Free Astronomy Magazine September-October 2023 ARABIC VERSION

I tostars. Moreover, the ring structures are less distinct than those seen in the protoplanetary disks. It was also found that the dust (building blocks of planets) in many disks, is not set- tled in the disk midplane. Rather the dust is aloft, above the disk midplane, making the disks ap- pear thick in the vertical direction. In more-evolved disks, in contrast, the dust settles down in the midplane thereby making them appear much thinner. “We did not expect to see such clear differences between disks around protostars and more-evolved disks,” says Ohashi. John Tobin, a Co- PI of the program at the National Radio Astronomical Observatory (USA) adds “Our results suggest that disks around protostars are not fully ready for planet formation. We be- lieve that the actual formation of the planetary system progresses rap- idly in the 100,000 years to 1,000,000 years after star formation begins.” Jes Jørgensen, the other Co-PI of the program at the Niels Bohr Institute of University of Copenhagen (Den- mark) also mentions the importance of international cooperation in plan- ning and implementing such a large- scale program. “There are 37 re- searchers from 15 research institutes participating in the international re- search group that promoted this re- search. In addition, about half of them are graduate students or young researchers who have recently ob- tained their Ph.D. This research gives many young researchers the oppor- tunity to participate in large-scale in- ternational programs, and it can be said that this program plays a major role in nurturing future research and collaboration.”    - ﺳﺒﺘﻤﺒﺮ ﺃﻛﺘﻮﺑﺮ 2 0 2 3 اﻟﻜﻮاﻛﺐ اﻷوﻟﻴﺔ وﻗﺪ وﺟﺪ أﻳﻀـﺎً أن اﻟﻐﺒـﺎر ) وﺣﺪات ﺑﻨﺎء اﻟﻜﻮاﻛﺐ ( ا ﻮﺟﻮدة ﰲ اﻟﻌﺪﻳـﺪ ﻣﻦ اﻷﻗﺮاصﻻ ﺗ ﺴﺘﻘﺮ ﰲ ا ﺴﺘﻮى اﻷوﺳـﻂ ﻟﻠﻘﺮص وﺑﺪﻻ ﻣﻦ ذﻟﻚ ﻳﻜﻮن اﻟﻐﺒـﺎر ﻋﺎﻟﻴـﺎً ﻓﻮق ا ﺴﺘﻮى اﻷوﺳﻂ ﻟﻠﻘﺮص ﻣﻤﺎ ﻳﺠﻌـﻞ اﻷﻗﺮاص ﺗﺒﺪو ﺳـﻤﻴﻜﺔ ﰲ اﻻﺗﺠـﺎه اﻟـﺮأﳼ وﻋﲆ اﻟﻨﻘﻴﺾ ﻣﻦ ذﻟﻚ ﰲ اﻷﻗـﺮاص اﻷﻛﺜـﺮ ﺗﻄﻮراً ﻳﺴﺘﻘﺮ اﻟﻐﺒﺎر ﰲ ا ﺴـﺘﻮى اﻷ وﺳـﻂ ﻣﻤــﺎ ﻳﺠﻌﻠﻬــﺎ ﺗﺒــ ﺪو أرق ﺑﻜﺜ ـ ، ﻳ ﻘــﻮل أوﻫﺎﳾ ": ﻟﻢ ﻧﺘﻮﻗﻊ رؤﻳﺔ ﻣﺜﻞ اﻻﺧﺘﻼﻓـﺎت اﻟﻮاﺿﺤﺔ ﺑ اﻷﻗﺮاص ﺣﻮل اﻟﻨﺠﻮم اﻷوﻟﻴﺔ واﻷﻗﺮاص اﻷﻛﺜﺮ ﺗﻄﻮراً " ، وﻳﻀـﻴﻒ ﺟـﻮن ﺗﻮﺑ أﺣﺪ ا ﺸﺎرﻛ اﻟﺮﺋﻴﺴﻴ ﰲ اﻟﱪﻧﺎﻣﺞ ﺑﺎ ﺮﺻــﺪ اﻟﻔﻠﻜــﻲ اﻟــﻮﻃﻨﻲ اﻟﺮادﻳــﻮي ) ﺑﺎﻟﻮﻻﻳـﺎت ا ﺘﺤــﺪة اﻻﻣﺮﻳﻜﻴـﺔ ": ( ﺗﺸـ ﻧﺘﺎﺋﺠﻨﺎ إﱃ أن اﻷﻗﺮاص ا ﺤﻴﻄـﺔ ﺑـﺎﻟﻨﺠﻮم ـــ اﻷوﻟﻴ ـﺔ ﻟﻴﺴ ـﺖ ﺟــﺎﻫﺰة ﺗﻤﺎﻣ ـﺎ ﻟﺘﻜ ـﻮﻳﻦ اﻟﻜﻮاﻛﺐ ." ﻧﺤﻦ ﻧﻌﺘﻘﺪ أن اﻟﺘﻜﻮﻳﻦ اﻟﻔﻌـﲇ ﻟﻠﻨﻈﺎم اﻟﻜـﻮﻛﺒﻲ ﻳﺘﻘـﺪم ﺑــﴪﻋﺔ ﺧـﻼل 100.000 ﺳﻨﺔ إﱃ 1.000.000 ﺳـﻨﺔ ﺑﻌـﺪ ﺑﺪء ﺗﻜﻮﻳﻦ اﻟﻨﺠﻮم ﻳﺸ. ﺟﻴﺲ ﻳﻮﺟﻨﺴـﻦ اﻟﺒﺎﺣﺚ اﻟﺮﺋﻴﴘ اﻵ ﺧﺮ ﰲ اﻟﱪﻧﺎﻣﺞ ﰲ ﻣﻌﻬﺪ ﻧﻴﻠﺰ ﺑﻮر ﺑﺠﺎﻣﻌـﺔ ﻛﻮﺑﻨﻬـﺎﺟﻦ ﺑﺎﻟـﺪﻧﻤﺎرك أﻳﻀﺎً إﱃ أﻫﻤﻴﺔ اﻟﺘﻌﺎون اﻟـﺪوﱄ ﰲ ﺗﺨﻄـﻴﻂ وﺗﻨﻔﻴﺬ ﻣﺜﻞ ﻫﺬا اﻟﱪﻧﺎﻣﺞ واﺳـﻊ اﻟﻨﻄـﺎق . ــــ ﻫﻨــﺎك 37 ﺑﺎﺣﺜــﺎً ﻣ ـﻦ 15 ﻣﻌﻬ ـﺪاً ﺑﺤﺜﻴ ـﺎً ﻳﺸﺎرﻛﻮن ﰲ ﻣﺠﻤﻮﻋﺔ اﻟﺒﺤﺚ اﻟﺪوﻟﻴﺔ اﻟﺘـﻲ روﺟﺖ ﻟﻬﺬا اﻟﺒﺤﺚ، ﺣﻮاﱄ ﻧﺼـﻔﻬﻢ ﻃـﻼب دراﺳﺎت ﻋﻠﻴـﺎ أو ﺑـﺎﺣﺜ ﺷـﺒﺎب ﺣﺼـﻠﻮا ﻣﺆﺧﺮاً ﻋﲆ درﺟـﺔ اﻟـﺪﻛﺘﻮراة . ﻳﺘـﻴﺢ ﻫـﺬا اﻟﺒﺤﺚ ﻟﻠﻌﺪﻳﺪ ﻣﻦ اﻟﺒﺎﺣﺜ اﻟﺸﺒﺎب ﻓﺮﺻـﺔ ا ﺸﺎرﻛﺔ ﰲ اﻟﱪاﻣﺞ اﻟﺪوﻟﻴﺔ وﻳﻤﻜﻦ اﻟﻘـﻮل أن ﻫﺬا اﻟﱪﻧﺎﻣﺞ ﻳﻠﻌﺐ دور اً رﺋﻴﺴﻴﺎً ﰲ ﺗﻌﺰﻳﺰ اﻟﺒﺤﺚ واﻟﺘﻌﺎون ﰲ ا ﺴﺘﻘﺒﻞ . ﺻﻮر اﻷﻗﺮاصﺣﻮال 19 ـﺎً ﻧ ﻤﺎً أوﻟ ـﺔ ﺗـﻢ ﻤـﺎ ﻓـﻲ ذﻟـﻚ أرﻌـﺔ أﻧﻈﻤـﺔ ﺛﻨﺎﺋ رﺻـﺪﻫﺎ ﺎﺳـﺘﺨﺪام ﻣﺮﺻـﺪ أﻟﻤـﺎ . ـــﺘﻢ ﻋـــﺮض اﻷﻗـــﺮاصﺣـــﻮل اﻟﻘـــﺮص اﻷﺳﺎﺳـــﻲواﻟﺜـــﺎﻧﻮي ﺸـــ ﻞ ﻣﺴــــﺘﻘﻞ ﺎﻟﻨﺴـــ ﺔ ﻟﻨﻈـــﺎم ﺛﻨـــﺎﺋﻲواﺣـــﺪ ) اﻟﺴﻄﺮ اﻟﺜﺎﻧﻲﻓﻲ أﻗﺼﻰ اﻟ ﻤ ( واﻟﺴﻄﺮ اﻟﺜﺎﻟﺚ ﻓﻲ أﻗﺼـﻰ اﻟ ﺴـﺎر .( ـﺐ ـﺘﻢ ﻋﺮﺿـﻬﺎ اﻷﻗـﺮاص ﺗﺴﻠﺴﻠﻬﺎ اﻟﺘﻄـﻮري ) ـﺔ اﻟ ﺴـﺮىﻫـﻮ اﻷﺻـﻐﺮﺑ ﻨﻤـﺎ ـﺔ اﻟﻌﻠﻮ ﻓـﻲ اﻟﺰاو اﻟـﺬ ـﺔ اﻟ ﻤـ ﻓـﻲ اﻟﺰاو اﻟـﺬ اﻟﺴـــﻔﻠ ﺔ ﻫـــﻮ اﻷﻗـــﺪم .( ـــﺔ ـــﻞ ﺧﺎﻓﺘـــﮫ ذاتﻓﺠـــﻮة ﺣﻠﻘ ﻈﻬـــﺮ اﻟﻘﺮﺻـــﺎن اﻷﻗـــﺪمﻫ ﺎ . ـــﺘﻢ ﻋـــﺮضﺷـــﺮﻂ ــﺎسﻗــﺪر ﻣﻘ ﻩ 20 ــﺔ وﺣــﺪة ﻓﻠﻜ )1 اﻷرضواﻟﺸــﻤﺲوﻫـــﻲ ــﺔ ﺗﺴــﺎوي اﻟﻤﺴــﺎﻓﺔ ﺑــ وﺣــﺪة ﻓﻠﻜ 150 ﻣﻠﻴﻮن ﻛ ﻠﻮﻣ ( ﻟ ﻞ ﺻﻮرة ﻗﺮص . ] ALMA (ESO/NAOJ/NRAO), N. Ohashi et al [