Free Astronomy Magazine November-December 2023 ARABIC VERSION

ESA, ESA/Hubble, Roger Hubble sees the glittering globular cluster Terzan 12 by NASA/ESA Ray Villard Bethany Downer his colorful image of the glob- ular star cluster Terzan 12 is a spectacular example of how dust in space affects starlight com- ing from background objects. A globular star cluster is a conglom- eration of stars, arranged in a spher- oidal shape. Stars in globular clusters are bound together by gravity, with a higher concentration of stars to- wards the center. The Milky Way has about 150 ancient globular clusters at its outskirts. These clusters orbit around the galactic center, but far above and below the pancake-flat plane of our galaxy, like bees buzzing around a hive. The location of this globular cluster, deep in the Milky Way in the con- stellation Sagittarius, means that it is shrouded in gas and dust which absorb and alter the starlight ema- nating from Terzan 12. The cluster is about 15,000 light-years from Earth. This location leaves a lot of room for intervening interstellar dust particles between us and the cluster to scat- ter blue light, causing only the red- der wavelengths to come through to Earth. The interstellar dust clouds are mottled so that different parts of the cluster look redder than other parts along our line of sight. The brightest red stars in the photo are bloated, aging giants, many times larger than our Sun. They lie between Earth and the cluster. Only a few may actually be members of the cluster. The very brightest hot, blue stars are also along the line of sight and not inside the cluster, which only contains aging stars. Terzan 12 is one of 11 globular clus- ters discovered by the Turkish-Ar- menian astronomer Agop Terzan approximately a half-century ago. With its sharp vision, Hubble has revolutionized the study of globu- lar clusters ever since its launch in 1990. Hubble observations have shed light on the relation between age and composition in the Milky Way galaxy's innermost globular clusters.  