Free Astronomy Magazine July-August 2025 ARABIC VERSION

T The atmospheric makeup of small, hot, gassy sub-Neptune TOI-421 b byNASA/ESA/CSA ClaireBlome5Christine Pulliam houghtheydon’torbitaround ourSun,sub-Neptunesarethe mostcommontypeofexo- planet, or planet outside our solar system,thathavebeenobservedin ourgalaxy.Thesesmall,gassyplan- ets are shrouded in mystery…and often,alotofhaze.Now,byobserv- ing exoplanet TOI-421 b, NASA’s JamesWebbSpaceTelescopeishelp- ing scientists understand sub-Nep- tunesinawaythatwasnotpossible prior to the telescope’s launch. “Ihadbeenwaitingmyentirecareer forWebbsothatwecouldmeaning- fullycharacterizetheatmospheres ofthesesmallerplanets,” saidprin- cipal investigator Eliza Kempton of theUniversityofMaryland,College Park. “By studying their atmos- pheres,we’regettingabetterun- derstanding of how sub-Neptunes formed and evolved, and part of that is understanding why they don’t exist in our solar system.” Theexistenceofsub-Neptuneswas unexpected before they were dis- covered by NASA’s retired Kepler spacetelescopeinthelastdecade. Now,astronomersaretryingtoun- derstandwheretheseplanetscame fromandwhyaretheysocommon. BeforeWebb,scientistshadverylit- tleinformationonthem.Whilesub- Neptunes are a few times larger than Earth, they are still much smaller than gas-giant planets and typically cooler than hot Jupiters, making them much more challeng- ing to observe than their gas-giant counterparts. AkeyfindingpriortoWebbwas thatmostsub-Neptuneatmospheres hadflatorfeaturelesstransmission spectra.Thismeansthatwhenscien- tists observed the spectrum of the planetasitpassedinfrontofitshost star,insteadofseeingspectralfea- tures–thechemicalfingerprints that would reveal the composition oftheatmosphere–theysawonlya flat-linespectrum.Astronomerscon- cludedfromallofthoseflat-line spectrathatatleastcertainsub-Nep- tuneswereprobablyveryhighlyob- scured by either clouds or hazes. “Why did we observe this planet, TOI-421b?It’sbecausewethought thatmaybeitwouldn’thavehazes,” said Kempton. “And the reason is thatthereweresomepreviousdata thatimpliedthatmaybeplanets overacertaintemperaturerange JULY-AUGUST2025 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 30 اﻟﺘ ﻮﻳﻦ ـاﻟ ﺠﻮيﻟﻠ ﻮﻛﺐ اﻟﻨ ﻤﻲاﻟﺼﻐ واﻟﺴﺎﺧﻦ TOI-421 b : ﻘﻠﻢ ﺑﻮﻟ ﺎم ﻠ ﻠﻮم ﻛﺮﺴﺘ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ ﺗﻌﺘـ اﻟﻜﻮاﻛﺐ ﺗﺤﺖ ﻧﺒﺘﻮﻧ ﻴـﺔ ﻫـﻲ اﻟﻨـﻮع اﻷﻛﺜـﺮ ﺷـﻴﻮﻋﺎ ﻣـﻦ اﻟﻜﻮاﻛـﺐ اﻟ ﻨﺠﻤﻴـﺔ أو اﻟﻜﻮاﻛـﺐ ﺧـﺎرج ﻧﻈﺎﻣﻨـﺎ اﻟﺸﻤـ ﴘـ اﻟﺘـﻲ رﺻﺪت ﰲ ﻣﺠﺮﺗﻨﺎ . ﻫﺬه اﻟﻜﻮاﻛـﺐ اﻟﺼـﻐ ة اﻟﻐﺎزﻳﺔ ﻣﺤﺎﻃﺔ ﺑﺎﻟﻐﻤﻮض وﻏﺎﻟﺒ ﺎً ﻣﺎ ﺗﻜـﻮ ن ﻣﺤﺎﻃﺔ ﺑﺎﻟﻜﺜ ﻣﻦ اﻟﻀﺒﺎب اﻵن . ﻣﻦ ﺧـﻼ ل ﻣﺮاﻗﺒﺔ اﻟﻜﻮﻛﺐ اﻟ ﻨﺠﻤﻲ TOI-421 b ﻳﺴﺎﻋﺪ ﺗﻠﺴـﻜﻮب ﺟـﻴﻤﺲ وﻳـﺐ اﻟﻔﻀـﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ اﻟﻌﻠﻤﺎء ﻋﲆ ﻓﻬﻢ اﻟﻜﻮاﻛﺐ ﺗﺤﺖ ﻧﺒﺘﻮن ﺑﻄﺮﻳﻘﺔ ﻟﻢ ﺗﻜﻦ ﻣﻤﻜﻨﺔ ﻗﺒـﻞ إﻃـﻼق اﻟﺘﻠﺴﻜﻮب . ﻗﺎﻟـﺖ اﻟﺒﺎﺣﺜـﺔ اﻟﺮﺋﻴﺴـﻴﺔ إﻟﻴـﺰا ﻛﻴﻤﺒﺘﻮن ﻣﻦ ﺟﺎﻣﻌﺔ ﻣﺎرﻳﻼﻧﺪ ﻛﻮﻟﻴﺪج ﺑـﺎرك : " ﻛﻨﺖ أﻧﺘﻈﺮ ﺗﻠﺴﻜﻮب وﻳﺐ ﻃـﻮال ﻣﺴـ ﺗﻲ ا ﻬﻨﻴﺔ ﺣﺘﻰ ﻧﺘﻤﻜﻦ ﻣﻦ ﺗﻮﺻﻴﻒ أﻏ ﻠﻔﺔ ﻫـﺬه اﻟﻜﻮاﻛﺐ اﻟﺼﻐ ة ﺑﺪﻗﺔ . وأﺿﺎﻓﺖ " : ﺑﺪراﺳﺔ أﻏﻠﻔﺘﻬﺎ اﻟﺠﻮﻳﺔ ﻧﺼﻞ إﱃ ﻓﻬﻢ أﻓﻀﻞ ﻟﻜﻴﻔﻴﺔ ﺗﺸﻜﻞ وﺗﻄـﻮر اﻟﻜﻮاﻛـﺐ ﺗﺤﺖ ﻴﺔ ﻧﺒﺘﻮﻧ وﺟﺰء ﻣﻦ ذﻟﻚ ﻫﻮ ﻓﻬـﻢ ﺳـﺒﺐ ـــــــــــــــــــــــــــــــ ﻋـــﺪم ﻋﺪم وﺟﻮدﻫﺎ ﰲ ﻧﻈﺎﻣﻨﺎ اﻟ . ﺸﻤﴘـ ﻟﻘﺪ ﻛﺎن وﺟﻮد اﻟﻜﻮاﻛﺐ ﺗﺤﺖ ﻧﺒﺘﻮﻧ أﻣﺮ ﻴﺔ ا ﻏ ﻣﺘﻮﻗﻊ ﻗﺒـﻞ اﻛﺘﺸـﺎﻓﻬﺎ ﺑﻮاﺳـﻄﺔ ﺗﻠﺴـﻜﻮب ﻛﻴﺒﻠـﺮ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟ ﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ وا ﻨﺘﻬﻴﺔ ﻣﻬﻤﺘﻪ ﰲ اﻟﻌﻘﺪ ا ﺎﴈ اﻵن . ﻳﺤﺎول ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻓﻬﻢ ﻣﻦ أ ﻳﻦ ﺟﺎءت ﻫﺬه اﻟﻜﻮاﻛﺐ وﺳﺒﺐ ﺷﻴﻮﻋﻬﺎ ﻗﺒﻞ ﺗﻠﺴﻜﻮب وﻳﺐ ﻛﺎﻧﺖ ا ﻌﻠﻮﻣﺎت ا ﺘـﻮﻓﺮ ة ﻋﻦ اﻟﻜﻮاﻛﺐ ﺗ ﻴﺔ ﺤﺖ ﻧﺒﺘﻮﻧ ﻗﻠﻴﻠﺔ ﺟﺪ اً ﻓﺒﻴﻨﻤـﺎ ﺗ ﻌﺘﱪ اﻟﻜﻮاﻛﺐ ﺗﺤـ ﻴـﺔ ﺖ ﻧﺒﺘﻮﻧ أﻛـﱪ ﺑﺒﻀـﻊ ﻣﺮات ﻣﻦ اﻷرض إﻻ أﻧﻬﺎ ﻻ ﺗﺰال أﺻﻐﺮ ﺑﻜ ﺜ ﻣﻦ اﻟﻜﻮاﻛﺐ اﻟﻐﺎزﻳـﺔ اﻟﻌﻤﻼﻗـﺔ وﻋـﺎدة ﻣـﺎ ﺗﻜﻮ ن أﺑﺮد ﻣﻦ اﻟ ﻜﻮاﻛﺐ ا ﺸـﱰ ﻳﺔ اﻟﺴـﺎﺧﻨﺔ ﻣﻤﺎ ﻳﺠﻌﻞ رﺻﺪﻫﺎ أﻛﺜﺮ ﺻﻌﻮ ﺑﺔ ﻣﻦ ﻧﻈ اﺗﻬﺎ اﻟﻐﺎزﻳﺔ اﻟﻌﻤﻼﻗﺔ وﻣﻦ اﻟﻨﺘﺎﺋﺞ اﻟﺮﺋﻴﺴﻴ ﺔ ﻗﺒـﻞ ﺗﻠﺴﻜﻮب وﻳـﺐ أن ﻣﻌﻈـﻢ اﻷﻏﻠﻔـﺔ اﻟﺠﻮﻳـﺔ ﻟﻠﻜﻮاﻛﺐ ﺗﺤﺖ ﻧﺒﺘﻮﻧ ﻴـﺔ ﻛﺎﻧـﺖ ذات أﻃﻴـﺎف ﻧﻔﺎذﻳﺔ ﻣﺴﻄﺤﺔ ﺧﺎﻟﻴـﺔ ﻣـﻦ ا ﻼﻣـﺢ وﻫـﺬا ﻳﻌﻨﻲ أﻧﻪ ﻋﻨﺪﻣﺎ رﺻﺪ اﻟﻌﻠﻤﺎء ﻃﻴﻒ اﻟﻜﻮﻛـﺐ ـــــــــــــــــــــــــــــــــــــ أﺛﻨﺎء ﻣﺮوره أﻣﺎم ﻧﺠﻤﻪ ﺑﺪﻻً ﻣﻦ رؤﻳﺔ ا ﻼﻣﺢ اﻟﻄﻴﻔﻴﺔ وﻫـﻲ اﻟﺒﺼـﻤﺎت اﻟﻜﻴﻤﻴﺎﺋﻴـﺔ اﻟﺘـﻲ ﺗﻜﺸﻒ ﻋﻦ ﺗﺮﻛﻴﺐ اﻟﻐﻼف اﻟ ﺠـﻮي ﻟـﻢ ﻳـﺮوا ﺳﻮى ﻃﻴﻒ ﺧﻄﻲ ﻣﺴﻄﺢ . اﺳـﺘﻨﺘﺞ ﻋﻠﻤـﺎء اﻟﻔﻠﻚ ﻣﻦ ﺟﻤﻴﻊ أﻃﻴﺎف اﻟﺨﻄﻮط ا ﺴـﻄﺤﺔ ﻫﺬه أن ﺑﻌﺾ اﻟﻜﻮاﻛﺐ ﺗﺤﺖ ﻧﺒﺘﻮن ﻋﲆ اﻷﻗﻞ ﻛﺎﻧـﺖ ﻋـﲆ اﻷرﺟـﺢ ﻣﺤﺠﻮﺑـﺔ ﺑﺸــﺪة إﻣـﺎ ﺑﺎﻟﻐﻴﻮم أو اﻟﻀﺒ ﺎب ﻣﻤﺎ ﺟﻌﻞ ﺗﺤﺪﻳﺪ ﺗﺮﻛﻴﺒﻬﺎ ﺻﻌﺒﺎ وﻟﻜﻦ ﻗﺪ ﻳﻄـﺮح ﺗﺴـﺎؤل ـﺎذا ﻗﻤﻨـﺎ ﺑﺮﺻﺪ ﻫﺬا اﻟﻜﻮﻛﺐ TOI-421b ؟ ﻗﺎل ﻛ ﻴﻤﺒﺘﻮن " : ﻷﻧﻨﺎ ﻇﻨﻨﺎ أﻧﻪ رﺑﻤﺎ ﻻ ﻳﺤﺘﻮي ﻋﲆ ﺿﺒﺎب و اﻟﺴﺒﺐ ﻫﻮ وﺟﻮد ﺑﻴﺎﻧﺎت ﺳﺎﺑﻘﺔ ﺗُﺸ إﱃ أن اﻟﻜﻮاﻛﺐ اﻟﺘﻲ ﺗﻘﻊ ﻓـﻮق ﻧﻄـﺎق درﺟﺔ ﺣﺮارة ﻣﻌـ ﻗـﺪ ﺗﻜـﻮن أﻗـﻞ ﺣﺠﺒـ ﺎً ﻟﻠﻀﺒﺎب أو اﻟﺴﺤﺐ ﻣﻦ ﻏ ﻫﺎ . ﻫﺬا اﻻﻋﺘﻘـﺎد وﻓﺮ ﺑﺼﻴﺺ أﻣﻞ ﻟﻔﻬﻢ ﻏﻼﻓﻪ اﻟﺠﻮي ﺑﺸـﻜﻞ أﻓﻀــﻞ ﻣﻤــﺎ ﻗــﺪ ﻳ ﻜﺸــﻒ ﻋــﻦ ﺗﺮﻛﻴﺒﺘــﻪ وﺧﺼﺎﺋﺼ ﻪ اﻟﻔﺮﻳﺪة . ﻳﻮﻟﻴﻮ - ﺃﻏﺴﻄﺲ 2 0 2 5