Free Astronomy Magazine July-August 2024 ARABIC VERSION

his light curve shows the change in brightness of the WASP-43 system over time as the planet orbits the star. This type of light curve is known as a phase curve because it includes the entire orbit, or all phases of the planet. Because it is tidally locked, different sides of WASP-43 b rotate into view as it or- bits. The system appears brightest when the hot dayside is facing the telescope, just before and after the secondary eclipse when the planet passes behind the star. The system grows dimmer as the planet continues its orbits and the nightside rotates into view. After the transit when the planet passes in front of the star, blocking some of the starlight, the system brightens again as the dayside rotates back into view. This graph shows more than 8,000 measurements of 5- to 12-micron mid-infrared light captured over a single 24-hour observation using the low-resolution spectroscopy mode on Webb’s MIRI. By subtract- ing the amount of light contributed by the star, astronomers can calculate the amount coming from the visible side of the planet as it orbits. Webb was able to detect differences in brightness as small as 0.004% (40 parts per million). Since the amount of mid-infrared light given off by an object is directly related to its temperature, astronomers were able to use these measurements to calculate the average temperature of different sides of the planet. [Illustration: NASA, ESA, CSA, Ralf Crawford (STScI). Science: Taylor Bell (BAERI), Joanna Barstow (The Open University), Michael Roman (University of Leicester)] “The fact that we can map temper- ature in this way is a real testament to Webb’s sensitivity and stability,” said Michael Roman, a co-author from the University of Leicester in the U.K. To interpret the map, the team used complex 3D atmospheric models like those used to under- stand weather and climate on Earth. The analysis shows that the night- side is probably covered in a thick, high layer of clouds that prevent some of the infrared light from es- caping to space. As a result, the nightside – while very hot – looks dimmer and cooler than it would if there were no clouds. The broad spectrum of mid-infrared light captured by Webb also made it possible to measure the amount of water vapor (H 2 O) and methane (CH 4 ) around the planet. “Webb has given us an opportunity to figure out exactly which mole- cules we’re seeing and put some lim- its on the abundances,” said Joanna Barstow, a co-author from the Open University in the U.K. The spectra show clear signs of water vapor on the nightside as well as the dayside of the planet, provid- ing additional information about how thick the