Free Astronomy Magazine September-October 2022 ARABIC VERSION

Triangulum galaxies. All four are within 3 million light-years of Earth. In the images, red indicates hydro- gen gas, the most common element in the universe. The image of the Large Magellanic Cloud shows a red tail coming off the bottom left of the galaxy that was likely created when it collided with the Small Magellanic Cloud about 100 million years ago. Bub- bles of empty space indicate regions where stars have recently formed, because intense winds from the newborn stars blow away the sur- rounding dust and gas. The green light around the edges of those bubbles indicates the presence of cold dust that has piled up as a re- sult of those winds. Warmer dust, shown in blue, indicates where stars are forming or other processes have heated the dust. Many heavy elements in nature – like carbon, oxygen, and iron – can get stuck to dust grains, and the presence of different elements changes the way dust absorbs starlight. This in turn affects the view astronomers get of events like star formation. In the densest dust clouds, almost all the heavy ele- ments can get locked up in dust grains, which increases the dust-to- gas ratio. But in less dense regions, the destructive radiation from new- born stars or shockwaves from ex- ploding stars will smash the dust grains and return some of those locked-up heavy elements back into the gas, changing the ratio once again. Scientists who study interstel- lar space and star formation want to better understand this ongoing cycle. The Herschel images show that the dust-to-gas ratio can vary within a single galaxy by up to a fac- tor of 20, far more than previously estimated. “These improved Herschel images show us that the dust ‘ecosystems’ in these galaxies are very dynamic,” said Christopher Clark, an as- tronomer at the Space Science Tele- scope Institute in Baltimore, Mary- land, who led the work to create the new images. These results were featured in a press conference at the summer meeting of the Ameri- can Astronomical Society.      ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ٤٩ اﻷرﺑﻌﺔ ﻛﻠﻬﺎ ﺗﻘﻊ ﻋﲆ ﺑﻌﺪ ٣ ﻣﻼﻳـ ﺳـﻨﺔ ﺿﻮﺋﻴﺔ ﻣﻦ اﻷرض . ﰲ اﻟﺼﻮر ، ﻳﺸ ا ﻟﻠﻮن اﻷﺣﻤﺮ إﱃ ﻏـﺎز ا ﻟﻬﻴـﺪروﺟ اﻟـﺬي ﻳﻌﺘـﱪ اﻟﻌﻨﴫ اﻷﻛﺜـﺮ ﺷـﻴﻮﻋًﺎ ﰲ اﻟﻜـﻮن . ﺗُﻈﻬـﺮ ﺻﻮرة ﺳﺤﺎﺑﺔ ﻣﺎﺟﻼن اﻟﻜﺒ ة ذﻳـﻼً أﺣﻤـﺮ ﻗﺎدﻣًﺎ ﻣﻦ أﺳﻔﻞ ﻳﺴﺎر ا ﺠـﺮة واﻟـﺬي ﻣـﻦ ا ﺤﺘﻤﻞ أن ﻳﻜﻮن ﻗـﺪ ﺗـﻢ إﻧﺸـﺎؤه ﻋﻨـﺪﻣﺎ اﺻﻄﺪم ﺑﺴﺤﺎﺑﺔ ﻣـﺎﺟﻼن اﻟﺼـﻐ ة ﻗﺒـﻞ ﺣﻮاﱄ ١٠٠ ﻣﻠﻴـﻮن ﺳـﻨﺔ . ﺗﺸـ ﻓﻘﺎﻋـﺎت اﻟﻔﻀﺎء اﻟﻔﺎرغ إﱃ ا ﻨﺎﻃﻖ اﻟﺘﻲ ﺗﻜﻮﻧﺖ ﻓﻴﻬﺎ اﻟﻨﺠﻮم ﻣﺆﺧﺮًا ، وذﻟﻚ ﻷن اﻟﺮﻳـﺎح اﻟﺸـﺪﻳﺪة اﻟﻘﺎدﻣﺔ ﻣﻦ اﻟﻨﺠﻮم ﺣﺪﻳﺜﺔ اﻟـﻮﻻدة ﺗﻨﻔـﺚ اﻟﻐﺒﺎر واﻟﻐﺎز ا ﺤﻴﻄ ﺑﻬﺎ . ﻳﺸـ اﻟﻀـﻮء اﻷﺧﴬ ﺣـﻮل ﺣـﻮاف ﺗﻠـﻚ اﻟﻔﻘﺎﻋـﺎت إﱃ وﺟﻮد ﻏﺒﺎر ﺑﺎرد ﺗﺮاﻛﻢ ﻧﺘﻴﺠﺔ ﻟﺘﻠـﻚ اﻟﺮﻳـﺎح ﻳﺸ اﻟﻐﺒﺎر ــــــــــــــــ اﻷﻛﺜـﺮ دﻓﺌًـﺎ ، ا ﻮﺿـ ﺢ ﺑـﺎﻟﻠﻮن اﻷزرق ، إﱃ ﻣﻜﺎن ﺗﻜﻮن اﻟﻨﺠﻮم أو ﺣﻴﺚ أدت اﻟﻌﻤﻠﻴﺎت اﻷﺧﺮى إﱃ ﺗﺴﺨ اﻟﻐﺒﺎر . ﻳﻤﻜﻦ أن ﺗﺘﻌﺜـﺮ اﻟﻌﺪﻳﺪ ﻣﻦ اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ ﰲ اﻟﻄﺒﻴﻌﺔ ﻣﺜﻞ اﻟﻜﺮﺑﻮن واﻷﻛﺴـﺠ واﻟﺤﺪﻳـﺪ ﰲ ﺣﺒﻴﺒـﺎت اﻟﻐﺒﺎر ، ﻛﻤﺎ أن وﺟﻮد ﻋﻨﺎﴏ ﻣﺨﺘﻠﻔﺔ ﻳﻐ اﻟﻄﺮﻳﻘﺔ اﻟﺘـﻲ ﻳﻤـﺘﺺ ﺑﻬـﺎ اﻟﻐﺒـﺎر ﺿـﻮء اﻟﻨﺠﻮم و . ﻫﺬا ﺑﺪوره ﻳﺆﺛﺮ ﻋﲆ ﻧﻈﺮة ﻋﻠﻤـﺎء اﻟﻔﻠﻚ ﻷﺣﺪاث ﻣﺜﻞ ﺗﺸﻜﻞ اﻟﻨﺠـﻮم . ﰲ أﻛﺜـﺮ ﺳﺤﺐ اﻟﻐﺒﺎر