Free Astronomy Magazine March-April 2024 ARABIC VERSION

A Water vapour in small exoplanet’s atmosphere by NASA/ESA − Bethany Downer stronomers using the NASA/ ESA Hubble Space Telescope observed the smallest exo- planet where water vapour has been detected in its atmosphere. At only approximately twice Earth’s di- ameter, the planet GJ 9827d could be an example of potential planets with water-rich atmospheres else- where in our galaxy. “This would be the first time that we can directly show through an atmospheric de- tection that these planets with water-rich atmospheres can actually exist around other stars,” said team member Björn Benneke of the Uni- versité de Montréal. “This is an im- portant step toward determining the prevalence and diversity of at- mospheres on rocky planets.” However, it remains too early to tell whether Hubble spectroscopically measured a small amount of water vapour in a puffy hydrogen-rich at- mosphere, or if the planet’s atmos- phere is mostly made of water, left behind after a primaeval hydrogen/ helium atmosphere evapourated un- der stellar radiation. “Our observing programme was de- signed specifically with the goal of not only detecting the molecules in the planet’s atmosphere, but of ac- tually looking specifically for water vapour. Either result would be ex- citing, whether water vapour is dominant or just a tiny species in a hydrogen-dominant atmosphere,” said the science paper’s lead author, Pierre-Alexis Roy of the Université de Montréal. “Until now, we had not been able to directly detect the atmosphere of such a small planet. And we’re slowly getting into this regime now,” added Benneke. “At 