Free Astronomy Magazine March-April 2023 ARABIC VERSION

Star forming region NGC 346 seen by Webb by NASA/ESA/CSA Matthew Brown Christine Pulliam GC 346, one of the most dy- namic star-forming regions in nearby galaxies, is full of mys- tery. Now, it is less mysterious with new findings from NASA’s James Webb Space Telescope. NCG 346 is located in the Small Magellanic Cloud (SMC), a dwarf galaxy close to our Milky Way. The SMC contains lower concentrations of elements heavier than hydrogen or helium, which astronomers call metals, com- pared to the Milky Way. Since dust grains in space are composed mostly of metals, scientists expected there would be low amounts of dust, and that it would be hard to detect. New data from Webb reveals the oppo- site. Astronomers probed this region because the conditions and amount of metals within the SMC resemble those seen in galaxies billions of years ago, during an era in the uni- verse known as “cosmic noon,” when star formation was at its peak. Some 2 to 3 billion years after the big bang, galaxies were forming stars at a furious rate. The fireworks of star formation hap- pening then still shape the galaxies we see around us today. “A galaxy during cosmic noon wouldn’t have one NGC 346 like the Small Magel- lanic Cloud does; it would have thou- sands of star-forming regions like this one,” said Margaret Mixer, an astronomer at the Universities Space Research Association and principal