Free Astronomy Magazine March-April 2025 ARABIC VERSION

N 33 byNASA/ESA/CSA Ann Jenkins ChristinePulliam ASA’s James Webb Space Tel- escope just solved a conun- drumbyprovingacontrover- sial finding made with the agency’s Hubble Space Telescope more than 20 years ago. In 2003, Hubble provided evidence of a massive planet around a very old star, almost as old as the uni- verse.Suchstarspossessonlysmall amounts of heavier elements that are the building blocks of planets. This implied that some planet for- mation happened when our uni- verse was very young, and those planets had time to form and grow big inside their primordial disks, even bigger than Jupiter. But how? This was puzzling. To answer this question, researchers usedWebbtostudystarsinanearby galaxy that, much like the early uni- verse, lacks large amounts of heavy elements. They found that not only do some stars there have planet- forming disks, but that those disks are longer-lived than those seen around young stars in our Milky Way galaxy. “With Webb, we have a re- ally strong confirmation of what we saw with Hubble, and we must re- think how we model planet forma- tion and early evolution in theyoung universe,” said study leader GuidoDeMarchioftheEuropean SpaceResearch and Technol- ogyCentrein Noordwijk, Netherlands.Int heearly universe,stars formed from mostlyhydro- genandhe- lium,andvery