Free Astronomy Magazine May-June 2023 ARABIC VERSION

MAY-JUNE 2023   Galactic immigration uncovered in Andromeda galaxy by NOIRLab − Charles Blue ver the course of billions of years, galaxies grow and evolve by forging new stars and merging with other galaxies through aptly named “galactic im- migration” events. Astronomers try to uncover the histories of these im- migration events by studying the motions of individual stars through- out a galaxy and its extended halo of stars and dark matter. Such cosmic archaeology, however, has only been possible in our own galaxy, the Way, until now. An international team of re- searchers has uncovered strik- ing new evidence of a large galactic immigration event in the Andromeda Galaxy, the Milky Way’s nearest large galactic neighbor. The new re- sults were made with the DOE’s Dark Energy Spectro- scopic Instrument (DESI) on the Nicholas U. Mayall 4- meter Telescope at Kitt Peak National Observatory, a Pro- gram of NSF’s NOIRLab. By measuring the motions of nearly 7500 stars in the inner halo of the Andromeda Galaxy, also known as Messier 31 (M31), the team discovered telltale patterns in the posi- tions and motions of stars that revealed how these stars began their lives as part of another galaxy that merged with M31 about 2 billion years ago. While such pat- terns have long been predicted by theory, they have never been seen with such clarity in any galaxy. “Our new observations of the Milky Way’s nearest large galactic neigh- bor, the Andromeda Galaxy, reveal evidence of a galactic immigration event in exquisite detail,” explained Arjun Dey, astronomer at NSF’s NOIRLab and the lead author of the paper presenting this research. “Al- though the night sky may seem un- changing, the Universe is a dynamic place. Galaxies like M31 and our Milky Way are constructed from the building blocks of many smaller galaxies over cosmic history.“ “We have never before seen this so clearly in the motions of stars, nor had we seen some of the structures that result from this merger,” said Sergey Koposov, an astrophysicist at the University of Edinburgh and coauthor of the paper. “Our emerging picture is that the history of the Andromeda Galaxy is similar to that of our own Galaxy, the Milky Way. The inner halos of both galax- ies are dominated by a single immigration event.” This research sheds light on not only the history of our galactic neighbors but also the history of our own galaxy. Most of the stars in the Milky Way’s halo were formed in another galaxy and later mi- grated into our own in a galactic merger 8–10 billion years ago. Studying the relics of a similar, but more recent, galaxy merger in M31 gives astronomers a window onto one of the major events in the Milky Way’s past. ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ ٣٤ اﻟﻜﺸﻒﻋﻦﻫﺠﺮة ﻣﺠﺮ ﺔ ﻓﻲﻣﺠﺮة اﻟﻤﺮأة اﻟﻤﺴﻠﺴﻠﺔ : ﻘﻠﻢ ﺗﺸﺎرﻟﺰ ﻟﻮ - ) ﻣﺨﺘ ﻧﻮﻳﺮﻻب ( ا ﺠﺮات ﺗﺘﻄﻮر ﻋﲆ وﺗﻨﻤﻮ ﻣـﺪار ﺑﻼﻳـ اﻟﺴﻨ ﻣـﻦ ﺧـﻼل ﺗﺸـﻜﻴﻞ ﻧﺠـﻮم ﺟﺪﻳـﺪة واﻻﻧﺪﻣﺎج ﻣﻊ ﻣﺠﺮات أﺧﺮى ﻣﻦ ﺧﻼل أﺣﺪاث ﺗﺴﻤﻰ " اﻟﻬﺠﺮة ا ﺠﺮﻳﺔ ." ﻳﺤﺎول ﻋﻠﻤﺎء اﻟﻔﻠـﻚ اﻟﻜﺸـﻒ ﻋـﻦ ﺗـﻮارﻳﺦ أﺣﺪاث اﻟﻬﺠﺮة ﻫﺬه ﻣﻦ ﺧﻼل دراﺳﺔ ﺣﺮﻛﺎت اﻟﻨﺠﻮم اﻟﻔﺮدﻳﺔ ﻋﱪ ﻣﺠﺮة وﻫﺎﻟﺘﻬـﺎ ا ﻤﺘـﺪة ﻣﻦ اﻟﻨﺠﻮم وا ﺎدة ا ﻈﻠﻤﺔ . وﻣـﻊ ذﻟـ ﻚ ﻓـﺈن ﻋﻠﻢ اﻵﺛﺎر اﻟﻜﻮﻧﻲ و ﻫﺬا ﻛﺎن ﻣﻤﻜﻨًﺎ ﻓﻘﻂ ﻋﱪ ﻣﺠﺮﺗﻨﺎ درب اﻟﺘﺒﺎﻧﺔ ﺣﺘﻰ اﻵ . ن ﻛﺸﻒ ﻓﺮﻳـﻖ اﻟﺒﺎﺣﺜ ﻋﻦ ﻣﻦ اﻟﺒﺎﺣﺜ ﻋﻦ أدﻟﺔ ﺟﺪﻳﺪة ﻣﺬﻫﻠﺔ ﻟﺤﺪث ﻫﺠﺮة ﻣﺠﺮ ي ﻛﺒ ﰲ ﻣﺠـﺮة ا ﺮاة ا ﺴﻠﺴـﻠﺔ ) أﻧﺪروﻣﻴـﺪا ( وﻫـﻲ أﻗﺮب ﻣﺠﺮة ﻛﺒ ة ﻣﺠﺎورة ﺠﺮﺗﻨـﺎ درب اﻟﺘﺒﺎﻧ ـﺔ . ﺗ ـﻢ إﺟــﺮاء ا ﻟﻨﺘ ـﺎﺋﺞ اﻟﺠﺪﻳ ـﺪة ﺑﺎﺳ ـﺘﺨﺪام أداة اﻟﺘﺤﻠﻴ ـﻞ اﻟﻄﻴﻔـــﻲ ﻟﻠﻄﺎﻗـــﺔ ا ﻈﻠﻤـــﺔ (DESI) اﻟﺘﺎﺑﻌــﺔ ﻟــﻮزارة اﻟﻄﺎﻗــﺔ اﻻﻣﺮﻳﻜﻴـﺔ وا ﺜﺒﺘـﺔ ﻋـﲆ ﺗﻠﺴـﻜﻮب ﻧﻴﻜﻮﻻس ﻳـﻮ ﻣﺎﻳـﺎل اﻟﺒـﺎﻟﻎ ارﺑﻌـﺔ أﻣﺘﺎر ا ﻮﺟﻮد ﰲ ﻣﺮﺻـﺪ ﻛﻴـﺖ ﺑﻴـﻚ اﻟﻮﻃﻨﻲ ﺑﻤﺨﺘﱪ ﻧﻮﻳﺮﻻب ﻌﻠﻟ ﻢ اﻟﻔﻠﻚ اﻷرﴈ واﻟﺒﺼ ـ ﺮي اﻟﻠـﻴﲇ واﻷﺷـﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ﺘاﻟ ﺎﺑﻊ ﺆﺳﺴﺔ اﻟﻌﻠﻮم اﻟﻮﻃﻨﻴﺔ ﻓ. ﻤﻦ ﺧﻼل ﻗﻴﺎس ﺣﺮﻛـﺎت ﻣﺎ ﻳﻘﺮب ﻣﻦ ٧٥٠٠ ﻧﺠـﻢ ﰲ اﻟﻬﺎﻟـﺔ اﻟﺪاﺧﻠﻴ ـﺔ ﺠ ـﺮة ا ــﺮأة ا ﺴﻠﺴــﻠﺔ وا ﻌﺮوﻓﺔ وا ﻌﺮوﻓﺔ أﻳﻀًﺎ ﺑﺎﺳﻢ ) ﻣﻴﺴﻴﻴﻪ ٣١ ( اﻛﺘﺸﻒ اﻟﻔﺮﻳﻖ أﻧﻤﺎﻃًﺎ ﻣﻠﻔﺘـﺔ ﰲ ﻣﻮاﻗـﻊ وﺣﺮﻛـﺎت اﻟﻨﺠﻮم اﻟﺘﻲ ﻛﺸﻔﺖ ﺑﺪأت ﻛﻴﻒ ﻫﺬه اﻟﻨﺠـﻮم ﺣﻴﺎﺗﻬﺎ ﻛﺠﺰء ﻣﻦ ﻣﺠﺮة اﺧﺮ ى اﻧﺪﻣﺠﺖ ﻣـﻊ ﻣﻴﺴﻴﻴﻪ ٣١ ﻣﻨﺬ ﺣﻮاﱄ ﻣﻠﻴﺎري ﺳﻨﺔ . وﺑﻴﻨﻤـﺎ ﺗﻨﺒﺎت اﻟﻨﻈﺮﻳﺔ ﺑ ﻤﺜﻞ ﻫﺬه اﻷﻧﻤﺎط ﻣﻨﺬ زﻣـﻦ ﻃﻮﻳﻞ إﻻ أﻧﻬﺎ ﻟﻢ ﺗﺸﺎﻫﺪ ﺑﻤﺜﻞ ﻫﺬا اﻟﻮﺿـﻮح ﰲ أي ﻣﺠـﺮة . أوﺿـﺢ " ارﺟـﻮن دي " ﻋـﺎﻟﻢ اﻟﻔﻠﻚ ﰲ ﻣﺨﺘﱪ ﻧﻮﻳﺮﻻب وا ﺆﻟـﻒ اﻟﺮﺋﻴـ ﴘ ـ ﻟﻠﻮرﻗﺔ اﻟﺘـﻲ ﺗﻘـﺪم ﻫـﺬا اﻟﺒﺤـﺚ : " ﺗﻜﺸـﻒ ﺗ" ﻜﺸﻒ أرﺻـﺎدﻧﺎ اﻟﺠﺪﻳـﺪة ﻷﻗـﺮب ﻣﺠـﺮة ﻣﺠﺮة ﻛﺒـ ة ﻣﺠـﺎورة ﺠـﺮة درب اﻟﺘﺒﺎﻧـﺔ أﻧﺪروﻣﻴﺪا ، ﻋﻦ دﻟﻴﻞ ﻋﲆ ﺣﺪث ﻫﺠﺮة ﻣﺠﺮ ي ﺑﺘﻔﺎﺻﻴﻞ راﺋﻌﺔ ." ﺑﺎﻟﺮﻏﻢ ﻣﻦ أن ﺳـﻤﺎء اﻟﻠﻴـﻞ ﻗـﺪ ﺗﺒـﺪو ﻏـ ﻓﺎن ﻣﺘﻐ ة اﻟﻜﻮن ﻣﻜﺎن دﻳﻨﺎﻣﻴﻜﻲ . ﻗـﺎل ﺳـ ﺟﻲ ﻛﻮﺑﻮﺳـﻮف ﻋــﺎﻟﻢ اﻟﻔﻴﺰﻳـﺎء اﻟﻔﻠﻜﻴﺔ ﺑﺠﺎﻣﻌﺔ إدﻧﱪة وأﺣﺪ ﻣﺆﻟﻔﻲ اﻟﻮرﻗﺔ اﻟﺒﺤﺜﻴﺔ " : ﻟﻢ ﻧﺮ ﻫﺬا ﻣﻦ ﻗﺒﻞ ﺑﻬﺬا اﻟﻮﺿﻮح ﰲ ﺣﺮﻛﺔ اﻟﻨﺠﻮم وﻟﻢ ﻧﺮ ﺑﻌـﺾ اﻟﻬﻴﺎﻛـﻞ اﻟﺘـﻲ ﻧﺘﺠﺖ ﻋﻦ ﻫﺬا اﻻ ." ﻧﺘﺠﺖ ﻋﻦ ﻫﺬا اﻻﻧﺪﻣﺎج ." ﺻـﻮرﺗﻨﺎ اﻟﻨﺎﺷﺌﺔ ﻫﻲ أن ﺗﺎرﻳﺦ ﻣﺠﺮة ا ـﺮأة ا ﺴﻠﺴﻠﺔ ) أﻧﺪروﻣﻴﺪا ( ﻣﺸﺎﺑﻪ ﻟﺘﺎرﻳﺦ ﻣﺠﺮﺗﻨﺎ درب اﻟﺘﺒﺎﻧﻪ . اﻟﻬـﺎﻻت اﻟﺪاﺧﻠﻴـﺔ ﻟﻜﻠﺘـﺎ ا ﺠـﺮﺗ ﻳﻬﻴﻤﻦ ﻋﻠﻴﻬﺎ ﺣﺪث ﻫﺠﺮة واﺣﺪ . ﻳﻠﻘﻲ ﻫﺬا اﻟﺒﺤﺚ اﻟﻀﻮء ﻟﻴﺲ ﻓﻘﻂ ﻋﲆ ﺗﺎرﻳﺦ ﺟ اﻧﻨﺎ ﻣﻦ ا ﺠﺮات وﻟﻜﻦ أﻳﻀًﺎ ﻋﲆ ﺗﺎرﻳﺦ ﻣﺠﺮﺗﻨـﺎ . ﺗﺸـﻜﻠﺖ ﻣﻌﻈﻢ اﻟﻨﺠﻮم ﰲ ﻫﺎﻟﺔ درب اﻟﺘﺒﺎﻧﺔ ﰲ ﻣﺠﺮة أﺧﺮى ﺛﻢ اﻧـﺪﻣﺠﺖ ﻻﺣﻘًـﺎ ﰲ ﻣﺠﺮﺗﻨﺎ ﰲ اﻧﺪﻣﺎج ﻣﺠﺮي ﻗﺒﻞ ٨-١٠ ﻣﻠﻴـﺎرات ﺳـﻨﺔ . إن درا ﺳـﺔ ﺑﻘﺎﻳـﺎ اﻧﺪﻣﺎج ﻣﺠﺮات ﻣﺸﺎﺑﻪ وﻟﻜﻦ أﺣـﺪث ﰲ ﻣﺠﺮة ﻣﻴﺴﻴﻴﻪ ٣١ ﻳﻤﻨﺢ اﻟ ﻌﻠﻤـﺎء ﻧﺎﻓﺬة ﻋﲆ أﺣﺪ اﻷﺣﺪاث اﻟﺮﺋﻴﺴـﻴﺔ ﰲ ﻣﺎﴈﻣﺠﺮة درب اﻟﺘﺒﺎﻧﺔ . - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2023 إن ــــﺎدة ﻋﻠﻤــــﺎء اﻟﻔﻠــــﻚ ﻓــــﻲ ﻘ ــــﺎﺣﺜ ﻛﺸــــﻒ ﻓﺮ ــــﻖ ﻣــــﻦ اﻟ ﻣﺨﺘــــ ﻧﻮﻳﺮﻻب اﻟﺘـﺎﺑﻊ ﻟﻤﺆﺳﺴـﺔ ـﺔ ـﺔ اﻻﻣﺮ ﻜ اﻟﻌﻠـﻮم اﻟﻮﻃﻨ ﻋـﻦ أدﻟـﺔ ــــﺪة ﻣﺬﻫﻠــــﺔ ﻋﻠــــﻰ اﻟﻬﺠــــ ﺟﺪ ـ ﺮة اﻟــــ ﻤﺎﻋ ﺔ ﻟﻠﻨﺠــــﻮم إﻟــــﻰ ﻣﺠــــﺮة اﻟﻤﺮأة اﻟﻤﺴﻠﺴﻠﺔ ) اﻧﺪروﻣ ﺪا ( . ﺗﻜﺸﻒ اﻷﻧﻤﺎط اﻟﻤﻌﻘﺪة ﻓﻲﺣﺮ ﺎت اﻟﻨﺠﻮم ﻋﻦ ﺗﺎر ﺦ ﻫﺠﺮة ﻣﺸـــــﺎ ﮫ ﺟـــــﺪًا ﻟ ﺘـــــﺎر ﺦ ﻣﺠـــــﺮة در اﻟ ﺘ ﺎﻧـــــﺔ . ـــــﺪﻳﻮ ﻠﺨـــــﺺ ﻫـــــﺬا اﻟﻔ اﻻﻛﺘﺸﺎف .