Free Astronomy Magazine July-August 2022 ARABIC VERSION

To understand how and when galaxies formed in the early Universe, as- tronomers look for distant galaxies. Because of the fi- nite speed of light, it takes time for the light from dis- tant objects to reach Earth. The light we see from an object 1 billion light-years away left that object 1 billion years ago and had to travel for 1 billion years to reach us. Thus studying distant galaxies lets us look back in time. The current record holder for the most distant galaxy isGN- z11, a galaxy billion light- Space Telescope. However, this dis- tance is about the limit of Hubble’s detection capabilities. HD1, a candidate object for the ear- liest/most-distant galaxy, was dis- covered from more than 1,200 hours of observation data taken by the Subaru Telescope, VISTA Tele- scope, UK Infrared Telescope, and Spitzer Space Telescope. “It was tough work to find HD1 out of more than 700,000 objects,” says Yuichi Harikane, who discovered HD1. “HD1’s red color matched the expected characteristics of a galaxy billion light-years away surpris- ingly well, giving me some goose- bumps when I found it.” The team conducted follow-up ob- servations using the Atacama Large Millimeter/submillimeter Array (ALMA) to confirm HD1’s distance. Akio Inoue, a professor at Waseda University, who led the ALMA ob- servations, says, “We found a weak signal at the frequency where an oxygen emission line was expected. The significance of the signal is 99.99%. If this signal is real, this is evidence that HD1 exists 13.5 billion light-years away, but we cannot be sure without a significance of 99.999% or more.” HD1 is very bright, suggesting that bright objects already existed in the Universe only 300 million years after the