fewheavierelementssuchascarbon and iron, which came later through supernova explosions. “Current models predict that withso few heavier elements, the disks around stars have a short lifetime, so short in fact that planets cannot grow big,” said the Webb study’sco- investigator Elena Sabbi, chief scientist for Gemini Observatory at the National Science Foundation’s NOIRLab in Tucson. “But Hubble did see those planets, so what if the models were not correct and disks could live longer?” To test this idea, scientists trained WebbontheSmallMagellanic Cloud,adwarfgalaxythatisoneof the Milky Way’s nearest neighbors. Inparticular,theyexaminedthe massive,star-formingclusterNGC 346,whichalsohasarelativelackof heavierelements.Theclusterserved asanearbyproxyforstudyingstellar environmentswithsimilarcondi- tionsintheearly,distantuniverse. HubbleobservationsofNGC346 from the mid 2000 revealed many starsabout20to30millionyearsold thatseemedtostillhaveplanet- formingdisksaroundthem.This went against the conventional be- lief that such disks would dissipate after 2 or 3 million years. “The Hubble findings were contro- versial, going against not only em- pirical evidence in our galaxy but also against the current models,” said De Marchi. “This was intrigu- ing, but without a way to obtain spectra of those stars, we could not really establish whether we were witnessing genuine accretion andthe presence of disks, or just some artificial effects.” Now, thanks to Webb’s sensitivity and resolution, scientists have the first-ever spectra of forming, Sun- like stars and their immediate envi- ronments in a nearby galaxy. “Weseethatthesestarsareindeed surroundedbydisksandarestill in MARCH-APRIL2025 : ﻘﻠﻢ آن ﺟ ﻨﻜ و ﺑﻮﻟ ﺎم ﻛﺮﺴﺘ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ اﻟـــﺘﻘﻂ ــــﺐ اﻟﻔﻀــــﺎﺋﻲ ﺗﻠﺴــــ ﻮبﺟــــ ﻤﺲو اﻟ ﻫــــﺬﻩ ﺼــــﻮرة ﻟـــــ NGC346 وﻫــــﻮ ﻋﻨﻘــﻮد ﻧ ﻤــﻲﺿــ ﻢ ﻘــﻊ ﻓــﻲﺳـــﺤﺎ ﺔ ﻣــﺎﺟﻼن اﻟﺼــﻐ ة، وﻫــﻲﻣﺠــﺮة ﺔ ﻗﺰﻣـــ ﺗﻌﺪ ﻣﻦ أﻗﺮ ﺟ ان در اﻟﺘ ﺎﻧﺔ ـ وﻧﻈﺮاً ﻟ ﻣﻦ اﻟﻌﻨﺎﺻﺮ ﺨﻠﻮﻫﺎ اﻟﻨﺴ اﻷﺛﻘﻞ ﻣﻦ واﻟﻬ ﻠﻴـــﻮم ـــﺪروﺟ اﻟﻬ ﻓـــﺈن ﻋﻨﻘـــﻮد NGC346 ـــﺔ ﻌﻤـــﻞ ﻤﺜﺎ ﻧﻤـــﻮذج ﻗﺮ ــــﺐ ـــﻮن اﻟﻤ ﻜـــﺮ ـــﺔ ذات اﻟﻈـــﺮوف اﻟﻤﻤﺎﺛﻠــﺔ ﻓـــﻲ اﻟ ﻟﺪراﺳــﺔ اﻟﺒﻴﺌـــﺎت اﻟﻨ ﻤ ـــﺪ و اﻟ ﻌ . ـــﺔ ﻋﻠــﻰ اﻟﺼــﻮرة إﻟـــﻰﻣﻮاﻗــﻊ اﻟﻨﺠـــﻮم ﺗﺸــ ﻋﺸــﺮ دواﺋـــﺮﺻــﻔﺮاء ﺻــﻐ ة ﻣ اﻛ اﻟﻌﺸﺮة ﺗﻢ ﻣﺴﺤﻬﺎ ﻓﻲﻫﺬﻩ اﻟﺪراﺳﺔ اﻟ . [NASA,ESA,CSA,STScI,OliviaC.Jones(UKATC),Guido De Marchi (ESTEC), Margaret Meixner (USRA)] ﻧﺠﺢ ﺗﻠﺴﻜﻮبﺟﻴﻤﺲ وﻳﺐ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ ﰲ ﺣﻞ ﻣﻌﻀﻠﺔ ﻋﻠﻤﻴﺔ ﻣﻦ ﺧﻼل إﺛﺒﺎت اﻛﺘﺸﺎف ﻣﺜ ﻟﻠﺠﺪل ﺗﻢ اﻟﺘﻮﺻﻞ إﻟﻴﻪ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟ ﺘـﺎﺑﻊ ﻟﻠﻮﻛﺎﻟﺔ ﻣﻨﺬ أﻛﺜﺮ ﻣﻦ 20 . ﺎً ﻋﺎﻣ ﻓﻔﻲ ﻋﺎم 2003 ﻗﺪم ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ دﻟـﻴﻼً ﻋﲆ وﺟﻮ د ﻛﻮﻛﺐ ﺿﺨﻢ ﻳـﺪور ﺣـﻮل ﻧﺠـﻢ ﻗﺪﻳﻢ ﺟﺪ اً ﻳﻜـﺎد ﻳﻜـﻮن ﻋﻤـﺮه ﻣﺜـﻞ ﻋﻤـﺮ اﻟﻜﻮن . ﺗﻤﺘﻠﻚ ﻣﺜـﻞ ﻫـﺬه اﻟﻨﺠـﻮم ﻛﻤﻴـﺎت ﺻﻐ ة ﻓﻘﻂ ﻣﻦ اﻟﻌﻨـﺎﴏ اﻟﺜﻘﻴﻠـﺔ اﻟﺘـ ﻲ ﺗﺸﻜﻞ اﻟﻠﺒﻨﺎت اﻷﺳﺎﺳـﻴﺔ ﻟﻠﻜﻮاﻛـﺐ وﻫـﺬا ﻳﻌﻨـﻲ أن ﺑﻌـﺾ ﺗﻜـﻮﻳﻦ اﻟﻜﻮاﻛـﺐ ﺣـﺪث ﻋﻨﺪﻣﺎ ﻛﺎن ﻛﻮﻧﻨﺎ ﺻﻐ اً ﺟـﺪاً وﻛـﺎن ﻟـﺪى ﻫﺬه اﻟﻜﻮاﻛﺐ اﻟﻮﻗﺖ اﻟﻜﺎﰲ ﻟﻠﺘﺸﻜﻞ واﻟﻨﻤﻮ ﺑﺸﻜﻞ ﻛﺒ داﺧﻞ أﻗﺮاﺻﻬﺎ اﻟﺒﺪاﺋﻴـﺔ ﻲ واﻟﺘـ ﻛﺎﻧﺖ أﻛﱪ ﺣﺘﻰ ﻣﻦ ﻛﻮﻛﺐ ا ﺸﱰي وﻟﻜـﻦ ﻛﻴﻒ؟ ﻛﺎن ﻫﺬا ﻣﺤ .اً ﻟﻺﺟﺎﺑﺔ ﻋﲆ ﻫﺬا اﻟﺴﺆال اﺳﺘﺨﺪم اﻟﺒﺎﺣﺜﻮن ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ ﻟﺪراﺳـﺔ اﻟﻨﺠـﻮم ﰲ ﺠﺮة ﻣ ﻗﺮﻳﺒﺔ ﺗﻔﺘﻘﺮ، ﻣﺜﻞ اﻟﻜﻮن ا ﺒﻜـﺮ، إﱃ ﻛﻤﻴﺎت ﻛﺒ ة ﻣـﻦ اﻟﻌﻨـﺎﴏ اﻟﺜﻘﻴﻠـﺔ وﻗـﺪ وﺟﺪ وا أن ﺑﻌﺾ اﻟﻨﺠﻮم ﻫﻨﺎك ﻟـ ﻴﺲ ﻓﻘـﻂ ﻟﺪﻳﻬﺎ أﻗﺮاص ﺗﺸﻜﻞ اﻟﻜﻮاﻛﺐ ﺑـﻞ إن ﻫـﺬه اﻷﻗﺮاص أﻃﻮل ﻋﻤﺮ اُ ﻣﻦ ﺗﻠـﻚ اﻟﺘـﻲ ﻧﺮاﻫـﺎ ﺣﻮل اﻟﻨﺠﻮم اﻟﺸﺎﺑﺔ ﰲ ﻣﺠﺮﺗﻨﺎ درب اﻟﺘﺒﺎﻧﺔ . ﻗﺎل ﻗﺎﺋﺪ اﻟﺪراﺳﺔ ﺟﻴﺪو دي ﻣﺎرﺷـﻴﻮ ﻣـﻦ ا ﺮﻛ ــﺰ اﻷوروﺑـــﻲ ﻷﺑﺤ ــﺎث اﻟﻔﻀـــﺎء واﻟﺘﻜﻨﻮﻟﻮﺟﻴـــﺎ ﰲ ﻧﻮردﻓﻴـــﻚ ﺑﻬﻮﻟﻨـــﺪا : " ﺑﺘﻠﺴﻜﻮب وﻳﺐ ﻟﺪﻳﻨﺎ ﺗﺄﻛﻴﺪ ﻗﻮي ﺣﻘًـﺎ ـﺎ رأﻳﻨﺎه ﻣﻊ ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ وﻳﺠـﺐ أن ﻧﻌﻴـﺪ اﻟﺘﻔﻜــــــــــــــــــــــــــــ ﰲ ﻛﻴﻔﻴ ﺔ ﻧﻤﺬﺟـــﺔ ﺗﻜــﻮﻳﻦ اﻟﻜﻮاﻛــﺐ واﻟﺘﻄـﻮر ا ﺒﻜـﺮ ﰲ اﻟﻜﻮن اﻟﺒﺪاﺋﻲ ." ﰲ اﻟﻜــﻮن ا ﺒﻜــﺮ ﺗﺸﻜﻠﺖ اﻟﻨﺠﻮم ﻣﻦ اﻟﻬﻴـــــــﺪروﺟ واﻟﻬﻴﻠﻴﻮم ﰲ اﻟﻐﺎﻟﺐ وﻗﻠﻴــﻞ ﺟــ ﺪ ا ﻣــﻦ اﻟﻌﻨ ـﺎﴏ اﻟﺜﻘﻴﻠــﺔ اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠـﺔ ﻣﺜـﻞ اﻟﻜﺮﺑـﻮن واﻟﺤﺪﻳـﺪ واﻟﺘـﻲ ﺟـﺎءت ﰲ وﻗـﺖ ﻻﺣـﻖ ﻣـﻦ ﺧـﻼل اﻧﻔﺠﺎرات ا ﺴﺘﻌﺮات اﻟﻌﻈﻤﻰ . ﻗﺎﻟﺖ اﻟﺒﺎﺣﺜﺔ ا ﺸﺎر ﻛﺔ ﰲ دراﺳﺔ ﺗﻠﺴـﻜﻮب وﻳﺐ إﻳﻠﻴﻨﺎ ﺳﺎﺑﻲ ﻛﺒ ة اﻟﻌﻠﻤـﺎء ﰲ ﻣﺮﺻـﺪ ﺟﻴﻤﻴﻨﻲ ﰲ ﻣﺨﺘﱪ ﻧﻮﻳﺮﻻب ": ﺗﺘﻨﺒﺄ اﻟﻨﻤـﺎذج ا ﻟﺤﺎﻟﻴﺔ ﺑﺄﻧﻪ ﻣﻊ وﺟﻮد ﻋﺪد ﻗﻠﻴﻞ ﺟـﺪ اً ﻣـﻦ اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ ﻓـﺈن اﻷﻗـﺮ اص ا ﺤﻴﻄـﺔ ﺑﺎﻟﻨﺠﻮم ﻟﻬﺎ ﻋﻤـﺮ ﻗﺼـ ﺟـﺪ ا ﰲ اﻟﻮاﻗـﻊ ﻟﺪرﺟﺔ أن اﻟﻜﻮاﻛﺐ ﻻ ﻳﻤﻜﻦ أن ﺗﻨﻤﻮ ﺑﺸﻜﻞ ﻛﺒ ﺗﻠﺴ ﻟﻜﻦ ﻜﻮب ﻫﺎﺑﻞ رأى ﺗﻠﻚ اﻟﻜﻮاﻛﺐ ﻓﻤﺎذا ﻟـﻮ ﻛﺎﻧـﺖ اﻟﻨﻤـﺎذج ﻏـ ﺻـﺤﻴﺤﺔ وﻳﻤﻜﻦ ﻟﻸﻗﺮاص أن ﺗﻌﻴﺶ ﻟﻔﱰة أﻃـﻮل؟ " ﻻﺧﺘﺒﺎر ﻫﺬه اﻟﻔﻜﺮة درب اﻟﻌﻠﻤﺎء ﺗﻠﺴﻜﻮب وﻳﺐ ﻋﲆ ﺳﺤﺎﺑﺔ ﻣﺎﺟﻼن اﻟﺼـﻐ ﺮى وﻫـﻲ ﻣﺠﺮة ﻗﺰﻣﺔ ﻣﻦ أﻗﺮب ﺟ ان درب اﻟﺘﺒﺎﻧـﺔ و ﻗﺎﻣﻮا ﺑﻔﺤﺺ اﻟﻌﻨﻘﻮد اﻟﻀﺨﻢ NGC 346 اﻟﺬي ﻳﺸﻜﻞ اﻟﻨﺠﻮم ﻳﻔ و ﺘﻘﺮ أﻳﻀًﺎ ﻧﺴﺒﻴ إﱃ ﺎً اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ . ﻛﺎن اﻟﻌﻨﻘﻮد ﺑﻤﺜﺎﺑﺔ ﻧﻤﻮذج ﻗﺮﻳﺐ ﻟﺪراﺳـﺔ اﻟﺒﻴﺌﺎت اﻟﻨﺠﻤﻴﺔ ذات اﻟﻈـﺮوف ا ﻤﺎﺛﻠـﺔ ﰲ اﻟﻜﻮن ا ﺒﻜﺮ اﻟﺒﻌﻴـﺪ وﻗـﺪ ﻛﺸـﻔﺖ أرﺻـﺎد ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ ﻋـﻦ NGC346 ﰲ ﻣﻨﺘﺼـﻒ ﻋﺎم 2000 ﻋﻦ اﻟﻌﺪﻳﺪ ﻣﻦ اﻟﻨﺠﻮم اﻟﺘﻲ ﻳﺒﻠﻎ ﻋﻤﺮﻫﺎ ﻣﻦ 20 إﱃ 30 ﻣﻠﻴـﻮن ﺳـﻨﺔ واﻟﺘـﻲ ﻳ ﺒﺪو أﻧﻬﺎ ﻻ ﺗﺰال ﺗﺤﺘﻮي ﻋﲆ أﻗ ﺮاص ﺗﺸﻜﻞ اﻟﻜﻮاﻛﺐ ﺣﻮﻟﻬﺎ وﻫﺬا ﻳﺘﻌﺎرض ﻣﻊ اﻻﻋﺘﻘﺎد اﻟﺘﻘﻠﻴﺪي ﺑﺄن ﻣﺜـﻞ ﻫـﺬه اﻷﻗـﺮاصﺳـﻮف ﺗﺘﺒﺪد ﺑﻌﺪ 2 أو 3 ﻣﻼﻳ ﺳﻨﺔ . ﻗﺎل دي ﻣﺎرﳾ " : ﻧﺘـﺎﺋﺞ ﺗﻠﺴـﻜﻮب ﻫﺎﺑـﻞ ﻣﺜ ة ﻟﻠﺠﺪل ﺣﻴﺚ ﺗﺘﻌﺎرض ﻟﻴﺲ ﻓﻘﻂ ﻣﻊ اﻷدﻟﺔ اﻟﺘﺠﺮﻳﺒﻴﺔ ﰲ ﻣﺠﺮﺗﻨـﺎ وﻣـﻊ اﻟﻨﻤـﺎذج اﻟﺤﺎﻟﻴﺔ ﻫﺘﻤـﺎم ﻺ ﻟ ﻫﺬا ﻣﺜ و وﻟﻜـﻦ ﺑـﺪون ﻃﺮ ﻳﻘﺔ ﻟﻠﺤﺼﻮل ﻋﲆ أﻃﻴﺎف ﺗﻠﻚ اﻟﻨﺠﻮم ﻟﻢ ﻧﺘﻤﻜﻦ ﻣﻦ ﺗﺤﺪﻳﺪ ﻣﺎ إذا ﻛﻨﺎ ﻧﺸﻬﺪ ﺗﺮاﻛﻤـﺎَ ﺎَ ﺣﻘﻴﻘﻴ ووﺟﻮد أﻗـﺮاص أو ﻣﺠـﺮد ﺑ ﻌـﺾ اﻟﺘﺄﺛ ات اﻻﺻﻄﻨﺎﻋﻴﺔ ". اﻵن ﺑﻔﻀﻞ ﺣﺴﺎﺳﻴﺔ ﺗﻠﺴﻜﻮب وﻳﺐ ودﻗﺘﻪ أﺻﺒﺢ ﻟﺪى اﻟﻌﻠﻤﺎء أول أﻃﻴﺎف ﻋﲆ اﻹﻃﻼق ﻟﻨﺠﻮم ﺗ ﺘﺸﻜﻞ ﺷﺒﻴﻬﺔ ﺑﺎﻟﺸـﻤﺲ وﺑﻴﺌﺎﺗﻬـﺎ ا ﺒﺎﴍة ﰲ ﻣﺠﺮة . ﻗﺮﻳﺒﺔ ﻧـﺮى أن ﻫـﺬه اﻟﻨﺠـﻮم ﻣﺤﺎﻃـﺔ ﺑﺎﻟﻔﻌ ـﻞ 33