Free Astronomy Magazine May-June 2024 ARABIC VERSION

or measurement technique relies upon the previous step for calibra- tion. But some astronomers suggested that, moving outward along the “secondrung,”thecosmicdistance ladder might get shaky if the Cepheid measurements become less accuratewithdistance.Suchinaccu- raciescouldoccurbecausethelight of a Cepheid could blend with that ofanadjacentstar–aneffectthat could become more pronounced with distance as stars crowd to- getherandbecomehardertodistin- guish from one another. Theobservationalchallengeisthat past Hubble images of these more distantCepheidvariableslookmore huddled and overlapping with neighboring stars at ever farther distancesbetweenusandtheirhost galaxies,requiringcarefulaccount- ingforthiseffect.Interveningdust further complicates the certainty of the measurements in visible light. Webbslicesthoughthedustand naturally isolates the Cepheids from neighboring stars because its visionis sharper than Hubble’s at infrared wavelengths. “Combining Webb and Hubblegives us the best of both worlds. We find that the Hubble measure- ments remain reliable as we climb farther along the cosmic distance ladder,” said Riess. ThenewWebbobservationsinclude fivehostgalaxiesofeightTypeIasu- pernovaecontainingatotalof1,000 Cepheids,andreachouttothefar- thest galaxy where Cepheids have beenwellmeasured–NGC5468–at a distance of 130 million light-years. “Thisspansthefullrangewherewe made measurements with Hubble. So, we’ve gone to the end of the secondrungofthecosmicdistance ladder,” saidco-authorGagandeep Anand of the Space Telescope Sci- ence Institute in Baltimore, which operatestheWebbandHubbletel- escopes for NASA. HubbleandWebb’sfurtherconfir- mation of the Hubble Tension sets up other observatories to possibly settlethemystery.NASA’supcoming NancyGraceRomanSpaceTelescope will do wide celestial surveys to studytheinfluenceofdarkenergy, the mysterious energy that is caus- ingtheexpansionoftheuniverseto accelerate.ESA’sEuclidobservatory, withNASAcontributions,ispursuing a similar task. At present it’s as though the dis- tance ladder observed by Hubble and Webb has firmly set an anchor point on one shoreline of a river, and the afterglow of the big bang observed by Planck’s measurement from the beginning of the universe issetfirmlyontheotherside.How theuniverse’sexpansionwaschang- ing in the billions of years between these two endpoints has yet to be directlyobserved. “Weneedtofind out if we are missing something on how to connect the beginning of theuniverseandthepresentday,” saidRiess.     ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 18 ﺗﻌﺘﻤﺪ ﻛﻞ درﺟﺔ ﰲ ﺳﻠﻢ ا ﺴﺎﻓﺎت اﻟﻜﻮﻧﻴﺔ أو ﺗﻘﻨﻴﺔ ﻗﻴﺎس ﻋﲆ اﻟﺨﻄﻮة اﻟﺴﺎﺑﻘﺔ ﻟﻠﻤﻌﺎﻳﺮة . ﻟﻜﻦ ﺑﻌﺾ ﻋﻠﻤﺎء اﻟﻔﻠﻚ اﻗﱰﺣـﻮا أن اﻟﺘﺤـﺮك ﻧﺤﻮ اﻟﺨﺎرج ﻋﲆ ﻃﻮل " اﻟﺪرﺟﺔ اﻟﺜﺎﻧﻴـﺔ " ﻗـﺪ ﻳﻬﺘـﺰ ﺳـﻠﻢ ا ﺴـﺎﻓﺔ اﻟﻜﻮﻧﻴـﺔ إذا أﺻـﺒﺤﺖ ﻗﻴﺎﺳﺎت اﻟﻨﺠﻮم ا ﺘﻐ ة اﻟﻘﻴﻔﺎوﻳ ﺔ أﻗﻞ دﻗـﺔ ﻣﻊ ا ﺴﺎﻓﺔ . ﻳﻤﻜﻦ أن ﺗﺤﺪث ﻣﺜﻞ ﻫـﺬه اﻟﺪﻗـﺔ ﻷن ﺿـﻮء اﻟﻨﺠﻢ ا ﺘﻐ اﻟﻘﻴﻔﺎوي ﻳﻤﻜﻦ أن ﻳﻤﺘﺰج ﻣـﻊ ﺿﻮء ﻧﺠﻢ ﻣﺠﺎور وﻫﻮ ﺗﺄﺛ ﻳﻤﻜﻦ أن ﻳﺼﺒﺢ أﻛﺜﺮ وﺿـﻮﺣًﺎ ﻣـﻊ ا ﺴـﺎﻓﺔ ﺣﻴـﺚ ﺗﺘﺠﻤـﻊ اﻟﻨﺠﻮم ﻣﻌ ﺎُ وﻳﺼﺒﺢ ﻣﻦ اﻟﺼﻌﺐ ﺗﻤﻴﻴﺰﻫﺎ ﻋﻦ ﺑﻌﻀﻬ ﺎ اﻟﺒﻌﺾ . اﻟﺘﺤﺪي اﻟﺬي ﻳﻮاﺟـﻪ ﻋﻤﻠﻴـﺔ اﻟﺮﺻـﺪ ﻫـﻮ أن ﺻﻮر ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﺴﺎﺑﻘﺔ ﻟﻬﺬه ا ﺘﻐ ات اﻟﻘﻴﻔﺎوﻳﺔ اﻟﺒﻌﻴﺪة ﺗﺒﺪو أﻛﺜﺮ ﺗﺠﻤﻌﺎ وﺗـﺪاﺧﻼ ﻣﻊ اﻟﻨﺠﻮم ا ﺠﺎورة ﻋﲆ ﻣﺴﺎﻓﺎت أﺑﻌﺪ ﺑﻴﻨﻨـﺎ وﺑ ا ﺠﺮات ا ﻀﻴﻔﺔ ﻟﻬﺎ ﻣﻤﺎ ﻳﺘﻄﻠﺐ ﺣﺴﺎﺑﺎ دﻗﻴﻘﺎ ﻟﻬﺬا اﻟﺘﺄﺛ . ﻳﺰﻳ ﺪ اﻟﻐﺒﺎر ا ﺘـﺪاﺧﻞ ﻣـﻦ ﺗﻌﻘﻴﺪ دﻗﺔ اﻟﻘﻴﺎﺳﺎت ﰲ اﻟﻀﻮء ا ﺮﺋﻲ . ﻳﻘﻄﻊ وﻳﺐ اﻟﻐﺒﺎر وﻳﻌﺰل اﻟﻨﺠﻮم اﻟﻘﻴﻔﺎوﻳﺔ ﺑﺸﻜﻞ ﻃﺒﻴﻌﻲ ﻋﻦ اﻟﻨﺠﻮم ا ﺠﺎورة ﻷن رؤﻳﺘﻪ أﻛﺜﺮ وﺿﻮﺣًﺎ ﻣﻦ رؤﻳﺔ ﻫﺎﺑـﻞ ﻋﻨـﺪ اﻷﻃـﻮال ا ﻮﺟﻴﺔ ﻟﻸﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء . " إن اﻟﺠﻤﻊ ﺑ ﺑﻴﺎﻧﺎت ﺗﻠﺴﻜﻮﺑﻲ وﻳﺐ وﻫﺎ ﺑـﻞ ﻳﻤﻨﺤﻨﺎ أﻓﻀﻞ ﻣﺎ ﰲ اﻟﻌﺎ . ﻗﺎل رﻳﺲ " : ﻟﻘﺪ وﺟﺪﻧﺎ أن ﻗﻴﺎﺳﺎت ﻫﺎﺑﻞ ﺗﻈﻞ ﻣﻮﺛﻮﻗﺔ ﻣﻊ ﺗﻘﺪﻣﻨﺎ ﻋﲆ ﻃﻮل ﺳـﻠﻢ ا ﺴـﺎﻓﺔ اﻟﻜﻮﻧﻴﺔ ." ﺗﺘﻀﻤﻦ ﻋﻤﻠﻴﺎت رﺻﺪ وﻳﺐ اﻟﺠﺪﻳﺪة ﺧﻤﺲ ﻣﺠﺮات ﻣﻀﻴﻔﺔ ﻟﺜﻤﺎﻧﻴـﺔ ﻣﺴـﺘﻌﺮات ﻋﻈﻤﻰ ﻣﻦ اﻟﻨـﻮع I ﺗﺤﺘـﻮي