺔ ﻫ ـ ﺬه اﻷﺟﺴ ـﺎم . ﻣﻦ ﻧﻈ اﺗﻬﺎ اﻷﻛﱪ ﺣﺠﻤًـﺎ ﻧﻈـﺮًا ﻟﺼـﻌﻮﺑﺔ ﻣﺮاﻗﺒـﺔ ﻫـﺬه اﻷﺟﺴـﺎم . ﺳﺘﺴـﻤﺢ أرﺻـﺎد ﺗﻠﺴﻜﻮب وﻳﺐ ا ﺴﺘﻘﺒﻠﻴﺔ ﺑﺪراﺳﺔ اﻟﻜﻮﻳﻜﺒﺎت اﻟﺘﻲ ﻳﻘﻞ ﺣﺠﻤﻬﺎ ﻋﻦ ﻛﻴﻠﻮﻣﱰ واﺣﺪ . اﺿﺎﻓﺔ ﺗﺸـ ﻫـﺬه اﻟﻨﺘﻴﺠـﺔ ﺄن ﺑـ ﺗﻠﺴـﻜﻮب وﻳـﺐ ﺳـﻴﻜﻮن ﻗ ـﺎدرًا أﻳﻀًـﺎ ﻋ ـﲆ ا ﺴ ـﺎﻫﻤﺔ ﰲ اﻛﺘﺸﺎف اﻟﻜﻮﻳﻜﺒﺎ . ت اﻟﺠﺪﻳﺪة ﻳﺸﻚ اﻟﻔﺮﻳـﻖ أن أرﺻﺎد ﻛﺎﻣ ا ) MIRI ( اﻟﻘﺼ ة اﻟﻘﺮﻳﺒـﺔ ﻣﻦ ﻣﺴﺘﻮى اﻟﻨﻈﺎم اﻟﺸﻤﴘﺳﺘﺸﻤﻞ داﺋ ﻤًـﺎ اً ﻋﺪد ﻗﻠﻴﻼً ﻣﻦ اﻟﻜﻮﻳﻜﺒﺎت و ﺳﻴﻜﻮن ﻣﻌﻈﻤﻬﺎ أﺟﺴﺎﻣًﺎ ﻏ ﻣﻌﺮوﻓﺔ و ﻣﻦ أﺟﻞ اﻟﺘﺄﻛﺪ ﻣﻦ أن اﻟ ﺠﺴﻢ اﻟﺬي ﺗﻢ اﻛﺘﺸﺎ ﻓﻪ ﻫﻮ ﻛﻮﻳﻜـﺐ ﻳﻠـﺰم ﺗﻮﻓ ا ﺰﻳﺪ ﻣﻦ اﻟ ﺒﻴﺎﻧـﺎت ا ﺘﻌﻠﻘـﺔ ﺑﻨﺠـﻮم اﻟﺨﻠﻔﻴﺔ ﻣﻦ دراﺳﺎت ا ﺘﺎﺑﻌﺔ ﻟﺘﻘﻴﻴـﺪ ﻣـﺪار اﻟﺠﺴﻢ . وﺧﻠﺺ ﺑﺮاﻳﺎن ﻫﻮﻟﺮ ﻣﻦ ﻣﻌﻬﺪ ﻋﻠﻮم ﺗﻠﺴﻜﻮب اﻟﻔﻀﺎء ﰲ ﺑـﺎﻟﺘﻴﻤﻮر إﱃ أن ﻫـﺬه " ﻧﺘﻴﺠﺔ راﺋﻌﺔ و ﺗﺴـﻠﻂ اﻟﻀـﻮء ﻋـﲆ ﻗـﺪرات ) ﻛﺎﻣ ا MIRI ( ﻋﲆ اﻛﺘﺸﺎفﺣﺠﻢ اﻟﻜﻮﻳ ﻜﺐ اﻟﺬي ﻟﻢ ﻳﻜﻦ ﻣﻦ ا ﻤﻜﻦ اﻛﺘﺸﺎﻓﻪ ﺳـﺎﺑﻘًﺎ ﰲ اﻟﺤﺰام اﻟﺮﺋﻴ . ﴘـ وﻋﲆ ﻛﻞ ﺣﺎل ﻓـﺎن إﻋـﺎدة ﻫﺬه اﻷ رﺻﺎد ﻗﻴﺪ اﻹﺟﺮاء وﻣﻦ ا ﺘﻮﻗﻊ ﻮد وﺟ ﺑﻌﺾ اﻟ ﻜﻮﻳﻜﺒﺎت اﻟ ﺠﺪﻳﺪة ﰲ ﺗﻠﻚ اﻟﺼﻮر . - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2023