46 " ﺑﺨﺎراﻟﻤﺎء " ﻓﻲاﻟﻐﻼف ـاﻟ ﺠﻮيﻟ ﻮﻛﺐ ﻧ ﻤﻲ ﺻﻐ : ﻘﻠﻢ ﺑ ﺜﺎﻧﻲداوﻧﺮ - و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ - ﻣﺎﺭﺱ ﺃﺑﺮﻳﻞ 2 0 2 4 رﺻـﺪ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﺑﺎﺳـﺘﺨﺪام ﺗﻠﺴـﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳﺎ ووﻛﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑﻴﺔ وﺟﻮد ﺑﺨﺎر ا ﺎء ﰲ اﻟﻐﻼف اﻟﺠﻮي ﻷ ﺻﻐﺮ ﻛﻮﻛﺐ . ﻧﺠﻤﻲ اﻟﻜﻮﻛـﺐ GJ 9827d اﻟﺬ ي ﻳﺒﻠﻎ ﻗﻄﺮه ﺿﻌﻒ ﻗﻄﺮ اﻷرض ﺗﻘﺮﻳﺒﺎ ﻳﻤﻜﻦ أن ﻳﻜﻮن ﻣﺜﺎﻻً ﻟﻠﻜﻮاﻛﺐ ا ﺤﺘﻤﻠﺔ ذات اﻷﺟـﻮاء اﻟﻐﻨﻴـﺔ ﺑﺎ ﻴـﺎه ﰲ ﻣﻜـﺎن آﺧـﺮ ﰲ . ﻣﺠﺮﺗﻨﺎ ﻗﺎل ﺑﻴﻮرن ﺑﻴﻨﻴﻜﻲ ﻋﻀﻮ اﻟﻔﺮﻳـﻖ ﻣﻦ ﺟﺎﻣﻌﺔ ﻣﻮﻧﱰﻳﺎل " : ﺳﺘﻜﻮن ﻫـﺬه ﻫـﻲ ا ﺮة اﻷوﱃ اﻟﺘﻲ ﻳﻤﻜﻨﻨﺎ ﻓﻴﻬﺎ أن ﻧﻈﻬﺮ ﺑﺸﻜﻞ ﻣﺒﺎﴍﻣﻦ ﺧﻼل اﻛﺘﺸﺎف اﻟﻐﻼف اﻟﺠﻮي أن ﻫﺬه اﻟﻜﻮاﻛﺐ ذات اﻷﺟـﻮاء اﻟﻐﻨﻴـﺔ ﺑﺎ ﻴـﺎه ــــ ﻳﻤﻜﻦ أن ﺗﻮﺟﺪ ﺑﺎﻟﻔﻌﻞ ﺣﻮل ﻧﺠﻮم أﺧﺮى ." " ﻫﺬه ﺧﻄـﻮة ﻣﻬﻤـﺔ ﻧﺤـﻮ ﺗﺤﺪﻳـﺪ ﻣـﺪى اﻧﺘﺸـﺎر وﺗﻨــ ﻮع اﻷﺟــﻮاء ﻋ ـﲆ اﻟﻜﻮاﻛــﺐ اﻟﺼﺨﺮﻳﺔ وﻣﻊ ذﻟـﻚ ﻻ ﻳـﺰال ﻣـﻦ اﻟﺴـﺎﺑﻖ ﻷواﻧﻪ ﻣﻌﺮﻓﺔ ﻣﺎ إذا ﻛﺎن ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ ﻗﺪ ﻗﺎم ﺑﻘﻴﺎس ﻛﻤﻴﺔ ﺻﻐ ة ﻣـﻦ ﺑﺨـﺎر ا ـﺎء ﺑﺎﺳﺘﺨﺪام اﻟﺘﺤﻠﻴﻞ اﻟﻄﻴﻔﻲ ﰲ ﻏﻼف ﺟـﻮي ﻣﻨﺘﻔﺦ ﻏﻨﻲ ﺑﺎﻟﻬﻴﺪروﺟ ، أو ﻣـ ﺎ إذا ﻛـﺎن اﻟﻐﻼف اﻟﺠﻮي ﻟﻠﻜﻮﻛﺐ ﻳﺘﻜﻮن ﰲ ﻣﻌﻈﻤـﻪ ﻣﻦ ا ﺎء اﻟﺬي ﺗﺮﻛﻪ ﺑﻌﺪ ﺗﺒﺨﺮ اﻟﻐﻼف اﻟﺠﻮي ﻟﻠﻬﻴــﺪروﺟ اﻟﻬﻴﻠﻴــ / ﻮم اﻟﺒــﺪاﺋﻲ ﺗﺤــﺖ اﻹﺷﻌﺎع اﻟﻨﺠﻤﻲ . " ﻟﻘﺪ ﺗﻢ ﺗﺼﻤﻴﻢ ﺑﺮﻧﺎﻣﺞ ا ﺮاﻗﺒﺔ اﻟﺨﺎص ﺑﻨﺎ ﺧﺼﻴﺼًـﺎ ﻟ ـﻴﺲ ﻓﻘـﻂ ﺑﻬ ـﺪف اﻛﺘﺸـﺎف اﻟﺠﺰﻳﺌ ـﺎت ا ﻮﺟــﻮدة ﰲ اﻟﻐ ـﻼف اﻟﺠــﻮي ﻟﻠﻜﻮﻛﺐ، وﻟﻜﻦ أﻳﻀًﺎ ا ﻟﺒﺤﺚ ﻓﻌﻠﻴًﺎ ﻋﻦ ﺑﺨﺎر ا ﺎء ﻋﲆ وﺟﻪ اﻟﺘﺤﺪﻳﺪ . ﻗﺎل ا ﺆﻟﻒ اﻟﺮﺋﻴﴘ ﻟﻠﻮرﻗﺔ اﻟﻌﻠﻤﻴـﺔ، ﺑﻴـ أﻟﻜﺴ ـﻴﺲ روي ﻣ ـﻦ ﺟﺎﻣﻌ ـﺔ ﻣﻮﻧﱰﻳ ـﺎل : " ﺳﺘﻜﻮن أي ﻣﻦ اﻟﻨﺘﻴﺠﺘـ ﻣﺜـ ة، ﺳـﻮاء ﻛﺎن ﺑﺨﺎر ا ﺎء ﻫﻮ اﻟﺴـﺎﺋﺪ أو ﻣﺠـﺮد ﻧـﻮع ﺻﻐ ﰲ ﺟﻮ ﻳﻬﻴﻤﻦ ﻋﻠﻴﻪ اﻟﻬﻴﺪروﺟ ." " ﺣﺘﻰ اﻵن ﻟﻢ ﻧﺘﻤﻜﻦ ﻣﻦ اﻛﺘﺸﺎف اﻟﻐـﻼف اﻟﺠﻮي ﻟﻜﻮﻛﺐ ﺻﻐ ﻛﻬﺬا ﺑﺸﻜﻞ ﻣﺒﺎﴍ . أﺿﺎف ﺑﻴﻨﻴﻜﻲ " : إﻧﻨﺎ ﻧـﺪ ﺧﻞ ﺑـﺒﻂء ﰲ ﻫـﺬا اﻟﻨﻈﺎم اﻵن ."