Free Astronomy Magazine July-August 2026 ARABIC VERSION

ASTROPUBLISHING 13 called accretion. Dust gloms to- gether into pebbles, which collide andgrowlargerandlarger,forming protoplanetsandeventuallyplanets. The largest then collect gas to be- come giants like Jupiter. Since it takes more time for gas giants to form, and the disk of planet-form- ing material eventually evaporates and disappears, planetary systems endupwithmanymoresmallplan- etsthanlargeplanets.Incontrast, starsformwhenavastcloudofgas fragmentsandeachpiececollapses under its own gravity, growing smaller and denser. A similar frag- mentation process could theoreti- cally occur within protoplanetary disksaswell.Thatcouldexplainwhy someverymassiveobjectsarefound billionsofmilesfromtheirhoststars, inregionswheretheprotoplanetary disk should have been too tenuous for accretion to occur. 29 Cygni b sits on the dividing line between what can be explained by these two different mechanisms. It weighs 15 times Jupiter and orbitsits star at an average distance of 1.5 billion miles (2.4 billion kilometers), about the same as Uranus in oursolarsystem.Theresearchteamtar- geted it because it could potentially result from either process. “In computer models, it’s very easy forfragmentationinadisktorun JULY-AUGUST2026 واﻟﻐﺒﺎر ا ﺤﻴﻄﺔ ﺑﺎﻟﻨﺠﻮم ﻋﱪ ﻋﻤﻠﻴﺔ ﺗُﺴـﻤﻰ اﻟﱰاﻛﻢ ﺣﻴﺚ ﺗﻠﺘﺼﻖ ﺟﺰﻳﺌﺎت اﻟﻐﺒﺎر ﺑﺒﻌﻀﻬﺎ ﻟﺘﻜﻮّن ﺣ ﻐ ة ﴡ ﺻ ـ ﺛـﻢ ﺗﺘﺼـﺎدم وﺗﻨﻤـﻮ ﺗﺪرﻳﺠﻴﺎً ﻟﺘﺸﻜّ ﻞ ﻛﻮاﻛﺐ أوﻟﻴـﺔ، ﺛـﻢ ﻛﻮاﻛـﺐ ﻣﻜﺘﻤﻠﺔ وﺗﻘﻮم اﻟﻜﻮاﻛﺐ اﻷﻛﱪ ﻻﺣﻘﺎً ﺑﺠـﺬب ﻐﺎ اﻟ ز ﻟﺘﺘﺤﻮل إﱃ ﻋﻤﺎﻟﻘﺔ ﻣﺜﻞ ا ﺸﱰي وﺑﻤـﺎ أن ﺗﻜﻮّن اﻟﻌ ﻤﺎﻟﻘﺔ اﻟﻐﺎزﻳـﺔ ﻳﺴـﺘﻐﺮق وﻗﺘـﺎً أﻃﻮل ﻓﺈن ﻗـﺮص ا ـﺎدة ا ﻟﻜﻮﻛﺒﻴـﺔ ﻳﺨﺘﻔـﻲ ﺗﺪرﻳﺠﻴﺎً ﻣﻊ اﻟـﺰﻣﻦ ﻟـﺬﻟﻚ ﺗﻨﺘﻬـﻲ اﻷﻧﻈﻤـﺔ اﻟﻜﻮﻛﺒﻴـﺔ ﻋـﺎدة ﺑﻌـﺪد أﻛـﱪ ﻣـﻦ اﻟﻜﻮاﻛـﺐ ـــــــــــــــــــــــــــــــــــــ اﻟﺼـﻐ ة ﻣﻘﺎ رﻧــﺔ ﺑﺎﻟﻜﻮاﻛـﺐ اﻟﻀـﺨﻤﺔ ﰲ . ا ﻘﺎﺑﻞ ﺗﺘﺸﻜﻞ اﻟﻨﺠﻮم ﻋﻨﺪﻣﺎ ﺗﻨﻬﺎر ﺳـﺤﺎﺑﺔ ﺿ ﺨﻤﺔ ﻣـﻦ اﻟﻐـﺎز ﺗﺤـﺖ ﺗـﺄﺛ ﺟﺎذﺑﻴﺘﻬـﺎ ﻓﺘﺘﺠﺰأ إﱃ أﺟﺰاء أﺻﻐﺮ و أﻛﺜﺮ ﻛﺜﺎﻓـﺔ . وﻣـﻦ اﻟﻨﺎﺣﻴﺔ اﻟﻨﻈﺮﻳـﺔ ﻳﻤﻜـﻦ أن ﺗﺤـﺪث ﻋﻤﻠﻴـﺔ ﺗﺠﺰؤ ﻣﺸـﺎﺑﻬﺔ داﺧـﻞ اﻷﻗـﺮاص اﻟﻜﻮﻛﺒﻴـﺔ اﻷ وﻟﻴﺔ أﻳﻀﺎً ﻣﻤﺎ ﻗﺪ ﻳﻔـ ـ ﴪ وﺟـﻮد أﺟﺴـﺎم ﺟﺪ ﺿﺨﻤﺔ اً ﻋﲆ ﻣﺴﺎﻓﺎت ﺑﻌﻴﺪة ﻣﻦ ﻧﺠﻮﻣﻬﺎ ﰲ ﻣﻨﺎﻃﻖ ﻳ ﻔﱰض أن اﻟﻘﺮص ﻓﻴﻬﺎ رﻗﻴﻖ ﺟﺪاً ﺑﺤﻴﺚ ﻻ ﻳﺴﻤﺢ ﺑﺤﺪوث اﻟـﱰاﻛﻢ اﻟﺘﻘﻠﻴـﺪي . ـــــــــــــــــــــــــــــــــــــ ﻳﻘﻊ اﻟﺠﺮم 29 Cygni b ﻋﲆ اﻟﺤﺪ اﻟﻔﺎﺻـﻞ ﺑ ﻫﺎﺗ اﻵﻟﻴﺘ ا ﺤﺘﻤﻠﺘ . ﻓﻜﺘﻠﺘـﻪ ﺗﺒﻠـﻎ 15 ﻣﺮة ﻛﺘﻠﺔ ا ﺸﱰي وﻳﺪور ﺣﻮل ﻧﺠﻤﻪ ﻋﲆ ﻣﺴﺎﻓﺔ ﻣﺘﻮﺳﻄﺔ ﺗﺒﻠﻎ 1.5 ﻣﻠﻴﺎر ﻣﻴـﻞ )2.4 ﻣﻠﻴ ـﺎر ﻛﻴﻠ ـﻮﻣﱰ ( أي ﻣ ـﺎ ﻳﻘ ـﺎرب ﻣﺴ ـﺎﻓﺔ أوراﻧﻮس ﻋﻦ اﻟﺸﻤﺲ ﰲ ﻧﻈﺎ . ﻤﴘـ ﻣﻨﺎ اﻟﺸـ اﺧﺘﺎر ﻓﺮﻳﻖ اﻟﺒﺤﺚ ﻫﺬا اﻟﺠ م ﻷ ﺮ ﻧﻪ ﻗﺪ ﻳﻜـﻮن ﻧﺎﺗﺠﺎً ﻋﻦ أي ﻣﻦ اﻟﻄﺮﻳﻘﺘ . ﻗﺎل ا ﺆﻟﻒ اﻟﺮﺋﻴﴘ وﻳﻠﻴﺎم ﺑﺎ ﺮ ﻣﻦ ﺟﺎﻣﻌـﺔ ﺟﻮﻧﺰ ﻫﻮﺑﻜﻨﺰ وﻣﻌﻬﺪ ﻋﻠﻮم ﺗﻠﺴﻜﻮب اﻟﻔﻀﺎء ـــــــــــــــــــــــــــــــــــــ - ﻳﻮﻟﻴﻮ ﺃﻏﺴﻄﺲ 2 0 2 6 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 13