ﻋـﲆ إﺟﻤـﺎﱄ 1000 ﻧﺠ ﻢ ﺳﻴﻔﻴﺪي، وﺗﻤﺘﺪ إﱃ أﺑﻌـﺪ ﻣﺠـﺮة ﺣﻴﺚ ﺗﻢ ﻗﻴـﺎس اﻟﻨﺠـﻮم اﻟﻘﻴﻔﺎوﻳـﺔ ﺟﻴـﺪًا - NGC5468 - ﻋﲆ ﻣﺴﺎﻓﺔ ﺗﺒﻠـﻎ 130 ﻣﻠﻴـﻮن . ﺳﻨﺔ ﺿﻮﺋﻴﺔ ﻗﺎل ا ﺆﻟﻒ ا ﺸـﺎرك ﺟﺎﻏﺎﻧـﺪﻳﺐ أﻧﺎﻧـﺪ ﻣـﻦ ﻣﻌﻬﺪ ﻋﻠﻮم اﻟﺘﻠﺴﻜﻮب اﻟﻔﻀﺎﺋﻲ ﰲ ﺑـﺎﻟﺘﻴﻤ ﻮر اﻟﺬي ﻳﺪﻳﺮ ﺗﻠﺴـﻜﻮﺑﻲ وﻳـﺐ وﻫﺎﺑـﻞ ﻟﺼـﺎﻟﺢ وﻛﺎﻟﺔ ﻧﺎﺳﺎ " ﻳﻤﺘﺪ ﻫﺬا إﱃ اﻟﻨﻄﺎ ق اﻟﻜﺎﻣﻞ اﻟﺬي أﺟﺮﻳﻨﺎ ﻓﻴﻪ اﻟﻘﻴﺎﺳﺎت ﺑﺎﺳﺘﺨﺪام ﻫﺎﺑﻞ ﻟﻘﺪ ”.: وﺻﻠﻨﺎ إﱃ ﻧﻬﺎﻳﺔ اﻟﺪرﺟـﺔ اﻟﺜﺎﻧﻴـﺔ ﻣـﻦ ﺳـﻠﻢ ا ﺴﺎﻓﺔ اﻟﻜﻮﻧﻴﺔ “. ﻳﺆدي ﺗﺄﻛﻴﺪ ﻫﺎﺑﻞ ووﻳﺐ اﻹﺿﺎﰲ ﻟﺘﻄﻠﻊ ﻫﺎﺑﻞ إﱃ إﻧﺸﺎء ﻣﺮاﺻﺪ أﺧـﺮى ﻟﺤﻞ اﻟﻠﻐﺰ . ﺳـﻴﻘﻮم ﺗﻠﺴـﻜﻮب ﻧﺎﻧـ ﺄ روﻣـﺎن ﳼﻏـﺮﻳﺲ اﻟﻔﻀﺎﺋﻲ اﻟﻘﺎدم اﻟﺘﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ ﺑـﺈﺟ ﺮاء ﻣﺴﻮﺣﺎت ﺳﻤﺎوﻳﺔ واﺳﻌﺔ اﻟﻨ ﻄـﺎق ﻟﺪراﺳـﺔ ﺗﺄﺛ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ وﻫﻲ اﻟﻄﺎﻗﺔ اﻟﻐﺎﻣﻀـﺔ اﻟﺘﻲ ﺗﺴﺒﺐ ﺗﺴﺎرع ﺗﻮﺳﻊ اﻟﻜﻮن . و ﺗﺎﺑﻊ ﻣﺮﺻﺪ إﻗﻠﻴﺪس اﻟﺘﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ اﻟﻔﻀـﺎء اﻷوروﺑﻴﺔ، ﺑﻤﺴﺎﻫﻤﺎت وﻛﺎﻟـﺔ ﻧﺎﺳـﺎ، ﻣﻬﻤـﺔ . ﻣﻤﺎﺛﻠﺔ ﻻ ﺣﺎﻟﻴﺎً ﻳﺒﺪو اﻷﻣﺮ ﻛﻤﺎ ﻟـﻮ أن ﺳـﻠﻢ ا ﺴﺎﻓﺔ اﻟﺬي رﺻﺪه ﺗﻠﺴﻜﻮﺑﺎ و ﻫﺎﺑﻞ وﻳﺐ ﻗﺪ وﺿﻊ ﻧﻘﻄﺔ ﺛﺎﺑﺘﺔ ﻋﲆ أﺣﺪ ﺷـﻮاﻃﺊ اﻟﻨﻬـﺮ، ﻛﻤﺎ أن اﻟﺸﻔﻖ اﻟﻼﺣﻖ ﻟﻼﻧﻔﺠﺎر اﻟﻌﻈﻴﻢ اﻟﺬي رﺻﺪه ﻗﻴﺎس ﺑﻼﻧﻚ ﻣﻨﺬ ﺑﺪاﻳﺔ اﻟﻜﻮن ﻗـﺪ ﺗـﻢ ﺗﺜﺒﻴﺘﻪ ﺑﻘﻮة ﻋﲆ اﻟﺠﺎﻧﺐ اﻵﺧـﺮ . ﻛﻴـﻒ ﺗﻐـ ﺗﻮﺳﻊ اﻟﻜﻮن ﺧـﻼل ﻣﻠﻴـﺎرات اﻟﺴـﻨ ﺑـ ﻫﺎﺗ اﻟﻨﻘﻄﺘ اﻟﻨﻬﺎﺋﻴﺘ ﻟﻢ ﺗـﺘﻢ ﻣﺮاﻗﺒﺘـﻪ ﺑﺸﻜﻞ ﻣﺒﺎﴍ ﺑﻌﺪ . ﻗﺎل رﻳﺲ " : ﻧﺤﻦ ﺑﺤﺎﺟﺔ ﻌﺮﻓـﺔ ﻣـﺎ إذا ﻛﻨـﺎ ﺷﻴﺌًﺎ ﻟﻢ ﻧﻜﺘﺸﻔﻪ ﺣـﻮل ﻛﻴﻔﻴـﺔ اﻟـ ﺮﺑﻂ ﺑـ ﺑﺪاﻳﺔ اﻟﻜﻮن واﻟﻮﻗﺖ اﻟﺤﺎﱄ ". ﻳﻮﺟﺪ ﻓﻲ ﻣﺮﻛﺰ ﻫﺬﻩ ًــــﺎ إﻟــــﻰﺟﻨــــﺐ اﻟﺼــــﻮرﺟﻨ ﻓﺌــﺔ ﺧﺎﺻــﺔ ﻣــﻦ اﻟﻨﺠــﻮم ﺗُﺴـــﺘﺨﺪم ﻛﻌﻼﻣـــﺔ ﻣﻴـــﻞ ــــــــﺎسﻣﻌــــــــﺪل ﺗﻤــــــــﺪد ﻟﻘ ـــــــــــــﻢ ـــــــــــــﻮن، وﻫـــــــــــــﻮ ﻧ اﻟ ﻗ ﻔــــــــــــــــــــــﺎويﻣﺘﻐــــــــــــــــــــــ . اﻟﺼــــــــﻮرﺎن ﻣﺘﻘﻄّﻌﺘــــــــﺎن ﻟﻠﻐﺎ ﺔ؛ ﻷﻧﻬﻤﺎ ﻣُﻜ ﺎن ﺟـــﺪًا ﻓـــﻲﺿـــﻮء اﻟﻤﺠـــﺮة ـــــــــﺪة اﻟ ﻌ . ــــــــــﻞ وﺗﻤﺜــــــــــﻞ وﺣـــــــــــﺪة ﻜﺴـــــــــــﻞ ﻧ ﻤًـــــــــــﺎ واﺣـــــــــــــــــــﺪًا أو أﻛـــــــــــــــــــ إن . اﻟﺘﻘﻄﻬــــﺎ اﻟﺼــــﻮرة اﻟــــ ــــﺐ ﺗﻠﺴــــ ﻮبﺟــــ ﻤﺲو اﻟﻔﻀــﺎﺋﻲ أﻛــ وﺿـــﻮﺣﺎ ﻜﺜـــــــــــ ﻋﻨـــــــــــﺪ اﻷﻃــــــــــــﻮال ــــــﺔ ﻣــــــﻦ ــــــﺔ اﻟﻘﺮ اﻟﻤﻮﺟ اﻟ ﺔ اﻟﻘﺮ ﺔ ﻣﻦ اﻷﺷﻌﺔ ﺗﺤﺖ اﻟ ـ ﻤﺮاء ﻣﻦ ﺗﻠﺴ ﻮبﻫﺎﺑﻞ اﻟﻔﻀـﺎﺋﻲ ) ﻫـﻮ ﻓـﻲ اﻟﻤﻘـﺎم اﻷول ﺗﻠﺴـ ﻮب ﻌﻤـﻞ اﻟـﺬ ﺎﻷﺷـﻌﺔ ﻓـﻮق اﻟ ﻨ ـﺔ ﻔﺴـﺠ ﺔ اﻟﻤﺮ ( ــﺔ وﻣــﻦ ﺧـــﻼل ﺗﻘﻠﻴــﻞ اﻟﻔﻮﺿـــﻰ ﻣــﻦ ﺧـــﻼل رؤ ﺗﻠﺴـــ ﻮبﺟــ ﻤﺲ ـــﺐ اﻟﻮاﺿــﺤﺔ، ﻳـــ ز و اﻟــﻨ ﻢ اﻟﻘ ﻔـــﺎوي ﺸــ ﻞ أﻛـــ وﺿــﻮﺣﺎ ﻣﻤـــﺎ ﻳﺰ ــﻞ أي ـــﺎك ﻣﺤﺘﻤــﻞ ار . ﺗـــﻢ اﺳــﺘﺨﺪام ﺗﻠﺴــ ﻮبﺟــ ﻤﺲ ــﺐ ﻹﻟﻘــﺎء ﻧﻈــﺮة ﻋﻠــﻰﻋ ﻨــﺔ ﻣــﻦ و اﻟﻨﺠــﻮم اﻟﻤﺘﻐـــ ة ــ اﻟﻘ ﻔﺎو ﺔ وأﻛــﺪ دﻗــﺔ ارﺻــﺎد ﺗﻠﺴــ ﻮب ﺗ ﻫﺎﺑــﻞ اﻟﺴــﺎ ﻘﺔ اﻟــ ﻌﺘــ أﺳﺎﺳـــ ﺔ ﻟﻘ ﺎسﻣﻌﺪل ﺗﻮﺳﻊ اﻟ ﻮن وﻋﻤﺮﻩ ﺪﻗﺔ . ] NASA,ESA,CSA,STScI,AdamG.Riess(JHU,STScI [( - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2 0 2 4