Big Bang. HD1 is hardly explained with cur- rent theoretical models of galaxy formation. Observational informa- tion on HD1 is limited, and its phys- ical properties remain a mystery. It is thought to be a very active star- forming galaxy, but it might be an active black hole. Either possibility makes it a fascinating object. In recognition of its astronomical im- portance, HD1 was selected as a tar- get for the Cycle 1 observations by the James Webb Space Telescope, launched last year. Yuichi Harikane, who is leading these observations, says, “If the spectroscopic observa- tion confirms its exact distance, HD1 will be the most distant galaxy ever recorded, 100 million light-years further away than GN-z11. We are looking forward to seeing the Uni- verse with the James Webb Space Telescope.”       ﻣﺴـﺎﻓﺔ 13.5 ﻣﻠﻴــﺎر ﺳـﻨﺔ ﺿــﻮﺋﻴﺔ وﻟﻜــﻦ ﻻ ﳝﻜﻨﻨــﺎ اﻟﺘﺄﻛــﺪ ﺑﻨﺴــﺒﺔ ٩٩.٩٩٩ ٪ أو أﻛــﱶ ." HD1 ﺔ ﺳـــﺎﻃﻌ ﻟﻠﻐﺎﻳـــﺔ ، ﳑـــﺎ ﻳﺸـــﲑ إﱃ أن اﻷﺟﺴﺎم اﻟﺴﺎﻃﻌﺔ ﻛﺎﻧﺖ ﻣﻮﺟـﻮدة ﺑﺎﻟﻔﻌـﻞ اﻟﻜـﻮن ﺑﻌــﺪ ٣٠٠ ﻣﻠﻴـﻮن ﺳــﻨ ﺔ ﻓﻘــﻂ ﺑﻌــﺪ ﺣــﺪوث اﻻﻧﻔﺠــﺎر اﻟﻌﻈــﻴﻢ . ﻳﺼــﻌﺐ ﺗﻔﺴــﲑ اﳌﺠــﺮة HD1 ﻣـﻦ ﺧـﻼل اﻟﻨﻤـﺎذج اﻟﻨﻈﺮﻳـﺔ اﳊﺎﻟﻴﺔ ﻟﺘﺸﻜﻴﻞ اﳌﺠـﺮات ﻣﻌﻠﻮﻣـﺎت اﻟﺮﺻـﺪ اﳋﺎﺻﺔ ﺑﺎﳌﺠﺮة ـ HD1 ﳏﺪودة ﺟﺪاً وﻻ ﺗﺰال ﺧﺼﺎﺋﺼــﻬ ﺎ ﺣــﱴ اﻵن ﻟﻐــﺰا ﻏﺎﻣﻀـــﺎً ﻟﻔﻬــﻢ ﻛﻴـﻒ وﻣـﱴ ﺷـﻜﻠﺖ اﳌﺠـﺮات اﻟﻜـﻮن اﳌﺒﻜـﺮ ، ﻳﺒﺤـﺚ ﻋﻠﻤــﺎء اﻟﻔﻠـﻚ ﻋـﻦ اﳌﺠـﺮا . ت اﻟﺒﻌﻴــﺪة ﺑﺴـ ﺐ اﻟﴪـﻋﺔ اﳌﺤـﺪودة ﻟﻠﻀـﻮء ﻳﺴـﺘﻐﺮق اﻟﻀﻮء ﻣﻦ اﻷﺟﺴﺎم اﻟﺒﻌﻴﺪة وﻗﺘًـﺎ ﻟﻠﻮﺻـﻮل إﱃ اﻷرض . ﻟﻘــﺪ ﺗـﺮك اﻟﻀـﻮء اﻟـﺬي ﻧـﺮاه ﻣـﻦ ﺟﺴــﻢ ﻋــﲆ ﺑﻌــﺪ ﻣﻠﻴــﺎر ﺳــﻨﺔ ﺿــﻮﺋﻴﺔ ﻫــﺬا اﳉﺴﻢ ﻗﺒﻞ ﻣﻠﻴﺎر ﺳﻨﺔ واﺿﻄﺮ ﻟﻠﺴـﻔﺮ ﳌـﺪة ﻣﻠ ﻴــﺎر ﺳــﻨﺔ ﻟﻠﻮﺻــﻮل إﻟﻴﻨــﺎ . وﺑﺎﻟﺘــﺎﱄ ﻓــﺈن دراﺳـﺔ اﳌﺠـﺮات اﻟﺒﻌﻴـﺪة ﺗﺘـﻴﺢ ﻟ ﻨـﺎ اﻟﻨﻈـﺮ إﱃ اﳌﺎﴈ . ﺻﺎﺣﺐ اﻟﺮﻗﻢ اﻟﻘﻴـﺎﳼ اﳊـﺎﱄ ﻷﺑﻌـﺪ ﳎـﺮة ﺗﺴـﻤﻰ GN-z11 وﻫـﻲ ﳎـﺮة ﻋـﲆ ﺑُ ﻌـﺪ ﻣﻠﻴــﺎر ﺳــﻨﺔ ﺿــﻮﺋ ﻴﺔ اﻛﺘﺸــﻔﻬﺎ ﺗﻠﺴــﻜﻮب ﻫﺎﺑـــﻞ اﻟﻔﻀـــﺎﰄ وﻣـــﻊ ذﻟـــﻚ ، ﻓـــﺈن ﻫـــﺬه اﳌﺴﺎﻓﺔ ﻫﻲ ﺣـﻮل ﺣـﺪود ﻗـﺪرات ﻫﺎﺑـﻞ ﻋـﲆ ــــــ " اﻟﻠـــﻮن اﻷﺣـــ ﻟــــ HD1 ﻳﻄــــــــــﺎﺑﻖ اﳋﺼــــــــــﺎﺋﺺ اﳌﺘﻮﻗﻌــ ﺔ ﳌﺠـﺮ ة ﻋــﲆ ﺑﻌـﺪ ﻣﻠﻴــــــﺎر ﺳــــــﻨﺔ ﺿــــــﻮﺋﻴﺔ ﺑﺸﻜﻞ ﻣﺪﻫﺶ ﳑﺎ ﺟﻌﻠﲏ أﺷﻌﺮ ﺑﺒﻌﺾ اﻟﻘﺸـﻌﺮﻳﺮة ﻋﻨـــﺪﻣﺎ وﺟـــﺪﺗﻬﺎ ". أﺟـــﺮى اﻟﻔﺮﻳـــﻖ أرﺻـــﺎد ﻣﺘﺎﺑﻌـــﺔ ﺑﺎﺳــــــﺘﺨﺪام ﻣﺼــــــﻔﻮﻓﺔ أﺗﺎﻛﺎﻣﺎ اﻟﻜﺒﲑة اﳌﻠﻴﻤﱰﻳﺔ / ﻣـــــــــــﺎ دون اﳌﻠﻴﻤـــــــــــﱰ ) ALMA ( ﻟﺘﺄﻛﻴﺪ ﻣﺴﺎﻓﺔ HD1 . ﻳﻘـــﻮل أﻛﻴـــﻮ إﻳﻨـــﻮ اﻷﺳــــــــﺘﺎذ ﺟﺎﻣﻌـــــــــﺔ واﺳــــــﻴﺪا ، اﻟــــــﺬي ﻗــــــﺎد ﻋﻤﻠﻴــــــــــــــــﺎت ALMA) ( " وﺟﺪﻧﺎ إﺷﺎرة ﺿﻌﻴﻔﺔ اﻟـــﱰدد ﺣﻴـــﺚ ﻛـــﺎن ﻣـــﻦ اﳌﺘﻮﻗﻊ وﺟﻮد ﺧﻂ اﻧﺒﻌﺎث اﻷﻛﺴــــــــﺠﲔ . أﻫﻤﻴــــــــﺔ اﻹﺷـــــــــــــﺎرة ٩٩.٩٩ ٪ إذا ﻛﺎﻧـــــﺖ ﻫـــــﺬه اﻹﺷـــــﺎرة ﺣﻘﻴﻘﻴــﺔ ﻓﻬــﺬا دﻟﻴــﻞ أن اﳌﺠـــــــــﺮة HD1 ﺗﺒﻌـــــــــﺪ ﻋــﲆ اﻟﻜﺸــﺎف . ﰎ اﻛﺘﺸــﺎف HD1 ، وﻫــﻮ ﺟﺴـــﻢ ﻣﺮﺷـــﺢ ﻟﻠﻤﺠــﺮة اﻷﻗــﺪم / اﻷﺑﻌــﺪ ﻣﻦ أﻛ ﱶ ﻣﻦ ١٢٠٠ ﺳﺎﻋﺔ ﻣﻦ ﺑﻴﺎﻧﺎت اﳌﺮاﻗﺒﺔ اﳌـــﺄﺧﻮذة ﺑﻮاﺳـــﻄﺔ ﺗﻠﺴـــﻜﻮب ﺳـــﻮﺑﺎرو ﺗﻠﺴـــﻜﻮب ﻓﻴﺴـــﺘﺎ ، ﺗﻠﺴـــﻜﻮب اﳌﻤﻠﻜـــﺔ اﳌﺘﺤـــــــﺪة ﺑﺎﻷﺷـــــــﻌﺔ ﺗﺤـــــــﺖ ا ﳊـــــــ اء وﺗﻠﺴــــﻜﻮب ﺳــــ ﻴﱱر اﻟﻔﻀــــﺎﰄ ﻳﻘــــﻮل ﻳﻮﻳﺘﴚـ ﻫﺎرﻳﻜـﺎن ، اﻟـﺬي اﻛﺘﺸـﻒ HD1 : " ﻛـﺎن ﻣـﻦ اﻟﺼـﻌﺐ اﻟﻌﺜـﻮر ﻋـﲆ HD1 ﻣـﻦ ﺑﲔ أﻛﱶ ﻣﻦ ﺳـﺒﻌﺔ آﻻف " ﺟﺴـﻢ ﻳُﻌﺘﻘـﺪ أ ﻧﻬــﺎ ﳎــﺮة ﻧﺸــﻄﺔ ﺟــﺪًا ﻟﺘﺸــﻜﻴﻞ اﻟﻨﺠــﻮم ﻟﻜﻨﻬـﺎ ﻗـﺪ ﺗﻜـﻮن ﺛﻘﺒًـﺎ أﺳـﻮدًا ﻧﺸـﻄًﺎ . ﻛـﻼ اﻻﺣﺘﻤـﺎﻟﲔ ﻳﺠﻌﻠـﻪ ﺟﺴـﻤﺎً . راﺋﻌًـﺎ اﻋﱰاﻓًـﺎ ﺑﺄﻫﻤﻴﺘﻬﺎ اﻟﻔﻠﻜﻴﺔ ، ﰎ اﺧﺘﻴﺎر HD1 ﻛﻬـﺪف ﻷرﺻﺎد اﻟـﺪورة اﻷوﱃ ﺑﻮاﺳـﻄﺔ ﺗﻠﺴـﻜﻮب ﺟﻴﻤﺲ وﻳـﺐ اﻟﻔﻀـﺎﰄ اﻟـﺬي أﻃﻠـﻖ اﻟﻌـﺎم اﳌﺎﴈ ﻳﻮﻳﺘﴚ ﻫﺎرﻳﻜﺎن اﻟﺬي ﻳﻘﻮد ﻫﺬ ه اﻷرﺻـــــﺎد ﻳﻘـــــﻮل " : إذا أﻛـــــﺪت اﳌﺮاﻗﺒـــــﺔ اﻟﻄﻴﻔﻴـــﺔ اﳌﺴــﺎﻓﺔ اﻟﺪﻗﻴﻘــﺔ ، ﻓـــﺈن HD1 ﺳـــﺘﻜﻮن أﺑﻌـــﺪ ﳎـــﺮة ﰎ ﺗﺴـــﺠﻴﻠﻬﺎ ﻋـــﲆ اﻹﻃﻼق ، ﻋﲆ ﻣﺴﺎﻓﺔ ﺑﻌﺪ ١٠٠ ﻣﻠﻴﻮن ﺳﻨﺔ ﺿﻮﺋﻴﺔ ﻣﻦ GN-z11 ﻧﺤﻦ ﻧﺘﻄﻠﻊ إﱃ رؤﻳـﺔ اﳉﺎﻣﻌـــﺔ ﻣـــﻊ ﺗﻠﺴـــﻜﻮب ﺟـــﻴﻤﺲ وﻳـــﺐ اﻟﻔﻀﺎﰄ . اﻟﻤﺠﺮات اﻟﻤ ﻜﺮة ﺟﺪاً اﻟﻤﺮﺷﺤﺔ وﺗﺎر ﺦ اﻟ ﻮن ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ٤٧