ﻛﺜﺎﻓﺔ ، ﻳﻤﻜﻦ أن ﺗﻨﻐﻠﻖ ﺟﻤﻴﻊ اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ ﺗﻘﺮﻳﺒًﺎ ﰲ ﺣﺒﻴﺒـﺎت اﻟﻐﺒـﺎر ﻣﻤﺎ ﻳﺰﻳﺪ ﻣﻦ ﻧﺴﺒﺔ اﻟﻐﺒﺎر إﱃ اﻟﻐﺎز . وﻟﻜﻦ ﰲ ا ﻨﺎﻃﻖ اﻷﻗﻞ ﻛﺜﺎﻓﺔ ، ﻓﺈن اﻹﺷـﻌﺎع ا ـﺪﻣﺮ ﻣـﻦ اﻟﻨﺠــﻮم ا ﻮﻟـﻮدة ﺣـﺪﻳﺜً ﺎ أو ﻣﻮﺟــﺎت اﻟﺼـﺪﻣﺔ ﻣ ـﻦ اﻟﻨﺠـﻮم ا ﺘﻔﺠ ـﺮة ﺳـﻮف ــــــــــــــــــ ﻳﺴﺤﻖ ﺣﺒﻴﺒﺎت اﻟﻐﺒﺎر وﻳﻌﻴـﺪ ﺑﻌـﺾ ﺗﻠـﻚ اﻟﻌﻨﺎﴏ اﻟﺜﻘﻴﻠﺔ ا ﺤﺒﻮﺳﺔ إﱃ اﻟﻐـﺎز ، ﻣﻤـﺎ ﻳﺆدي إﱃ ﺗﻐﻴ اﻟﻨﺴـﺒﺔ ﻣـﺮة أﺧـﺮى . ﻳﺮﻳـﺪ اﻟﻌﻠﻤﺎء اﻟﺬﻳﻦ ﻳﺪرﺳﻮن اﻟﻔﻀﺎء ﺑ اﻟﻨﺠﻮم وﺗﺸﻜﻴﻞ اﻟﻨﺠﻮم ﻓﻬﻢ ﻫﺬه اﻟﺪورة ا ﺴﺘﻤﺮة ﺑﺸﻜﻞ أﻓﻀ إن. ﻞ اﻟﺼﻮر ا ﻠﺘﻘﻄﺔ ﺑﻮاﺳﻄﺔ ﻣﺮﺻﺪ ﻫ ﺷﻞ ﺗُﻈﻬﺮ أن ﻧﺴـﺒﺔ اﻟﻐﺒـﺎر إﱃ اﻟﻐﺎز ﻳﻤﻜﻦ أن ﺗﺨﺘﻠﻒ داﺧﻞ ﻣﺠﺮة واﺣـﺪة ﺑﻤﺎ ﻳﺼﻞ إﱃ ٢٠ ﺿﻌﻔًﺎ وﻫﻮ أﻛﺜﺮ ﺑﻜﺜ ﻣﻤﺎ ﻛﺎن ﻳُﻘﺪر ﺳﺎﺑﻘًﺎ ﺑﺤﺴﺐ ﻛﺮﻳﺴﺘﻮﻓﺮ ﻛﻼرك ، ﻋـﺎﻟﻢ اﻟﻔﻠـﻚ ﰲ ﻣﻌﻬـﺪ ﻋﻠـﻮم اﻟﻔﻀـﺎء ﰲ ﺑﺎﻟﺘﻴﻤﻮر ، ﻣﺎرﻳﻼﻧﺪ ، اﻟﺬي ﻗﺎد اﻟﻌﻤـﻞ ﻋـﲆ إﻧﺸﺎء اﻟﺼﻮر . ﺗﻢ ﻋـﺮض ﻫـﺬه اﻟﻨﺘـﺎﺋﺞ ﰲ ﻣــﺆﺗﻤﺮ ﺻــﺤﻔﻲ ﰲ اﻻﺟﺘﻤــﺎع اﻟﺼــﻴﻔﻲ ﻟﻠﺠﻤﻌﻴﺔ اﻟﻔﻠﻜﻴﺔ اﻷﻣﺮﻳﻜﻴﺔ . ﺳﺒﺘﻤ أﻛﺘﻮﺑﺮ 2022 ﻣﺠـﺮة اﻟﻤﺜﻠـﺚ ، أو ﻣ ﺴـﻴ ﮫ 33 ـﺪة وأﻃـﻮال ﻣﻮﺟـﺎت اﻟﺮادﻳـﻮ ، ﺗﻈﻬـﺮﻫﻨـﺎ ﻓـﻲ اﻷﺷـﻌﺔ ﺗﺤـﺖ ا ﻤـﺮاء اﻟ ﻌ . ـﺪرو ﺗـﻢﺳـﺤﺐ ﻌـﺾﻏـﺎز اﻟﻬ ) ﺟ اﻷ ﻤـﺮ ( ﻣـﻦﺣﺎﻓـﺔ اﻧﺪﻣﺠﺖ ﻣﻊ اﻟﻤﺠﺮات ، وﺗﻤﺰق اﻟ ﻌﺾاﻵﺧﺮ ﻌ ﺪًا ﻋﻦ اﻟﻤﺠﺮات اﻟ ﻗﺮص اﻟﻤﺠﺮة ﻧﺤﻮ اﻟﻔﻀﺎء ﺑ ـﺪًا ﻓـﻲ اﻟﻤﺎﺿـﻲ ﻣﺠﺮة اﻟﻤﺜﻠﺚ ﻌ . ـﻮن اﻟﺼـﻮرة ﻣـﻦ ﺑ ﺎﻧـﺎت ﺗﺘ ﻣﻦ ﻌﺜﺔ ﻫ ﺷﻞ اﻟﺘﺎ ﻌﺔ ﻟﻮ ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ ﻣﻊ اﺳﺘ ﻤﺎﻟﻬﺎ ﺑﺒ ﺎﻧﺎت ﻣـﻦ ﻣﺮﺻـﺪ ﻼﻧـﻚ اﻟﺘـﺎﺑﻊ ﻟﻮ ﺎﻟـﺔ ﻣـﻦ ﻌﺜـﺎت ﻧﺎﺳـﺎ ـﺔ وﻣﻬﻤﺘـ اﻟﻔﻀـﺎء اﻷوروﺑ : اﻟﻤﺴـﺢ ﺎﻷﺷﻌﺔ ﺗﺤﺖ ا ﻤﺮاء وﻣﺴﺘﻜﺸﻒ ا ﻠﻔ ﺔ اﻟ ﻮﻧ ﺔ ، و اﻟﻤﺼﻔﻮﻓﺔ اﻟﻜﺒ ة ﺟﺪًا ﺗﻠﺴ ﻮب ﻏﺮ ﻦ ﺎﻧﻚ وﺗﻠﺴ ﻮب IRAM اﻟﺮادﻳﻮ .ي [ESA,NASA, NASA-JPL, Caltech, Christopher Clark (STScI), E. Koch (University of Alberta), C. Druard (University of Bordeaux)]