ﻳﺮﺻﺪ " ﻫﺎﺑﻞ " اﻟﻌﻨﻘﻮد ا ﻟﻜﺮوياﻟﻤﺘﻸﻟﺊ ﺗ زان " " 48 : ﻘﻠﻢ رايﻓ ﻼرد و ﺑ ﺜﺎﻧﻲداوﻧﺮ اﻟﻤﺮﺻﺪ اﻷوروﺑﻲ اﻟـﺠﻨﻮﺑﻲ ﻫﺬه اﻟﺼﻮرة ا ﻠﻮﻧﺔ ﻟﻠﻌﻨﻘـﻮد اﻟﻨﺠﻤـﻲ اﻟﻜﺮوي ﺗ زان 12 ﻫﻲ ﻣﺜﺎل ﻣﺬﻫﻞ ﻟﻜﻴﻔﻴﺔ ﺗﺄﺛ اﻟﻐﺒﺎر ا ﻮﺟﻮد ﰲ اﻟﻔﻀﺎء ﻋـﲆ ﺿـﻮء اﻟﻨﺠـﻮم اﻟﻘـﺎدم ﻣـﻦ أﺟـﺮام ﰲ اﻟﺨﻠﻔﻴـﺔ . اﻟﻌﻨﻘﻮد اﻟﻨﺠﻤﻲ اﻟﻜﺮوي ﻋﺒﺎرة ﻋـﻦ ﺗﻜﺘـﻞ ﻣﻦ اﻟﻨﺠﻮم ﻣﺮﺗﺒﺔ ﻋﲆ ﺷﻜﻞ ﻛﺮوي . ﺗﺮﺗﺒﻂ اﻟﻨﺠــﻮم ا ﻮﺟــﻮدة ﰲ اﻟﻌﻨﺎﻗﻴــﺪ اﻟﻜﺮوﻳــ ﺔ ﺑﺒﻌﻀﻬﺎ اﻟﺒﻌﺾ ﻋﻦ ﻃﺮﻳﻖ اﻟﺠﺎذﺑﻴـﺔ ﻣـﻊ ﺗﺮﻛﻴﺰ أﻋﲆ ﻟﻠﻨﺠﻮم ﺑﺎﺗﺠﺎه ا ﺮﻛـﺰ . ﺗﺤﺘـﻮي ﻣﺠﺮة درب اﻟﺘﺒﺎﻧﺔ ﻋﲆ ﺣﻮاﱄ 150 ﻋﻨﻘـﻮد ﻛﺮوي ﻗﺪﻳﻢ ﰲ ﺿﻮاﺣﻴﻬﺎ . ﺗﺪو ر ﻫﺬه اﻟﻌﻨﺎﻗﻴﺪ ﺣﻮل ﻣﺮﻛﺰ ا ﺠﺮة وﻟﻜﻦ أﻋﲆ وأﺳﻔﻞ ﺑﻜﺜ ﻣـﻦ ا ﺴـﺘﻮى ا ﺴـﻄﺢ ﺠﺮﺗﻨﺎ ﻣﺜﻞ اﻟﻨﺤﻞ اﻟﺬي ﻳﻄﻦ ﺣﻮل . ﺘـﻪ ﺧﻠﻴ وﻣﻮﻗﻊ ﻫﺬا اﻟﻌﻨﻘﻮد اﻟﻜﺮوي ﰲ ﻋﻤﻖ ﻣﺠﺮة درب اﻟﺘﺒﺎﻧﺔ ﰲ ﻛﻮﻛﺒـﺔ اﻟﻘـﻮس ﻳﻌﻨـﻲ أﻧـﻪ ﻣﺤﺎط ﺑﺎﻟﻐﺎز واﻟﻐﺒﺎر اﻟﺬي ﻳﻤـﺘﺺ وﻳﻐـ ﺿﻮء اﻟﻨﺠﻮم ا ﻨﺒﻌﺚ ﻣﻦ ﺗ زان 12 . ﺒﻌـﺪ ﻳ اﻟﻌﻨﻘﻮد ﺣﻮاﱄ 15000 ﺳـﻨﺔ ﺿـﻮﺋﻴﺔ ﻋـﻦ . رضاﻷ ﻳﱰك ﻫـﺬا ا ﻮﻗـﻊ ﻣﺴـﺎﺣﺔ ﻛﺒـ ة ﻟﺘﺪاﺧﻞ ﺟﺰﻳﺌﺎت اﻟﻐﺒﺎر اﻟ ﺒ ﻧﺠﻤـﻲ ﺑﻴﻨﻨـﺎ وﺑ اﻟﻌﻨﻘﻮد ﻟﺘﺸﺘﻴﺖ اﻟﻀـﻮء اﻷزرق ﻣﻤـﺎ ﻳﺘﺴﺒﺐ ﰲ وﺻﻮل اﻷﻃـﻮال ا ﻮﺟﻴـﺔ اﻷﻛﺜـﺮ اﺣﻤﺮاراً ﻓﻘﻂ إﱃ اﻷرض . ﺗﻜﻮن ﺳﺤﺐ اﻟﻐﺒـﺎر ﺑـ اﻟﻨﺠ ـﻮم ﻣﺮﻗﺸ ـﺔ ﺑﺤﻴــﺚ ﺗﺒــﺪو اﻷﺟ ـﺰاء ا ﺨﺘﻠﻔﺔ ﻣﻦ اﻟﻌﻨﻘـﻮد أﻛﺜـﺮ اﺣﻤـﺮار اً ﻣـﻦ اﻷﺟﺰاء اﻷﺧﺮى ﻋﲆ ﻃﻮل ﺧﻂ رؤﻳﺘﻨﺎ . أ ﻊ اﻟﻨﺠﻮم اﻟﺤﻤﺮاء ﰲ اﻟﺼﻮ رة ﻫﻲ ﻋﻤﺎﻟﻘﺔ ﻣﻨﺘﻔﺨﺔ وﻣﺴـﻨﺔ أﻛـﱪ ﺑﻌـﺪة ﻣـﺮات ﻣـﻦ اﻟ ﺸﻤﺲ وﻫﻲ ﺗﻘﻊ ﺑ اﻷرضواﻟ ﻌﻨﻘﻮد وﻗﺪ ﻻﻳﻨﺘﻤـﻲ اﻻ ﻋـﺪد ﻗﻠﻴــﻞ ﻓﻘـﻂ أﻋﻀـﺎء ﰲ اﻟﻌﻨﻘﻮد . إن اﻟﻨﺠﻮم اﻟﺰرﻗﺎء اﻟﺴﺎﺧﻨﺔ اﻷﻛﺜﺮ ﺳﻄ ﻮﻋًﺎ ﺗﻮﺟﺪ أﻳﻀًﺎ ﻋـﲆ ﻃـﻮل ﺧـﻂ اﻟ ﺮوﻳـﺔ ﻣـﻦ اﻷرض ﺖ وﻟﻴﺴ داﺧﻞ اﻟﻌﻨﻘﻮد اﻟﺬي ﻳﺤﺘـﻮي ﻓﻘﻂ ﻋﲆ اﻟﻨﺠﻮم اﻟﻬﺮﻣﺔ . " ﺗ زان 12" ﻫـﻮ واﺣـﺪ ﻣـﻦ 12 ﻋﻨﻘـﻮدًا ﻛﺮوﻳًﺎ اﻛﺘﺸﻔﻬﺎ ﻋﺎﻟﻢ اﻟﻔﻠﻚ اﻟﱰﻛﻲ اﻷرﻣﻨﻲ أﻏﻮب ﺗ زان ﻣﻨﺬ ﻧﺼﻒ ﻗﺮن ﺗﻘﺮﻳﺒًﺎ . ﺑﻔﻀﻞ رؤﻳﺘﻪ اﻟﺤﺎدة أﺣﺪث ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ ﺛـﻮرة ﰲ دراﺳﺔ اﻟﻌﻨﺎﻗﻴﺪ اﻟﻜﺮوﻳﺔ ﻣﻨﺬ إﻃﻼﻗـﻪ اﱃ اﻟﻔﻀﺎء ﰲ ﻋﺎم 1990 . ﻟﻘﺪ ﺳﻠﻄﺖ أرﺻﺎد ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟﻀﻮء ﻋﲆ ا ﻟﻌﻼﻗﺔ ﺑ اﻟﻌﻤﺮ واﻟﱰﻛﻴـﺐ ﰲ اﻟﻌﻨﺎﻗﻴ ـﺪ اﻟﻜﺮوﻳ ـﺔ اﻟﺪاﺧﻠﻴ ـﺔ ﺠ ـﺮة درب اﻟﺘﺒﺎﻧﺔ . إن