Free Astronomy Magazine May-June 2023 ARABIC VERSION

MAY-JUNE 2023 A white dwarf mass meas-   First direct mass measurement of a lone white dwarf by NASA/ESA Bethany Downer stronomers us- ing the NASA/ ESA Hubble Space Telescope have for the first time directly measured the mass of a single, isolated white dwarf star – the surviv- ing core of a burned- out sunlike star. Researchers found that the white dwarf is 56 percent of the mass of our Sun. This agrees with earlier theoretical predictions of its mass and corroborates cur- rent theories of how white dwarfs evolve as the end product of a typical star’s evolution. The unique observation yields insights into the- ories of the structure and composition of white dwarfs. Until now, previous urements have been gleaned from observing white dwarfs in binary star systems. By watch- ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ ٢٦ أ ــــــــــﺎسﻣ ﺎﺷــــــــــﺮﻟﻜﺘﻠــــــــــﺔ ول ﻗ ﻗﺰم أﺑ ﺾوﺣ ﺪ : ﻘﻠﻢ ﺑ ﺜﺎﻧﻲ داوﻧﺮ و ﺎﻟ / ﺔ ﻧﺎﺳﺎ و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﺑﺎﺳﺘﺨﺪام ﺗﻠ ﺴــﻜﻮب ﻫﺎﺑــﻞ اﻟﻔﻀــﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ و ﻧﺎﺳـﺎ وﻛﺎﻟـﺔ اﻟﻔﻀﺎء اﻷوروﺑﻴﺔ ﻟﻠﻤﺮة اﻷوﱃ ﺑﻘﻴﺎس ﻛﺘﻠﺔ ﻧﺠﻢ ﻗﺰم أﺑـﻴﺾ ﻣﻨﻔـﺮد وﻫـﻮ اﻟﻨـﻮاة اﻟﺒﺎﻗﻴـﺔ ﻟﻨﺠﻢ ﻣﺤﱰق ﺷﺒﻴﻪ ﺑﺎﻟﺸﻤﺲ . ﻟﻘﺪ وﺟﺪ اﻟﺒـﺎﺣﺜﻮن أن اﻟﻘـﺰم اﻷﺑﻴﺾ ﻳﻤﺜﻞ ٥٦ ﺑﺎ ﺎﺋـﺔ ﻣـﻦ ﻛﺘﻠﺔ اﻟﺸﻤﺲ . ﻳﺘﻔ ـﻖ ﻫ ـﺬا ﻣ ـﻊ اﻟﺘﻮﻗﻌ ـﺎت اﻟﻨﻈﺮﻳﺔ اﻟﺴﺎﺑﻘﺔ ﻋـﻦ ﻛﺘﻠﺘـﻪ وﻳﺆﻳﺪ اﻟﻨﻈﺮﻳﺎت اﻟﺤﺎﻟﻴﺔ ﺣﻮل ﻛﻴﻔﻴﺔ ﺗﻄﻮر اﻷﻗﺰام اﻟﺒﻴﻀـﺎء ﻛﻤﻨﺘﺞ ﻧﻬـﺎﺋﻲ ﻟﺘﻄـﻮر ﻧﺠـﻢ ﻧﻤﻮذﺟﻲ . ﺗﻨﺘﺞ اﻷرﺻـﺎد اﻟﻔﺮﻳـﺪة رؤى ﺛﺎﻗﺒﺔ ﻟﻨﻈﺮﻳﺎت ﺑﻨﻴﺔ وﺗﻜـﻮﻳﻦ اﻷﻗﺰام اﻟﺒﻴﻀﺎء . ﻟﻘــﺪ ﺣﺼــﻞ اﻟﻌﻠﻤــﺎء ﻋــﲆ ﻗﻴﺎﺳﺎت ﻛﺘ اﻷ ﻠﺔ ﻗﺰام اﻟﺒﻴﻀﺎء اﻟﺴﺎﺑﻘﺔ ﻣﻦ ﻣﺮاﻗﺒـﺔ اﻷﻗـﺰام اﻟﺒﻴﻀـﺎء ﰲ أﻧﻈﻤ ـﺔ اﻟﻨﺠ ـﻮم اﻟﺜﻨﺎﺋﻴﺔ . ـﻢ ﻗـﺰم أﺑـ ﺾ ﺴـﻤﻰ ـﺎسﻛﺘﻠـﺔ ﻧ اﺳـﺘﺨﺪم ﺗﻠﺴـ ﻮب ﻫﺎﺑـﻞ اﻟﻌﺪﺳـﺔ اﻟﺪﻗ ﻘـﺔ ﻟﻘ LAWD 37. إﻧـﮫ اﻟـ ﻨ ﻢ اﻟ ﻤﺤـ ق ﻓﻲ ﺻﻮرة ﻫﺎﺑﻞ ﻫـﺬﻩ . ﻋﻠـﻰ اﻟـﺮﻏﻢ ﻣـﻦ أن ﻓـﺮن اﻻﻧـﺪﻣﺎج اﻟﻨـﻮوي اﻟـ ـ ـﮫ ﻗـﺪ ﺗﻮﻗـﻒ ﺨﺎص إﻻ أن اﻟـ ﺤـ ﺮارة اﻟﻤﺤﺒﻮﺳـﺔ ﺗﺘﺼﺎﻋﺪ ﻋﻠﻰ اﻟﺴـﻄﺢ ﻋﻨـﺪ ﺣـﻮاﻟﻲ ١٠٠,٠٠٠ ـﺔ درﺟـﺔ ﻣﺌﻮ ـ ﻣﻤـﺎ ﺘﺴـ ﺐ ﻓـﻲ ﺗـﻮﻫﺞ ﻘﺎ ﺎ اﻟﻨﺠـﻮم ﺸـﺪة . اﻟﻘـﺰم اﻷﺑـ ﺾ ﻟﮫ ﻃﻔﺮة ﻷﻧﮫﺳﺎﻃﻊ ﻟﺪرﺟﺔ أن اﻟﻀﻮء " ﺘﺸﻮﻩ ﻓﻲ " ﺣﺴﺎﺳﺎتﺳﻲﺳﻲد ﺑ ﺎﻣ ا ﻫﺎﺑﻞ . - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2023 ﻗﺎم