Free Astronomy Magazine July-August 2024 ARABIC VERSION

he graph compares data collected by NIRCam (orange dots) and MIRI (purple dots) to two different models. Model A, in red, shows what the emis- sion spectrum of 55 Cancri e should look like if it has an atmosphere made of vaporized rock. Model B, in blue, shows what the emission spectrum should look like if the planet has a volatile-rich atmosphere outgassed from a magma ocean that has a similar volatile content as Earth’s mantle. Both MIRI and NIRCam data are consistent with the volatile-rich model. [Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI). Science: Renyu Hu (NASA-JPL), Aaron Bello-Arufe (NASA-JPL), Michael Zhang (University of Chicago), Mantas Zilinskas (SRON)] By subtracting the brightness during the secondary eclipse, when the planet is behind the star (starlight only), from the brightness when the planet is right beside the star (light from the star and planet combined), the team was able to calculate the amount of various wavelengths of infrared light coming from the day- side of the planet. This method, known as secondary eclipse spectroscopy, is similar to that used by other research teams to search for atmospheres on other rocky exoplanets, like TRAPPIST-1 b. The first indication that 55 Cancri e could have a substantial atmos- phere came from temperature mea- surements based on its thermal emission, or heat energy given off in the form of infrared light. If the planet is covered in dark molten rock with a