Free Astronomy Magazine November-December 2024 ARABIC VERSION

41 st g al ,” - r ni- - n ad never expected the data to be of such high quality thatwecouldsee somanydetailsof the convection on the stellar sur- face.” Starsproduceenergyintheir cores through nuclear fusion. This energy can be carried out towards thestar’ssurfaceinhuge,hotbub- bles of gas, which then cool down and sink — like a lava lamp. This mixing motion, known as convec- tion, distributes the heavy elements formed in the core, such as carbon and nitrogen, throughout the star. It is also thought to be responsible forthestellarwindsthatcarrythese elements out into the cosmos to build new stars and planets. Convectionmotionshadneverbeen trackedindetailinstarsotherthan the Sun, until now. By using ALMA, theteamwereabletoobtainhigh- resolution images of the surface of R Doradus over the course of a month. R Doradus is a red giant star, with a diameter roughly 350 times that of the Sun, located about 180 light- years away from Earth in the con- stellation Dorado. Its large size and proximity to Earth make it an ideal target for detailed observations. Furthermore, its mass is similar to that of the Sun, meaning R Doradusis likely fairly similar to how our Sun will look like in five billion years, once it becomes a red giant. “Convection creates the beautiful granularstructureseenonthesur- faceofourSun,butitishardtosee onotherstars,” addsTheoKhouri,a researcheratChalmerswhoisaco- author of the study. “With ALMA, wehavenowbeenabletonotonly directlyseeconvectivegranules— withasize75timesthesizeofour Sun! — but also measure how fast they move for the first time.” ThegranulesofRDoradusappearto move on a one-month cycle, which is faster than scientists expected based on how convection works in the Sun. “Wedon’tyetknowwhatistherea- sonforthedifference.Itseemsthat convection changes as a star gets older in ways that we don’t yet un- derstand,” says Vlemmings. Obser- vations like those now made of R Doradus are helping us to under- stand how stars like the Sun behave, even when they grow as cool, bigand bubbly as R Doradus is. “Itisspectacularthatwecannowdi- rectly image the details on the sur- face of stars so far away, and ob- serve physics that until now was mostly only observable in our Sun,” concludes Behzad Bojnodi Arbab, a PhD student at Chalmers who was alsoinvolvedinthestudy.    ﺗﻤﻜﻨـﺖ ﻣﺼـﻔﻮﻓﺔ ﻣﺮﺻــﺪ أﺗﺎ ﺎﻣـﺎ اﻟﻜﺒــ ﻟﻠﻤﻠ ﻤـ و ﺗﺤــﺖ اﻟﻤﻠ ﻤــ ( أﻟﻤـﺎ ) اﻟــــــ ﺸــــــﺎرك ﻓﻴﻬــــــﺎ اﻟﻤﺮﺻــــــﺪ اﻻوروﺑــــــﻲ ا ﻨــــــﻮﺑﻲ ﻣــــــﻦ اﻟﺘﻘــــــﺎط اﻟﺴــــــﻄﺢ اﻟﻔﻘﺎﻋﻲ ﻟﻠﻨ ﻢ ) آر دورادوس ( ﺘﻢ ﺗﺼﻮﻳﺮﻫـﺬﻩ وﻫﻲ اﻟﻤﺮة اﻷوﻟﻰ اﻟ ـاﻟ ﺤﺮﻛﺔ ﺎﻟﺘﻔﺼﻴﻞ ﻓﻲ ﻧ ﻢ ﻏ اﻟﺸﻤﺲ . ﻠﺨﺺﻫ ﺬا اﻟﻔ ﺪﻳﻮ اﻻﻛﺘﺸﺎف . ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 41 ﻳﻘﻮل ووﺗـﺮ ﻓﻠﻴﻤـﻨﺠ ﺲ أﺳﺘﺎذ ﰲ ﺟﺎﻣﻌﺔ ﺗﺸﺎ ﺮز ﻟﻠﺘﻜﻨﻮﻟﻮﺟﻴﺎ ﰲ اﻟﺴـﻮﻳﺪ، وا ﺆﻟﻒ اﻟﺮﺋﻴﴘ ﻟﻠﺪراﺳﺔ ا ﻨﺸﻮرة ﰲ ﻣﺠﻠﺔ ﻧﻴﺘﴩ : " ﻫﺬه ﻫﻲ ا ﺮة اﻷوﱃ اﻟﺘﻲ ﻳﻤﻜــﻦ ﻓﻴﻬــﺎ إﻇﻬــﺎر اﻟﺴﻄﺢ ا ﻟﻔﻘـﺎﻋﻲ ﻟـﻨﺠﻢ ﺣﻘﻴﻘﻲ ﺑﻬـﺬه اﻟﻄﺮﻳﻘـﺔ و ﻟﻢ ﻧﺘﻮﻗﻊ أﺑﺪ اً أن ﺗﻜـﻮن اﻟﺒﻴﺎﻧﺎت ﻋﺎﻟﻴـﺔ اﻟﺠـﻮدة ﻟﺪرﺟﺔ أﻧﻨﺎ ﻗﺪ ﻧﺮى اﻟﻜﺜ ﻣــﻦ ﺗﻔﺎﺻــﻴﻞ اﻟﺤﻤــﻞ اﻟﺤــﺮاري ﻋــﲆ ﺳــﻄﺢ اﻟــﻨﺠﻢ . ﺗﻨــﺘﺞ اﻟﻨﺠــﻮم اﻟﻄﻂ ﻧﻮﻓﻤﺒﺮ - ﺩﻳﺴﻤﺒﺮ 2 0 2 4 ﺎﻗــﺔ ﰲ أﻧﻮﻳﺘﻬـﺎ ﻣـﻦ ﺧـﻼل اﻻﻧـﺪﻣﺎج اﻟﻨﻮوي . ﻳﻤﻜﻦ ﻧﻘﻞ ﻫﺬه اﻟﻄﺎﻗﺔ ﻧﺤﻮ ﺳﻄﺢ اﻟ ﻨﺠﻢ ﰲ ﻓﻘﺎﻋﺎت ﻏﺎزﻳﺔ ﺿﺨﻤﺔ وﺳـﺎﺧﻨﺔ واﻟﺘﻲ ﺗﱪد ﺑﻌﺪ ذﻟﻚ وﺗﻐـﺮق ﻣﺜـﻞ ﻣﺼـﺒﺎح اﻟﺤﻤﻢ اﻟﱪﻛﺎﻧﻴﺔ . ﺗﻌﻤﻞ ﺣﺮﻛﺔ اﻟﺨﻠﻂ ﻫـ ﺬه ا ﻌﺮوﻓﺔ ﺑﺎﺳﻢ اﻟﺤﻤﻞ اﻟﺤﺮاري ﻋﲆ ﺗﻮزﻳـﻊ اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠـﺔ ا ﺘﻜﻮﻧـﺔ ﰲ اﻟﻨـﻮاة ﻣﺜـﻞ اﻟﻜﺮﺑ ـﻮن واﻟﻨﻴﱰوﺟــ ﰲ ﺟﻤﻴــﻊ أﻧﺤــﺎء اﻟﻨﺠﻢ . ﻳُﻌﺘﻘﺪ أﻳﻀ ﺎً أﻧﻬﺎ ﻣﺴﺆوﻟﺔ ﻋﻦ اﻟﺮﻳﺎح اﻟﻨﺠﻤﻴﺔ اﻟﺘﻲ ﺗﺤﻤﻞ ﻫﺬه اﻟﻌﻨﺎﴏ إﱃ اﻟﻜﻮن ﻟﺒﻨﺎء ﻧﺠﻮم وﻛﻮاﻛﺐ ﺟﺪﻳﺪة . ﻟـﻢ ﻳـﺘﻢ ﺗﺘﺒـﻊ ﺣﺮﻛـﺎت اﻟﺤﻤـﻞ اﻟﺤـﺮاري ﺑﺎﻟﺘﻔﺼﻴﻞ ﰲ اﻟﻨﺠﻮم اﻷﺧﺮى ﻏ اﻟﺸـﻤ ﺲ . ﺣﺘﻰ اﻵن ﺑﺎﺳﺘﺨﺪام ﻣﺮﺻﺪ أ ـﺎ ﺗﻤﻜـﻦ اﻟﻔﺮﻳـﻖ ﻣـﻦ اﻟﺤﺼﻮل ﻋﲆ ﺻﻮر ﻋﺎﻟﻴﺔ اﻟﺪﻗﺔ ﻟﺴ آر ) ﻄﺢ دورادوس ( ﻋﲆ ﻣﺪار ﺷﻬﺮ . ) آر دورادوس ( ﻫﻮ ﻧﺠﻢ أﺣﻤﺮ ﻋﻤﻼق ﻳﺒﻠـﻎ ﻗﻄﺮه ﺣـﻮاﱄ 350 ﺿـﻌﻒ ﻗﻄـﺮ اﻟﺸـﻤﺲ وﻳﺒﻌﺪ ﻣﺴﺎﻓﺔ ﺣﻮاﱄ 180 ﺳﻨﺔ ﺿﻮﺋﻴﺔ ﻣـﻦ اﻷرضﰲ ﻛﻮﻛﺒﺔ دورادو ) اﺑﻮ ﺳﻴﻒ ( . إن ﺣﺠﻤﻪ اﻟﻜﺒ وﻗﺮﺑﻪ ﻣﻦ اﻷرض ﻳﺠﻌﻠـﻪ ﻟﻸ ﺎً ﻓًﺎ ﻣﺜﺎﻟﻴ ﻫﺪ رﺻﺎد اﻟﺘﻔﺼﻴﻠﻴﺔ . ﻋﻼوة ﻋﲆ ذﻟﻚ ﻓﺈن ﻛﺘﻠ ﺘـﻪ ﻣﻤﺎﺛﻠـﺔ ﻟﻜﺘﻠـﺔ اﻟﺸﻤﺲ ﻣﻤﺎ ﻳﻌﻨﻲ أن اﻟﻨﺠﻢ ) آر دورادوس ( ﻣﻦ ا ﺮﺟﺢ أن ﻳﻜﻮن ﻣﺸﺎﺑﻬ ﺎً إﱃ ﺣﺪ ﻛﺒ ﺎ ﺳﺘﺒﺪو ﻋﻠﻴﻪ اﻟﺸﻤﺲ ﺑﻌﺪ ﺧﻤﺴﺔ ﻣﻠﻴـﺎرات ﺳـﻨﺔ ﺑﻤﺠـﺮد أن ﺗﺼــﺒﺢ ﻋﻤﻼﻗـ ﺎً أﺣﻤــﺮ . ــــــــــ ﻳﻀـﻴﻒ ﺛﻴـﻮ ﺧـﻮري اﻟﺒﺎﺣـﺚ ﰲ ﺟﺎﻣﻌـﺔ ﺗﺸﺎ ﺮز اﻟﺬي ﺷﺎرك ﰲ ﺗﺄﻟﻴﻒ اﻟﺪراﺳﺔ إن ": اﻟﺤﻤﻞ اﻟﺤﺮاري ﻳﺨﻠﻖ اﻟﺒﻨﻴﺔ اﻟﺤﺒﻴﺒﻴﺔ اﻟﺘـﻲ ﻧﺮاﻫﺎ ﻋﲆ ﺳﻄﺢ اﻟﺸﻤﺲ وﻟﻜﻦ ﻣﻦ اﻟ ﺼﻌﺐ رؤﻳﺘﻬﺎ ﻋﲆ اﻟﻨﺠﻮم اﻷﺧﺮى ." ﻳﻘـﻮل ﻓﻠﻴﻤﻨﺠـﺰ ": ﺑﻔﻀـﻞ ﺗﻠﺴـﻜﻮب أ ـﺎ أﺻﺒﺤﻨﺎ ﻗﺎدرﻳﻦ اﻵن ﻟ ﻴﺲ ﻓﻘﻂ ﻋﲆ رؤﻳـﺔ ﺣ ﺒﻴﺒﺎت اﻟﺤﻤـﻞ اﻟﺤـﺮاري ﺑﺸـﻜﻞ ﻣﺒـﺎﴍ ﺑﺤﺠﻢ 75 ﺿﻌﻒ ﺣﺠﻢ اﻟﺸﻤ ﺲ وﻟﻜﻦ أﻳﻀ ﺎً ﻗﻴﺎس ﻣﺪىﴎﻋﺘﻬﺎ ﻷول ﻣﺮة ". ﻳﺒ ـﺪو أن ﺣﺒﻴﺒ ـﺎت اﻟ ـﻨﺠﻢ ) آر دورادوس ( ﺗﺘﺤﺮك ﰲ دورة ﻣـﺪﺗﻬﺎ ﺷـﻬﺮ واﺣـﺪ وﻫـﻲ أﴎع ﻣﻤﺎ ﺗﻮﻗﻌﻪ اﻟﻌﻠﻤﺎء ﺑﻨﺎءً ﻋـﲆ ﻛﻴﻔ ﻴـﺔ ﻋﻤﻞ اﻟﺤﻤﻞ اﻟﺤﺮاري ﰲ اﻟﺸـﻤﺲ . ﻧﺤـﻦ ﻻ ﻧﻌ ﺮف ﺳ ﺒﺐ ﻫﺬا اﻻﺧﺘﻼف ، ﻳﺒﺪو أن اﻟﺤﻤـﻞ اﻟﺤﺮاري ﻳﺘﻐ ﻣﻊ ﺗﻘﺪم ﻋﻤﺮ اﻟﻨﺠﻢ ﺑﻄﺮق ﻢﻟ ﻧﻔﻬﻤ ." ﻬﺎ ﺑﻌﺪ ﺗﺴﺎﻋﺪﻧﺎ اﻷرﺻﺎد ﻣﺜﻞ ﺗﻠﻚ اﻟﺘﻲ ﺗﻢ إﺟﺮاؤﻫـﺎ اﻵن ﻋـﲆ ) آر دورادوس ( ﻋﲆ ﻓﻬـﻢ ﻛﻴﻔﻴـﺔ ﺗـ ـ ﴫف اﻟﻨﺠـﻮم ﻣﺜـﻞ اﻟﺸﻤﺲ، ﺣﺘﻰ ﻋﻨﺪﻣﺎ ﺗﻨﻤﻮ ﺑـﺎردة وﻛﺒـ ة وﻣﻔﻌﻤﺔ ﺑﺎﻟﻔﻘﺎﻋﺎت ﻣﺜﻞ ) آر دورادوس .( ﻳﺨﺘ ـﺘﻢ ﺑﻬ ـ ﺰاد ﺑﻮﺟﻨ ـﻮدي أرﺑ ـﺎب ﻃﺎﻟ ـﺐ اﻟﺪﻛﺘﻮراه ﰲ ﺟﺎﻣﻌﺔ ﺗﺸﺎ ﺮز واﻟﺬي ﺷـﺎرك أﻳﻀﺎً ﰲ اﻟﺪراﺳﺔ ﺑﺎﻟﻘﻮل " : إﻧﻪ ﻷﻣـﺮ ﻣـﺬﻫﻞ أن ﻧﺘﻤﻜﻦ اﻵن ﻣﻦ ﺗﺼﻮﻳﺮ اﻟﺘﻔﺎﺻـﻴﻞ ﻋـﲆ أ ﺳﻄﺢ اﻟﻨﺠﻮم اﻟﺒﻌﻴﺪة ﺑﺸﻜﻞ ﻣﺒﺎﴍ ورﺻﺪ اﻟﻔﻴﺰﻳﺎء اﻟﺘـﻲ ﻛﺎﻧـﺖ ﺣﺘـﻰ اﻵ ن ﻻ ﻳﻤﻜـﻦ رﺻﺪﻫﺎ إﻻ ﰲ اﻟﺸﻤﺲ .