Free Astronomy Magazine July-August 2023 ARABIC VERSION

view of researchers on the current evolutionary stage of Betelgeuse and on the consequent possibility that the star could explode in an un- expectedly near future. Among the recently published works on this topic, the most dis- cussed is undoubtedly the one signed by Hideyuki Saio, of Tohoku University, Japan, and three of his colleagues at the Université de Genéve, Switzerland. In early June, the team published an article in the Monthly Notices of the Royal As- tronomy Society that essentially states that Betelgeuse could ex- plode within a few decades. Saio and colleagues came to this conclu- sion (one of many admitted by cur- rent models and knowledge) by reinterpreting the importance of Betelgeuse’s two longest periods of variability. As readers will remem- ber, this star is a semiregular pulsat- ing variable, characterized by four different periods that overlap, gen- erating a rather complex light curve. The most relevant variation is asso- ciated with a pulsation with a pe- riod of 400-420 days, during which the star expands radially and then contracts. The other three periods, considered secondary, have dura- tions of approximately 2200, 230 and 185 days. Models of red super- giants such as Betelgeuse interpret these pulsations quite well and show that periods of a few hundred days are typically due to the fundamental pulsation, while the others are con- sidered harmonics of the fundamen- tal. By accepting the 400-420 day period as the fundamental period, the models place restrictions on the maximum size that Betelgeuse can reach before contracting again. Knowing theoretically the size ex- pected in reality and then measuring the apparent one in the sky, it should be easy to obtain a reliable estimate of the distance of the star. Unfortunately, although Betelgeuse ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 6 ﻳﻮﻟﻴﻮ - ﺃﻏﺴﻄﺲ 2 0 2 3 ﻫﻨﺎ ﺘﴫـﺳﻨﻘ ﻋـﲆ ﺗﺴـﻠﻴﻂ اﻟﻀـﻮء ﻋـﲆ وﺟﻬﺎت اﻟﻨﻈـﺮ ا ﺨﺘﻠﻔـﺔ ﻟﻠﺒـﺎﺣﺜ ﺣـﻮل ا ﺮﺣﻠـﺔ اﻟﺘﻄﻮرﻳـﺔ اﻟﺤﺎﻟﻴ ـﺔ ﻣـﻦ ﻣﻨﻜ ـﺐ اﻟﺠﻮزاء وﻣﺎ ﻳﱰﺗﺐ ﻋﲆ ذﻟﻚ ﻣﻦ اﺣﺘﻤﺎل أن ﻳﻨﻔﺠﺮ اﻟﻨﺠﻢ ﰲ ا ﺴﺘﻘﺒﻞ اﻟﻘﺮﻳـﺐ ﺑﺸـﻜﻞ ﻏ ﻣﺘﻮﻗﻊ إن . ﻣﻦ ﺑ اﻷﻋﻤﺎل اﻟﺘﻲ ﻧُﴩت ﻣﺆﺧﺮًا ﺣﻮل ﻫﺬا ا ﻮﺿﻮع ﻓﺈن أﻛﺜﺮ اﻷﻋﻤﺎل اﻟﺘﻲ ﺗﻤﺖ ﻣﻨﺎﻗﺸﺘﻬﺎ ﻫﻲ ﺑﻼ ﺷﻚ ﺗﻠﻚ اﻟﺘـﻲ ﻗـﺎم ﺑﻬـﺎ ﻫﻴـﺪﻳﻮﻛﻲ ﺳـﺎﻳﻮ ﻣـﻦ ﺟﺎﻣﻌـﺔ ﺗﻮﻫﻮﻛـﻮ ﺑﺎﻟﻴﺎﺑـﺎن وﺛﻼﺛـﺔ ﻣـﻦ زﻣﻼﺋـﻪ ﰲ ﻴـ ﻌﺔ ﺟﻨ ـﺟﺎﻣ . ﻒ ﺑﺴﻮﻳﴪا ﰲ أواﺋـﻞ ﺷـﻬﺮ ﻳﻮﻧﻴﻮ ـﻧﺸ ﺮ اﻟﻔﺮﻳـ ﻖ ﻣﻘـﺎﻻً ﰲ اﻻﺷـﻌﺎرات اﻟﺸــﻬﺮﻳﺔ ﻟﻠﺠﻤﻌﻴـﺔ ا ﻠﻜﻴـﺔ ﻟﻌﻠـﻢ اﻟﻔﻠـﻚ ﻳﺘﺤـﺪث ﺑﺸـﻜﻞ أﺳـﺎﳼﻋـﲆ أن ﻣﻨﻜـﺐ اﻟﺠﻮزاء ﻳﻤﻜﻦ أن ﻳﻨﻔﺠﺮ ﰲ ﻏﻀﻮن ﺑﻀـﻌﺔ . د ﻋﻘــﻮ ﺗﻮﺻـﻞ ﺳــﺎﻳﻮ وزﻣ ـﻼؤه إﱃ ﻫــﺬا اﻻﺳﺘﻨﺘﺎج ) واﺣﺪ ﻣﻦ اﻟﻌﺪﻳـﺪ ﻣـﻦ اﻟﻨﻤـﺎذج ا ﻌﱰف ﺑﻬﺎ وا ﻌﺮﻓﺔ اﻟﺤﺎﻟﻴـﺔ ( ﻣـﻦ ﺧـﻼل إﻋﺎدة ﺗﻔﺴ أﻫﻤﻴﺔ ﻣﻨﻜﺐ اﻟﺠﻮز اء اﻷﻃﻮل ﻓﱰﺗ ﻣﻦ اﻟﺘﺒﺎﻳﻦ . ﻛﻤﺎ ﺳﻴﺘﺬﻛﺮ اﻟﻘﺮاء ﻓﺈن ﻫﺬا اﻟﻨﺠﻢ ﻋﺒﺎرة ﻋﻦ ﻣﺘﻐـ ﻧـﺎﺑﺾ ﺷـﺒﻪ داﺋﺮي ﻳﺘﻤﻴﺰ ﺑﺄرﺑﻊ ﻓـﱰات ﻣﺨﺘﻠﻔـﺔ ﻣﻤـﺎ ﻳﺆدي إﱃ ﺗﻜﻮﻳﻦ ﻣﻨﺤﻨﻰ ﺿـﻮﺋﻲ ﻣﻌﻘـﺪ إﱃ . ﺣﺪ ﻣﺎ ﻳﺮﺗﺒﻂ اﻻﺧﺘﻼف اﻷﻛﺜﺮ ﺻﻠﺔ ﺑﻨـﺒﺾ ﻣﺪﺗﻪ 400 - 420 ﻮﻣًﺎ ﻳ ﻳﺘﻢ ﺧﻼﻟﻬﺎ ﺗﻮﺳـ ﻊ اﻟﻨﺠﻢ ﺷﻌﺎﻋﻴًﺎ ﺛ ﻢ ﻳﺘﻘﻠﺺ ا. ﻟﻔﱰات اﻟـﺜﻼث اﻷﺧﺮى اﻟﺘﻲ ﺗﻌﺘﱪ ﺛﺎﻧﻮﻳﺔ ﻟﻬﺎ ﻓﱰات ﺗﻘﺎرب 2200 و 230 و 185 إن . ﻳﻮﻣًﺎ ﻧﻤـﺎذج ﻣـﻦ اﻟﻌﻤﺎﻟﻘﺔ اﻟﺤﻤﺮاء ﻣﺜﻞ ﻣﻨﻜﺐ اﻟﺠﻮزاء ﺗﻔﴪ ﻫﺬه اﻟﻨﺒﻀﺎت ﺑﺸﻜﻞ ﺟﻴﺪ وﺗﻈﻬﺮ أن ﻓﱰات ﻣﻦ ﺑﻀﻊ ﻣﺌﺎت ﻣﻦ اﻷﻳ ﺎم ﺗﺮﺟـﻊ ﻋـﺎدة إﱃ اﻟﻨــﺒﺾ اﻷﺳــﺎﳼ ﰲ ﺣــ أن اﻵﺧــﺮﻳﻦ ﻳﻌﺘﱪون اﻟﺘﻮاﻓﻘﻴﺎت اﻷ . ﺳﺎﺳﻴﺔ ﺑﻘﺒﻮل ﻓ ﱰة 400 - 420 ﻳﻮﻣًﺎ ﻛﻔـﱰة أﺳﺎﺳـﻴﺔ ﺗﻀـﻊ اﻟﻨﻤﺎذج ﻗﻴﻮدًا ﻋﲆ اﻟﺤﺠـﻢ اﻷﻗـ ـ ﴡ اﻟـﺬي ﻳﻤﻜﻦ أن ﻳﺼﻞ إﻟﻴﻪ ﻣﻨﻜـﺐ اﻟﺠـﻮزاء ﻗﺒـﻞ اﻟﺘﻌﺎﻗﺪ ﻣﺮة أﺧﺮى . ﻣﻊ اﻟﻌﻠﻢ ﻧﻈﺮﻳًﺎ ﺑﺎﻟﺤﺠﻢ ا ﺘﻮﻗﻊ ﰲ اﻟﻮاﻗﻊ ﺛﻢ ﻗﻴﺎس اﻟﻘﺪر اﻟﻈﺎﻫﺮ ي ﰲ اﻟﺴـﻤﺎء ﻳﺠـﺐ أن ﻳﻜـﻮن ﻣـﻦ اﻟﺴـﻬﻞ اﻟﺤﺼﻮل ﻋﲆ ﺗﻘﺪﻳﺮ ﻣ ﻮﺛﻮق ﺴﺎﻓﺔ اﻟﻨﺠﻢ . ) ﻂ ﻌﺪ ﻣﺨﻄ ﻫﺮﺰﺷ وﻧﺞ – ( راﺳﻞ أﺣﺪ أﻫﻢ اﻷدوات ﻓـﻲ دراﺳـﺔ ﺗﻄـﻮراﻟﻨﺠـﻮم . ﺗـﻢ ﺗﻄـﻮﻳﺮﻩ ﺸـ ﻞ ﻣﺴﺘﻘﻞ ﻓﻲ أواﺋﻞ اﻟﻘﺮن اﻟﻌﺸﺮ ﻦ ﺑﻮاﺳﻄﺔ إ ﻨـﺎرﻫﺮﺰﺳـ وﻧﻎ و ﻫـ ي ﻧـﻮرﺲراﺳـﻴﻞ وﻫـﻮ ﻳﻮﺿـﺢ درﺟـــﺔ ﺣـــﺮارة اﻟﻨﺠـــﻮم ﻣﻘﺎﺑـــﻞ ﻟﻤﻌﺎﻧﻬـــﺎ أو ﻟـــﻮن اﻟﻨﺠـــﻮم ) أو اﻟﻨـــﻮع اﻟﻄ ﻔـــﻲ ( ﻣﻘﺎﺑـــﻞ ﻫﺎ ﻗَـــﺪْر اﻟﻤﻄﻠـــﻖ ) اﻟﻘﺪر اﻟﻈﺎﻫﺮي اﻟﻤﺮﺻﻮد ( اﻟﻤﻌﺮوف أ ﻀًﺎ ﺎﺳﻢ ر ﻘَﺪْ اﻟ اﻟﻠﻮﻧ (.ﻲ اﻟﻌﻤﻼق اﻷ ﻤﺮ واﻟﻨﺠﻮم اﻟ ـ ﻤﺮاء اﻟﻌﻤﻼﻗﺔ ﺗﻮﺟﺪ ـﺎﻧﻲ اﻟﺮﺳـﻢ اﻟﺒ ﻓﻲ أﻋﻠـﻰ ﻤـ . ـﺎ ﻫـﺬا أﻧﻬـﺎ ﻳﺨ أﻛــ إﺷــﺮاﻗًﺎ ﻣـــﻦ ﻧﺠــﻮم اﻟﺘﺴﻠﺴــﻞ اﻟﺮ ﺴـــﻲوﻟﻜﻨﻬــﺎ أ ﻀًــﺎ أﻛـــ ا ﻤــﺮارًا وﺑــﺮودة و ﺘﺗ ﺎ ﻫـــﺬا ﻷﻧﻬــ ﻮﺳـــﻊ د وﺗـــ ﺗ ﻋﻨـــﺪﻣﺎ ـــﺔ ﻣـــﻦ ﺣ ﺎﺗﻬـــ ﺼـــﻞ إﻟـــﻰ اﻟﻤﺮاﺣـــﻞ اﻟﻨﻬﺎﺋ ﺎ وﻣـــﻊ ذﻟـــﻚ ﻧﻈـــﺮًا ﻟـــ ـ ﺤ ﻤﻬﺎ اﻟﻜﺒـــ ﻓﺈﻧﻬـــﺎ ﺗﻈـــﻞ ﻣﺸﺮﻗﺔ ﺟﺪًا ] . ﺟﺎﻣﻌﺔ ﻟ ﻔﺮﻮل ﺟﻮن ﻣﻮرس [.