thin veil of vaporized rock or no atmosphere at all, the dayside should be around 4,000 de- grees Fahrenheit (~2,200 degrees Celsius). “Instead, the MIRI data showed a relatively low temperature of about 2,800 degrees Fahrenheit [~1540 de- grees Celsius] ,” said Hu. “ This is a very strong indication that energy is being distributed from the day- side to the nightside, most likely by a volatile-rich atmosphere.” While currents of lava can carry some heat around to the nightside, they can- not move it efficiently enough to ex- plain the cooling effect. When the team looked at the NIR- Cam data, they saw patterns consis- tent with a volatile-rich atmosphere. “We see evidence of a dip in the spectrum between 4 and 5 microns — less of this light is reaching the telescope,” explained co-author Aaron Bello-Arufe, also from NASA JPL. “This suggests the presence of an atmosphere containing carbon monoxide or carbon dioxide, which absorb these wavelengths of light.” A planet with no atmosphere or an atmosphere consisting only of va- porized rock would not have this specific spectral feature. “We’ve spent the last ten years mod- elling different scenarios, trying to imagine what this world might look like,” said co-author Yamila Miguel from the Leiden Observatory and the Netherlands Institute for Space Research (SRON). “Finally getting some confirmation of our work is priceless!” The team thinks that the gases blan- keting 55 Cancri e would be bub- bling out from the interior, rather than being