investigator of the research team. “But even if NGC 346 is now the one and only massive cluster furiously forming stars in its galaxy, it offers us a great opportunity to probe condi- tions that were in place at cosmic noon.” By observing protostars still in the process of forming, re- searchers can learn if the star forma- tion process in the SMC is different from what we observe in our own Milky Way. Previous infrared studies of NGC 346 have focused on proto- stars heavier than about 5 to 8 times the mass of our Sun. “With Webb, we can probe down to lighter- weight protostars, as small as one tenth of our Sun, to see if their for- mation process is affected by the lower metal content,” said Olivia Jones of the United Kingdom As- tronomy Technology Centre, Royal Observatory Edinburgh, a co-investi- gator on the program. As stars form, they gather gas and dust, which can look like ribbons in Webb imagery, from the surround- ing molecular cloud. The material collects into an accretion disk that feeds the central protostar. As- tronomers have detected gas around protostars within NGC 346, but Webb’s near-infrared observations mark the first time they have also de- tected dust in these disks. “We’re seeing the building blocks, not only of stars, but also potentially of planets,” said Guido De Marchi of the European Space Agency, a co-in- vestigator on the research team. “And since the Small Magellanic Cloud has a similar environment to galaxies during cosmic noon, it’s pos- sible that rocky planets could have formed earlier in the universe than we might have thought.” The team also has spectroscopic observations from Webb’s NIRSpec instrument that they are continuing to analyze. These data are expected to provide new insights into the material accret- ing onto individual protostars, as well as the environment immedi- ately surrounding the protostar.      ﻠﺔ ﻣﺠ Astronomy ﺎﻟﻌﺮ ﺔ ١٦ ﺗﻠﺴ ﻮبو ﺐ ﻳﺮﺻﺪ ﻣﻨﻄﻘﺔ ﺗﺸ ﻞ اﻟﻨﺠﻮم NGC 344 : ﻘﻠﻢ ﺑﻮﻟ ﺎم ﻣﺎﺛﻴﻮ ﺑﺮاون و ﻛﺮﺴﺘ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ NGC 346 ﺗﻌﺘﱪ واﺣﺪة ﻣـﻦ أﻛﺜـﺮ ﻣﻨﺎﻃﻖ ﺗﺸﻜﻞ اﻟﻨﺠﻮم دﻳﻨﺎﻣﻴﻜﻴﺔ ﰲ ا ﺠﺮات اﻟﻘﺮﻳﺒﺔ ا ﻠﻴﺌﺔ ﺑﺎﻟﻐﻤﻮض ، أﻣﺎ اﻵن أﺻـﺒﺤ ﺖ أﻗــﻞ ﻏﻤﻮﺿًـﺎ ﻣـﻊ اﻟﻨﺘـﺎﺋﺞ اﻟﺠﺪﻳـﺪة ﻣـﻦ ﺗﻠﺴـﻜﻮب ﺟـﻴﻤﺲ وﻳـﺐ اﻟﻔﻀـﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟﻨﺎﺳﺎ . ﺗﻮﺟﺪ ﻣﻨﻄﻘـﺔ NCG 346 ﰲ ﺳـﺤﺎﺑﺔ ﻣﺎﺟﻼن اﻟﺼﻐﺮى وﻫﻲ ﻣﺠﺮة ﻗﺰﻣـﺔ ﻗﺮﻳﺒـﺔ ﻣﻦ ﻣﺠﺮﺗﻨﺎ درب اﻟﺘﺒﺎﻧـﺔ ، ﺗ ﺤﺘـﻮي ﺳـﺤﺎﺑﺔ ﻣﺎﺟﻼن اﻟﺼـﻐﺮى ﻋـﲆ ﺗﺮﻛﻴـﺰات أﻗـﻞ ﻣـﻦ اﻟﻌﻨﺎﴏ اﻷﺛﻘﻞ ﻣﻦ اﻟﻬﻴﺪروﺟ أو اﻟﻬﻠﻴـﻮم وا ﻟﺘﻲ ﻳﺴﻤﻴﻬﺎ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ا ﻌﺎدن ﺑﺎ ﻘﺎرﻧﺔ ﻣﻊ درب اﻟﺘﺒﺎﻧﺔ . ﻧﻈﺮًا ﻷن ﺣﺒﻴﺒﺎت اﻟﻐﺒـﺎر ﰲ ا ﻟﻔﻀﺎء ﺗﺘﻜﻮن ﰲ اﻟﻐﺎﻟﺐ ﻣـﻦ ﻣﻌـﺎدن ﻓﻘـﺪ ﺗﻮﻗﻊ اﻟﻌﻠﻤﺎء وﺟﻮد ﻛﻤﻴﺎت ﻗﻠﻴﻠﺔ ﻣﻦ اﻟﻐﺒﺎر وأﻧﻪ ﺳﻴﻜﻮن ﻣﻦ اﻟﺼﻌﺐ اﻛﺘﺸﺎﻓﻬﺎ . ﺗﻜﺸﻒ اﻟﺒﻴﺎﻧﺎت اﻟﺠﺪﻳﺪة ﻣﻦ ﺗﻠﺴﻜﻮب وﻳـﺐ ﻋﻜـﺲ ذﻟﻚ ، ﻓﻘﺪ ﺳﱪ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻫﺬه ا ﻨﻄﻘﺔ ﻷن ﻇﺮوف وﻛﻤﻴﺔ ا ﻌﺎدن داﺧﻞ ﺳﺤﺎﺑﺔ ﻣﺎﺟﻼن اﻟﺼﻐﺮى ﺗﺸﺒﻪ ﺗﻠﻚ اﻟﺘﻲ ﰲ ا وﺟـﺪت ﺠـﺮات ﻣﻨﺬ ﻣﻠﻴﺎرات اﻟﺴﻨ ﺧﻼل ﺣﻘﺒـﺔ ﰲ اﻟﻜـ ﻮن ﺗﻌﺮف ﺑﺎﺳﻢ " اﻟﻈﻬ ة اﻟﻜﻮﻧﻴﺔ " ﻋﻨﺪﻣ ﺎ ﻛـﺎن ﺗﻜﻮﻳﻦ اﻟﻨﺠﻮم ﰲ ذروﺗﻪ ﺑﻌـﺪ ﺣـﻮاﱄ ٢ إﱃ ٣ ﻣﻠﻴﺎرات ﺳﻨﺔ ﻣﻦ اﻻﻧﻔﺠﺎر اﻟﻌﻈـﻴﻢ ، ﻛﺎﻧـﺖ ا ﺠ ـﺮات ﺗﺸ ـﻜﻞ اﻟﻨﺠ ـﻮم ﺑﻤﻌ ـﺪل ﻫ ـﺎﺋﺞ NGC 346 اﻟﻤﻮﺿﺤ ﺔ ﻫﻨﺎ ﻓﻲﻫﺬﻩ اﻟﺼﻮرة اﻟﺘﻘﻄﺖ ﺑﻮاﺳﻄﺔ ﺗﻠﺴ ﻮبﺟ ﻤﺲو ﺐ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳـــﺎ وﻫـــ ﻲ ـــﺔ ـــﺔ د ﻨﺎﻣ ﻜ ـــﺎرة ﻋـــﻦ ﻣ ﻤﻮﻋـــﺔ ﻧ ﻤ ﻋ ﺗﻮﺟـــﺪ داﺧـــﻞﺳـــﺪ ﻢ ﻳ ﻌـــﺪ ٢٠٠ أﻟـــﻒﺳـــﻨﺔ ﺿـــﻮ . ﺋ ﺔ ﻜﺸــﻒ ﺗﻠﺴـــ ﻮب ـــﺪ ﻣـــﻦ ﻟ ﻨـــﺎت اﻟ ﻨــﺎء ـــﺐ ﻋـــﻦ وﺟــﻮد اﻟﻌﺪ و ـــﺎن ﻣﺘﻮﻗﻌًــﺎ ﻓـــﻲ اﻟﺴـــﺎﺑﻖ أﻛـــ ﻣﻤـــﺎ ﻟـــ ﺲ ﻓﻘــﻂ ﻟﻠﻨﺠـــﻮ م وﻟﻜـــﻦ أ ﻀًـــﺎ ﻟﻠ ﻮاﻛـــﺐ ـــﺪروﺟ ـــﺎر واﻟﻬ ﻋﻠـــﻰﺷــ ﻞﺳـــﺤﺐ ﻣﻠﻴﺌـــﺔ ﺎﻟﻐ . ﺗﺤﺘـــﻮي أﻋﻤـــﺪة وأﻗﻮاس اﻟﻐﺎز ﻓﻲﻫﺬﻩ ﻣﻦ اﻟﻬ ﺪروﺟ اﻟﺼﻮرة ﻋﻠﻰ ﻧﻮﻋ ، ﻤﺜﻞ ـﺪروﺟ ﻨًﺎ ﻧﺸـﻄًﺎ ﻫ اﻟﻐﺎزاﻟﻮرد ﻳ ﻮن ﻋﺎدةً واﻟﺬ ﺑ ﺳﺎﺧﻨﺎً ﺤﻮاﻟﻲ ١٠٠٠٠ ـﺪروﺟ درﺟﺔ ﻣﺌﻮ ﺔ أو أﻛـ ، ﺑ ﻨﻤـﺎ ﻤﺜـﻞ اﻟﻐـﺎزاﻟ ﻘـﺎﻟﻲ اﻟﻬ ـ اﻟــ ـــﻒ اﻟﻜﺜ ﺠﺰ ــﻮن أﻛـــ ﺑـــﺮودة ﻋﻨــﺪ ﺣـــﻮاﻟﻲ ﻳ واﻟـــﺬ - ٢٠٠ ــﺔ أو أﻗـــﻞ درﺟـــﺔ ﻣﺌﻮ ـــﺎر اﻟﻤﻌـــﺰول واﻟﻐ . ] ـﺎ ﺳـﻲﺟـﻮﻧ ـﺔ ، أوﻟ ﻔ ـﺔ ، و ﺎﻟـﺔ اﻟﻔﻀـﺎء اﻟﻜﻨﺪ ﻧﺎﺳـﺎ ، و ﺎﻟـﺔ اﻟﻔﻀـﺎء اﻷوروﺑ ﺰ (UK ATC) ـﺪو د ، ﺟ ﻣﺎرﺷﻲ (ESTEC) ، ﻣﺎرﺟﺮ ﺖ ﻣ ﻜﺴ (USRA). ﻣﻌﺎ ﺔ اﻟﺼﻮر : أﻟ ﺴﺎ ﺎﻏﺎن (STScI) ، ﻧﻮﻻنﻫﺎﺑﻞ (USRA) ، Laura Lenkić (USRA) ، Laurie E.U Chu (NASA Ames)] ﻻ ﺗﺰال ﻧﺸﻄﺔ ﺑ ﺘﺸﻜﻴﻞ اﻟﻨﺠﻮم اﻟﺘـﻲ ﺗﺤـﺪث ﺑﻌﺪ ذﻟﻚ ﺗﺸﻜﻞ ا ﺠﺮات اﻟﺘـﻲ ﻧﺮاﻫـﺎ ﺣﻮﻟﻨـﺎ اﻟﻴﻮم " . ﻟﻦ ﻳﻜﻮن ﻟﺪى ﻣﺠﺮة ﰲ ﻓﱰة اﻟﻈﻬ ة اﻟﻜﻮﻧﻴـﺔ NGC 346 ﻣﺜـﻞ ﺳـﺤﺎﺑﺔ ﻣـﺎﺟﻼن اﻟﺼﻐﺮى . ﻗﺎﻟﺖ ﻣﺎرﻏﺮﻳـﺖ ﻣﻴﻜﺴـﻨﺮ ﻋﺎ ـﺔ اﻟﻔﻠﻚ ﰲ اﺗﺤﺎد أﺑﺤﺎث اﻟﻔﻀـﺎء ﺑﺎﻟﺠﺎﻣﻌـﺎت واﻟﺒﺎﺣﺜﺔ اﻟﺮﺋﻴﺴﻴﺔ ﰲ ﻓﺮﻳﻖ اﻟﺒﺤﺚ " ﺳﻴﻜﻮن ﻟﻬﺎ آﻻف ﻣﻨﺎﻃﻖ ﺗﺸﻜﻞ اﻟﻨﺠـﻮم ﻣﺜـﻞ ﻫـﺬه ا ﻨﻄﻘﺔ وﻟﻜﻦ ﺣﺘﻰ ﻟﻮ ﻛﺎﻧ ﺖ NGC 346 اﻵن ا ﻟﻌﻨﻘﻮد اﻟﻮﺣﻴﺪ اﻟﻀﺨﻢ اﻟﺬي ﻳﺸﻜﻞ اﻟﻨﺠـﻮم ﺑﻘﻮة ﰲ ﻣﺠﺮﺗﻪ ﺗ ﺎ ﻓﺈﻧﻬ ﻮﻓﺮ ﻟﻨﺎ ﻓﺮﺻﺔ ﻋﻈﻴﻤﺔ ﻻﺳﺘﻜﺸﺎف اﻟﻈﺮوف اﻟﺘـﻲ ﻛ ﺎﻧـﺖ ﻣﻮﺟـﻮدة وﻗﺖ اﻟﻈﻬ ة اﻟﻜﻮﻧﻴﺔ ﻓ . ﻤﻦ ﺧـﻼل ﻣﺮاﻗﺒـﺔ اﻟﻨﺠﻮم اﻷوﻟﻴﺔ اﻟﺘﻲ ﻻ ﺗ ﺰال ﰲ ﻃﻮر اﻟﺘﻜـﻮﻳﻦ ﻳﻤﻜﻦ ﻟﻠﺒﺎﺣﺜ ﻣﻌﺮﻓﺔ ﻣﺎ إذا ﻛﺎﻧـﺖ ﻋﻤﻠﻴـﺔ ﺗﺸﻜﻞ اﻟﻨﺠﻮم ﰲ ﺳﺤﺎﺑﺔ ﻣـﺎﺟﻼن اﻟﺼـﻐﺮى ﻣﺨﺘﻠﻔﺔ ﻋﻤﺎ ﻧﺮﺻﺪه ﰲ ﻣﺠﺮﺗﻨﺎ درب اﻟﺘﺒﺎﻧﺔ . رﻛـﺰت دراﺳـﺎت اﻷﺷـﻌﺔ ﺗﺤـﺖ اﻟﺤﻤ ـﺮاء اﻟﺴﺎﺑﻘﺔ ﻟـ NGC 346 ﻋﲆ ﻧﺠﻮم أوﻟﻴﺔ أﺛﻘﻞ ﻣﻦ ﺣﻮاﱄ ٥ إﱃ ٨ أﺿـﻌﺎف ﻛﺘﻠـﺔ اﻟﺸـﻤﺲ . ﺑﺤﺴﺐ أوﻟﻴﻔﻴﺎ ﺟﻮﻧﺰ ﻣﻦ ﻣﺮﻛﺰ اﻟﺘﻜﻨﻮﻟﻮﺟﻴﺎ اﻟﻔﻠﻜﻴﺔ ﰲ ا ﻤﻠﻜﺔ ا ﺘﺤـﺪة ﺑﺎﺣـﺚ ﻣﺸـﺎرك ــــ ﰲ اﻟﱪﻧ ـﺎﻣﺞ : ﺑﺎﺳـﺘﺨﺪام ﺗﻠﺴـﻜﻮب وﻳ ـﺐ ﻳﻤﻜﻨﻨﺎ ﻣﻌﺮﻓﺔ اﻟﻨﺠـﻮم اﻷوﻟﻴـﺔ ذات اﻟـﻮ زن اﻟﺨﻔﻴﻒ واﻟﺘﻲ ﻳﺒﻠﻎ ﺣﺠﻤﻬﺎ ﻋُﴩـ اﻟﺸـﻤﺲ ﻌﺮﻓﺔ ﻣﺎ إذا ﻛﺎﻧﺖ ﻋﻤﻠﻴـﺔ ﺗﻜﻮﻳﻨﻬـﺎ ﺗﺘـﺄﺛﺮ ﺑﺎ ﺤﺘﻮى ا ﻌﺪﻧﻲ ا ﻨﺨﻔﺾ " . ﺗﺘﺠﻤﻊ ا ﺎدة ﰲ ﻗﺮص ﺗـﺮاﻛﻢ ﻳﻐـﺬي اﻟـﻨﺠﻢ اﻷوﱄ ا ﺮﻛﺰي . اﻛﺘﺸﻒ اﻟﻔﻠﻜﻴﻮن ﻏﺎزًا ﺣـﻮل اﻟﻨﺠﻮم اﻷوﻟﻴﺔ داﺧﻞ NGC 346 ﻟﻜﻦ أرﺻـﺎد ﺗﻠﺴـﻜﻮب ﺑﺎ وﻳـﺐ ﻷﺷــﻌﺔ ﺗﺤــﺖ اﻟﺤﻤـﺮاء اﻟﻘﺮﻳﺒﺔ ﻫﻲ ا ﺮة اﻷوﱃ اﻟﺘﻲ اﻛﺘﺸـﻔﻮا ﻓﻴﻬـﺎ أﻳﻀًﺎ اﻟﻐﺒﺎر ﰲ ﻫﺬه اﻷﻗﺮاص . ﻗﺎل ﺟﻴﺪو دي ﻣﺎ رﳾ ﻣـﻦ وﻛﺎﻟـﺔ اﻟﻔﻀـﺎء اﻷوروﺑﻴـﺔ و ﺑﺎﺣـﺚ ﻣﺸـﺎرك " : ﻧﺤـﻦ ﻧـﺮى اﻟﻠﺒﻨﺎت اﻷﺳﺎﺳﻴﺔ ﻟﻴﺲ ﻓﻘﻂ ﻟﻠﻨﺠﻮم وﻟﻜـﻦ أﻳﻀً ﺎ ﻣﻦ ا ﺤﺘﻤﻞ أن ﺗﻜﻮن اﻟﻜﻮاﻛﺐ وﺑﻤﺎ أن ﺳﺤﺎﺑﺔ ﻣﺎﺟﻼن اﻟﺼﻐﺮى ﻟﻬﺎ ﺑﻴﺌﺔ ﻣﺸـﺎﺑﻬﺔ ﻟﻠﻤﺠـﺮات أﺛﻨـﺎء اﻟﻈﻬـ ة اﻟﻜﻮﻧﻴـﺔ ﻳﻤﺘﻠـﻚ اﻟﻔﺮﻳﻖ أﻳﻀًﺎ ﻣﻼﺣﻈﺎت ﻃﻴﻔﻴﺔ ﻣﻦ ﺗﻠﺴﻜﻮب وﻳﺐ واﻟﺘﻲ ﻳﻮاﺻﻠﻮن ﺗﺤﻠﻴﻠﻬﺎ . ﻳﺘﻮﻗﻊ أن ﺗﻮﻓﺮ ﻫـﺬه اﻟﺒﻴﺎﻧـ ﺎت رؤى ﺟﺪﻳـﺪة ﺣﻮل ا ﺎدة اﻟﺘﻲ ﺗﱰاﻛﻢ ﻋﲆ اﻟﻨﺠـﻮم اﻷوﻟﻴـﺔ اﻟﻔﺮدﻳﺔ و اﻟﺒﻴﺌﺔ ا ﺤﻴﻄﺔ ﺑﺎﻟﻨﺠﻢ اﻷوﱄ . ﺎﻧﺖ ﻣﺎرس أﺑﺮﻳﻞ 2023