present ever since the planet formed. “The primary atmos- phere would be long gone because of the high temperature and intense radiation from the star,” said Bello- Arufe. “This would be a secondary atmosphere that is continuously re- plenished by the magma ocean. Magma is not just crystals and liquid rock; there’s a lot of dissolved gas in it, too.” While 55 Cancri e is far too hot to be habitable, researchers think it could provide a unique window for study- ing interactions between atmos- pheres, surfaces, and interiors of rocky planets, and perhaps provide insights into the early conditions of Earth, Venus, and Mars, which are thought to have been covered in magma oceans far in the past. “Ulti- mately, we want to understand what conditions make it possible for a rocky planet to sustain a gas-rich atmosphere: a key ingredient for a habitable planet,” said Hu.      ﻘـﺎرن ﺗــ ـﺎﻧﻲ اﻟﺒ ﺎﻧــﺎت اﻟــ اﻟﺮﺳــﻢ اﻟﺒ ﻢ ﻤﻌﻬـﺎ ﺑﻮاﺳـﻄﺔ ــﺎم ــﺎﻣ ا ﻧ ) ــﺔ اﻟﻨﻘــﺎط اﻟ ﻘﺎﻟ ( ــﺎﻣ ا ﻣــ ي و ) ـﺔ اﻟﻨﻘــﺎط اﻷرﺟﻮاﻧ ( ﻣﺨﺘﻠﻔــ ﻨﻤــﻮذﺟ . ُﻈﻬـﺮ اﻟﻨﻤــﻮذج A ــﺎﻟﻠﻮن اﻷ ﻤـﺮ ــﻒ اﻻﻧ ﻌــﺎث ﻟﻠ ﻮﻛــﺐ ــﺪو ﻃ ــﻒ ﻨ ﻐــﻲ أن ﻳ ﻛ )55 ــﺎﻧﻜﺮي إي ( ــﺎن ﻟــﮫ ﻏــﻼفﺟــﻮي إذا ــﻮن ﺘ ﻣــﻦ اﻟﺼـﺨﻮر اﻟﻤﺘﺒﺨــﺮة . ُﻈﻬـﺮ اﻟﻨﻤــﻮذج B ــﺎﻟﻠﻮن اﻷ زرق ــﻒ ﻛ ﻳﺤﺘـﻮيﻋﻠـﻰﻣﺤ ـﺎﻟﻤﻮاد اﻟﻤﺘﻄـﺎﻳﺮة اﻟﻤﻨ ﻌﺜـﺔ ﻣـﻦ ﻣﺤـ ﻂ اﻟﺼـﻬﺎرة اﻟـﺬ ﻨ ﻐﻲ أن ﻳ ﺪو ﻃ ﻒ اﻻﻧ ﻌﺎث إذا ﺎن اﻟ ﻮﻛﺐ ﻳﺤﺘﻮيﻋﻠﻰﻏﻼفﺟﻮيﻏ ﺘـﻮىﻣﺘﻄـﺎﻳﺮﻣﻤﺎﺛـﻞ ﻟﻐﻄﺎء اﻷرض . ﺗﺘﻮاﻓﻖ ﺑ ﺎﻧﺎت ﺎﻣ ا ﻣ يو ﺎﻣ ا ﻧ ﺎم ﺎﻟﻤﻮاد اﻟﻤﺘﻄﺎﻳﺮة ﻣﻊ اﻟﻨﻤﻮذج اﻟﻐ . - ﻳﻮﻟﻴﻮ ﺃﻏﺴﻄﺲ 2 0 2 4 ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ ن أ ﺗﻠﺴﻜﻮب وﻳﺐ ﻻ ﻳﺴﺘﻄﻴﻊ اﻟﺘﻘــﺎط ﺻــﻮرة ﻣﺒــﺎﴍة ﻟ ﻠﻜﻮﻛــﺐ )55 ﻛﺎﻧﻜﺮي إي ( إﻻ أﻧﻪ ﻳﻤﻜﻨﻪ ﻗﻴﺎس اﻟﺘﻐـ ات اﻟﻄﻔﻴﻔﺔ ﰲ اﻟﻀﻮء اﻟﺼﺎدر ﻣﻦ اﻟﻨﻈﺎم أﺛﻨﺎء دوران اﻟﻜﻮﻛﺐ ﺣﻮل اﻟﻨﺠﻢ ﻓ ﻤﻦ ﺧﻼل ﻃﺮح اﻟﺴﻄﻮع أﺛﻨـﺎء اﻟﻜﺴـﻮف اﻟﺜـﺎﻧﻮي ﻋﻨـﺪﻣﺎ ﻳﻜﻮن اﻟﻜﻮﻛﺐ ﺧﻠﻒ اﻟﻨﺠﻢ ) ﺠـﻮم ﺿـﻮء اﻟﻨ ( ﻓﻘﻂ ﻣﻦ اﻟﺴﻄﻮع ﻋﻨﺪﻣﺎ ﻳﻜﻮن اﻟﻜﻮﻛـﺐ ﺑﺠﻮار اﻟﻨﺠﻢ ﻣﺒ ﺎﴍة ) اﻟﻀـﻮء ﻣـﻦ اﻟـﻨﺠﻢ واﻟﻜﻮﻛﺐ ﻣﻌ (ﺎً ﺗﻤﻜﻦ اﻟﻔﺮﻳﻖ ﻣـﻦ ﺣﺴـﺎب ﻣﻘﺪار اﻟﺴﻄﻮع ﺑﺄﻃﻮال ﻣﻮﺟﻴـﺔ ﻣﺨﺘﻠﻔـﺔ ﻣﻦ اﻷﺷﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء اﻟﻘﺎدﻣـﺔ ﻣـﻦ اﻟﺠﺎﻧـﺐ اﻟﻨﻬـﺎري ﻟﻠﻜﻮﻛـﺐ . ﺗﺸـﺒﻪ ﻫــﺬه اﻟﻄﺮﻳﻘﺔ ا ﻌﺮوﻓﺔ ﺑﺎﺳﻢ اﻟﺘﺤﻠﻴـﻞ اﻟﻄﻴﻔـﻲ ﻟﻠﻜﺴﻮف اﻟﺜﺎﻧﻮي ﺗﻠﻚ ا ﺴﺘﺨﺪﻣﺔ ﻣﻦ ﻗﺒـﻞ ﻓﺮق ﺑﺤﺜﻴﺔ أﺧﺮى ﻟﻠﺒﺤﺚ ﻋﻦ أﻏﻠﻔﺔ ﺟﻮﻳـﺔ ﻋﲆ اﻟﻜﻮاﻛﺐ اﻟﺼـﺨﺮﻳﺔ اﻟﻨﺠﻤﻴـﺔ اﻷﺧـﺮى ) ﻣﺜﻞ ﺗﺮاﺑﻴﺴﺖ 1b- (. إن أول إﺷـﺎرة إﱃ أن اﻟﻜﻮﻛﺐ )55 ﻛﺎﻧﻜﺮي إي ( ﻳﻤﻜﻦ أن ﻳﻜـﻮن ﻟﻪ ﻏﻼف ﺟﻮي ﻛﺒ ﺟـﺎءت ﻣـﻦ ﻗﻴﺎﺳـﺎت ﺟﺔ اﻟ در ﺤﺮارة ﺑﻨﺎءً ﻋﲆ اﻧﺒﻌﺎﺛﻪ اﻟﺤﺮاري أو اﻟﻄﺎﻗﺔ اﻟﺤﺮارﻳﺔ ا ﻨﺒﻌﺜـﺔ ﰲ ﺷـﻜﻞ ﺿـﻮء اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤـﺮاء . إذا ﻛـﺎن اﻟﻜﻮﻛـﺐ ﻣﻐﻄﻰ ﺑﺼﺨﻮر ﻣﻨﺼﻬﺮة داﻛﻨﺔ ﻣﻊ ﻏﻄـﺎء رﻗﻴﻖ ﻣـﻦ اﻟﺼـﺨﻮر ا ﺘﺒﺨـﺮة أ و ﻻ ﻳﻮﺟـﺪ ﻏــﻼف ﺟــﻮي ﻋــﲆ اﻹﻃــﻼق ﻓﻴﺠــﺐ أن ﺗﻨﺎا ﺗﻜﻮن درﺟﺔ ﺣـﺮارة اﻟﺠﺎﻧـﺐ اﻟﻨﻬـﺎري ﺣـﻮاﱄ ٤٠٠٠ در ﺟـﺔ ﻓﻬﺮﻧﻬﺎﻳـﺖ ) ~ ٢٢٠٠ ﺗﻜﻮن درﺟﺔ ﺣﺮارة اﻟﺠﺎﻧﺐ اﻟﻨﻬﺎري ﺣـﻮاﱄ 4000 درﺟــﺔ ﻓﻬﺮﻧﻬﺎﻳــﺖ ) 2200 درﺟــﺔ (. ﻣﺌﻮﻳﺔ »: (ﻫﻮ) ﻗﺎل ﺑﺪﻻً ﻣﻦ ذﻟﻚ أﻇﻬـﺮت ﺎت ﺑﻴﺎﻧ ﻛﺎﻣ ا ﻣ ي درﺟﺔ ﺣﺮارة ﻣﻨﺨﻔﻀﺔ ﺎً ﻧﺴﺒﻴ ﺗﺒﻠﻎ ﺣﻮاﱄ 2800 درﺟﺔ ﻓﻬﺮﻧﻬﺎﻳـﺖ ﺣﻮاﱄ ) 1540 درﺟﺔ ﻣﺌﻮﻳﺔ («. ﻫﺬا ﻣﺆﴍ ﻗـﻮي ﻟﻠﻐﺎﻳـﺔ ﻋـﲆ أن اﻟﻄﺎﻗـﺔ ﺗﺘﻮز ع ﻣﻦ ﺟﺎﻧﺐ اﻟﻨﻬﺎر إﱃ ﺟﺎﻧﺐ اﻟﻠﻴﻞ ﻋﲆ اﻷرﺟﺢ ﻣﻦ ﺧﻼل ﻏﻼف ﺟﻮي ﻣﺘﻘﻠﺐ وﻏﻨ ﻲ وﰲ ﺣ أن ﺗﻴﺎرات اﻟﺤﻤﻢ اﻟﱪﻛﺎﻧﻴﺔ ﻳﻤﻜﻨﻬﺎ أن ﺗﺤﻤ ﻞ ﺑﻌ ﺾ اﻟﺤﺮارة إﱃ اﻟﺠﺎﻧـﺐ اﻟﻠـﻴﲇ ﻓﺈﻧﻬﺎ ﻻ ﺗﺴﺘﻄﻴﻊ ﺗﺤﺮﻳﻜﻬﺎ ﺑﻜﻔﺎءة ﻛﺎﻓﻴـﺔ ﻟﺘﻔﺴ ﺗﺄﺛ اﻟﺘﱪﻳﺪ . ﻋﻨﺪﻣﺎ ﻧﻈﺮ اﻟﻔﺮﻳﻖ إﱃ ﺑﻴﺎﻧﺎت ﻛﺎﻣ ا ﻧ ﻛﺎم رأوا أﻧﻤﺎﻃ ﺎً ﺗﺘﻮاﻓﻖ ﻣﻊ اﻟﻐﻼف اﻟﺠﻮي اﻟﻐﻨﻲ ﺑﻤﻮاد ﻣﺘﻄﺎﻳﺮة أوﺿ. ﺢ ا ﺆﻟﻒ ا ﺸﺎرك آرون أروف ﺑﻴﻠﻮ ﻣﻦ ﻣﺨﺘﱪ اﻟﺪﻓﻊ اﻟﻨﻔﺎث اﻟﺘـﺎﺑﻊ ﻟﻮﻛﺎﻟـﺔ ﻧﺎﺳـﺎ " : ﻧـﺮى دﻟـﻴﻼً ﻋــﲆ وﺟـﻮد اﻧﺨﻔﺎض ﰲ اﻟﻄﻴﻒ ﺑـ 4 و 5 ﻣﻴﻜﺮوﻧـﺎت أﻗﻞ ﻣﻦ ﻫ ﺬا اﻟﻀﻮء اﻟﻮاﺻﻞ إﱃ اﻟﺘﻠﺴﻜﻮب ﻣﺎ ﻳﺸ إﱃ وﺟﻮد ﻏﻼف ﺟﻮي ﻳﺤﺘﻮي ﻋﲆ أول أﻛﺴﻴﺪ اﻟﻜﺮﺑﻮن أو ﺛـﺎﻧﻲ أﻛﺴـﻴﺪ اﻟﻜﺮﺑـﻮن اﻟﺬي ﻳﻤﺘﺺ ﻫﺬه اﻷﻃﻮال ا ﻮﺟﻴﺔ ﻟﻠﻀـﻮء . اﻟﻜﻮﻛﺐ اﻟﺬي ﻟﻴﺲ ﻟﻪ ﻏﻼف ﺟﻮي أو ﻏﻼف ﺘﻜﻮ ﺟﻮي ﻳ ن ﻓﻘﻂ ﻣﻦ اﻟﺼﺨﻮر ا ﺘﺒﺨﺮة ﻟﻦ ﺗ ﻜﻮن ﻟﻪ ﻫﺬه ا ﻴﺰة اﻟﻄﻴﻔﻴﺔ ا ﺤﺪدة . ﻗﺎﻟﺖ ا ﺆﻟ ﻔﺔ ا ﺸﺎرﻛﺔ ﻳـﺎﻣﻴﻼ ﻣﻴﻐﻴـﻞ ﻣـﻦ ﻣﺮﺻﺪ ﻻﻳـﺪن وا ﻌﻬـﺪ اﻟﻬﻮﻟﻨـﺪي ﻷﺑﺤـﺎث اﻟﻔﻀﺎء :" أﻣﻀﻴﻨﺎ اﻟﺴﻨﻮات اﻟﻌﴩ ا ﺎﺿﻴﺔ ﰲ وﺿـﻊ ﻧﻤـﺎذج ﻟﺴـﻴﻨﺎرﻳﻮﻫﺎت ﻣﺨﺘﻠﻔـﺔ ﻟﺘﺨﻴﻞ ﺷﻜﻞ اﻟﻜﻮﻛﺐ ﻫﺬا . ﻳﻌﺘﻘﺪ اﻟﻔﺮﻳﻖ أن اﻟﻐﺎزات اﻟﺘﻲ ﺗﻐﻄﻲ اﻟ ) ﻜﻮﻛﺐ 55 ﻛـﺎﻧﻜﺮي ( إي ﺳﺘﻨﺒﺜﻖ ﻣﻦ اﻟﺪاﺧﻞ ﺑﺪﻻً ﻣﻦ أن ﺗﻜـﻮن ﻣﻮﺟﻮدة ﻣﻨﺬ ﺗﺸﻜﻞ اﻟﻜﻮﻛﺐ . ﻗﺎل ﺑﻴﻠﻮ أروف " : ﺳﻴﺨﺘﻔﻲ اﻟﻐﻼف اﻟﺠـﻮي اﻷﺳﺎﳼ ﻣﻨﺬ ﻓﱰة ﻃﻮﻳﻠـﺔ ﺑﺴـﺒﺐ ارﺗﻔـﺎع درﺟﺔ اﻟﺤﺮارة وا ﻹﺷﻌﺎع اﻟﺸﺪﻳﺪ اﻟﺼﺎدر ﻋﻦ اﻟﻨﺠﻢ و ﺳﻴﻜﻮن ﻫﺬا اﻟﻐﻼف اﻟﺠﻮي ﺛﺎﻧﻮﻳـ ﺎً ﻳﺘﻢ ﺗﺠﺪﻳ ﺪه ﺑﺎﺳﺘﻤﺮار ﺑ ﻤﺤﻴﻂ اﻟﺼﻬﺎرة ﻣﻦ ﺑﻠﻮرات وﺻﺨﻮر ﺳﺎﺋﻠﺔ او ﻟﻜﺜ ﻣـﻦ اﻟﻐـﺎز ا ﺬاب ﻓﻴﻪ أﻳﻀًـﺎ ﰲ ) ﺣـ أن 55 ﻛـﺎﻧﻜﺮي ( إي ﺣﺎر ﺟﺪً ﻻ ﻳﻤﻜﻦ اﻟﻌﻴﺶ ﻓﻴـﻪ، ﻳﻌﺘﻘـﺪ اﻟﺒــﺎﺣﺜﻮن أﻧــﻪ ﻳــﻮﻓﺮ ﻓﺮﺻــﺔ ﻟﺪراﺳــﺔ اﻟﺘﻔﺎﻋﻼت ﺑ اﻟﻐـﻼف اﻟﺠـﻮي واﻷﺳـﻄﺢ وا ﻷﺟﺰاء اﻟﺪاﺧﻠﻴﺔ ﻟﻠﻜﻮاﻛﺐ اﻟﺼﺨﺮﻳﺔ ورﺑﻤﺎ ﻳﻘ ـﺪم ﻧﻈ ـﺮة ﻟﻠﻈ ـﺮو ف ا ﺒﻜ ـﺮة ﻟ ـﻸرض واﻟﺰﻫﺮة وا ﺮﻳﺦ واﻟﺘﻲ ﻳﻌﺘﻘـﺪ أﻧﻬـﺎ ﻛﺎﻧـﺖ ﻣﻐﻄﺎة ﺑﻤﺤﻴﻄﺎت اﻟﺼﻬﺎرة ﰲ ا ﺎﴈ . : "(ﻫﻮ) ﻗﺎل ﻧﺮﻳﺪ ﻓﻬﻢ ﰲ اﻟﻨﻬﺎﻳﺔ اﻟﻈـﺮوف اﻟﺘﻲ ﺗﺠﻌﻞ ﻣﻦ ا ﻤﻜﻦ ﻟﻜﻮﻛﺐ ﺻـﺨﺮي أ ن ﻳﺤﺎﻓﻆ ﻋﲆ ﻏﻼف ﺟﻮي ﻏﻨﻲ ﺑﺎﻟﻐـﺎز وﻫـﻮ ﻋﻨﴫ أﺳﺎﳼ ﻟﻜﻮﻛﺐ ﺻﺎﻟﺢ ﻟﻠﺤﻴﺎة " .