clouds are and how high they extend in the atmosphere. Surprisingly, the data also shows a distinct lack of methane anywhere in the atmosphere. Although the dayside is too hot for methane to exist (most of the carbon should be in the form of carbon monoxide), methane should be stable and de- tectable on the cooler nightside. “The fact that we don’t see methane tells us that WASP-43 b must have wind speeds reaching something like 5,000 miles per hour,” explained Barstow. “If winds move gas around from the dayside to the nightside and back again fast enough, there isn’t enough time for the expected chemical reactions to produce de- tectable amounts of methane on the nightside.” The team thinks that because of this wind-driven mixing, the atmospheric chemistry is the same all the way around the planet, which wasn’t ap- parent from past work with Hubble and Spitzer. The MIRI observation of WASP-43 b was conducted as part of the Webb Early Release Science programs, which are providing researchers with a vast set of robust, open-access data for studying a wide array of cosmic phe- nomena.     ﻈﻬـﺮ اﻟﻀـﻮء ﻫـﺬا اﻟﺘﻐـ ﻓـﻲﺳـﻄﻮع ﻧﻈـﺎم ﻣﻨﺤـ WASP-43 ﻣـﻊ ﻣـﺮور اﻟﻮﻗـﺖ أﺛﻨـﺎء دوران اﻟ ﻮﻛـﺐﺣـﻮل اﻟـﻨ ﻢ . ُﻌـﺮفﻫـﺬا اﻟﻨـﻮع ﻣـﻦ ـﺎت ﻣﻨﺤﻨ اﻟﻄـﻮر ﻷﻧـﮫ ﺸـﻤﻞ اﻟﻤـﺪار ﺄ ﻤﻠــﮫ، أو اﻟﻀـﻮء ﻤﻨﺤـ ﻤﻴﻊ ﻣﺮاﺣﻞ اﻟ ﻮﻛﺐ . ﻧﻈﺮًا ﻷﻧﮫ ﻣﻘ ﺎً ﻣﺪ ﻔﻞ ﻓﺈن ﺟﻮاﻧﺐ ﻣﺨﺘﻠﻔﺔ ﻣ ﻦ WASP-43 b ﺗﺪورﻓﻲ اﻷﻓﻖ أﺛﻨـﺎء ﻇﻬـﻮرﻩ أو أﺟـﺰاء . ﻈﻬـﺮ اﻟﻨﻈـﺎم أﻛـ ﺳـﻄﻮﻋﺎً ﻋﻨـﺪﻣﺎ ﻳﻮاﺟـﮫ ﺟﺎﻧـﺐ اﻟﻨﻬـﺎر اﻟـ ـ ﺤﺎراﻟﺘﻠﺴـ ﻮب ﻗﺒـﻞ و ﻌـﺪ اﻟﻜﺴـﻮف اﻟﺜــﺎﻧﻮيﻣ ﺎﺷـﺮة ﻋﻨـﺪﻣﺎ ﻤـﺮاﻟ ﻮﻛــﺐﺧﻠــﻒ اﻟـﻨ ﻢ ﺼــﺒﺢ اﻟﻨﻈــﺎم ﺧﺎﻓﺘــﺎً ـﺪور اﻟــ ﻣـﻊ اﺳــﺘﻤﺮاراﻟ ﻮﻛــﺐ ﻓــﻲﻣﺪاراﺗـﮫ و ـ ﺠﺎﻧﺐ اﻟﻠ ﻠـﻲﻓـﻲ اﻷﻓــﻖ . ﻌــﺪ اﻟﻌ ﺒـﻮرﻋﻨـﺪﻣﺎ ﻤـﺮ اﻟ ﻮﻛــﺐ أﻣــﺎم اﻟــﻨ ﻢ وﻳﺤﺠﺐ ﻌﻀﺎً ﻣﻦ ﺿﻮء اﻟﻨﺠﻮم ﻀﻲء اﻟﻨﻈﺎم ﻣﺮة أﺧﺮى ﻣﻊ دوران اﻟ ـ ﺠﺎﻧﺐ اﻟﻨﻬﺎريﻣﺮة أﺧﺮى إﻟﻰ اﻟﺮؤ ﺔ . ﻳﻮﺿﺢ ﻫﺬا اﻟﺮﺳﻢ اﻟﺒ ﺎﻧﻲ أﻛ ﻣﻦ 8000 ﻗ ﺎسﻟﻀﻮء اﻷﺷﻌﺔ ﺗﺤﺖ اﻟ ـ ﻤﺮاء اﻟﻤﺘﻮﺳﻄﺔ ﻣﻦ ٥ إﻟﻰ 12 ﻣ ﻜﺮون ﺗﻢ اﻟﺘﻘﺎﻃﻬﺎ ﺧﻼل ﻣﺮاﻗ ﺔ واﺣﺪة ﻣﺪﺗﻬﺎ 24 ﺳﺎﻋﺔ ﺎﺳﺘﺨﺪام اﻟﺘﺤﻠﻴﻞ اﻟﻄ ﻔﻲﻣﻨﺨﻔﺾ اﻟﺪﻗﺔ ﺄداة ﻣ ي ﻟﺘﻠﺴ ﻮب و ﺐ ﺴـﺎﻫﻢ ﺑﻬـﺎ اﻟـﻨ ﻢ وﻣﻦ ﺧﻼل ﻃﺮح ﻤ ﺔ اﻟﻀﻮء اﻟـ ﻤﻜـﻦ ﺣﺴﺎب اﻟ ﻤ ﺔ اﻟﻘﺎدﻣﺔ ﻣﻦ اﻟ ـ ﺠﺎﻧﺐ اﻟﻤﺮﻲﻣﻦ اﻟ ﻮﻛﺐ أﺛﻨﺎء دوراﻧﮫ . ﺗﻤﻜﻦ ﺗﻠﺴ ﻮب و ﺐ ﻣﻦ اﻛﺘﺸﺎف اﺧﺘﻼﻓﺎتﻓﻲ اﻟﺴﻄﻮع ﺗﺼﻞ إﻟﻰ . ) %40 ﺟﺰءًا ﻓﻲ اﻟﻤﻠﻴـ (ﻮن ـﺔ ﺿـﻮء اﻷﺷـﻌﺔ و ﻤـﺎ أن ﻤ ﺗﺤــﺖ اﻟــ ـ ﻤﺮاء اﻟﻤﺘﻮﺳــﻄﺔ اﻟﻤﻨ ﻌﺜــﺔ ﻣــﻦ ﺟﺴــﻢ ﻣــﺎ ﺗــﺮ ﻂ ار ﺎﻃــﺎً ﻣ ﺎﺷــﺮاً ﺪرﺟــﺔ ﺣﺮارــﮫ ﻓﻘــﺪ ﺗﻤﻜــﻦ اﻟ ﻌﻠﻤــﺎء ﻣــﻦ اﺳـﺘﺨﺪام ﻫــﺬﻩ اﻟﻘ ﺎﺳــﺎت ﻟــ ـ ﺤﺴﺎب ﻣﺘﻮﺳــﻂ درﺟــﺔ اﻟــ ـ ـ ﺤﺮارة ﻟــ ﺠﻮاﻧﺐ ﻣﺨﺘﻠﻔــﺔ ﻣــﻦ اﻟ ﻮﻛــﺐ ] Illustration: NASA, ESA, CSA, Ralf Crawford (S ScI). Sci nce: Taylor Bell (BAERI), Joanna Barstow (Th Open University), Michael Roman (Univ rsity of Leicester [( - ﻳﻮﻟﻴﻮ ﺃﻏﺴﻄﺲ 2 0 2 4 ﻗﺎل ﻣﺎﻳﻜﻞ روﻣﺎن ا ﺆﻟﻒ ا ﺸﺎرك ﻣﻦ ﺟﺎﻣﻌﺔ ﻟﻴﺴﱰ ﰲ ا ﻤﻠﻜﺔ ا ﺘﺤﺪة :» إن ﺣﻘﻴﻘﺔ ﻗﺪرﺗﻨﺎ ﻋﲆ رﺳـﻢ ﺧﺮﻳﻄـﺔ ﻟﺪرﺟـﺔ اﻟﺤـﺮارة ﺑﻬـﺬه اﻟﻄﺮﻳﻘﺔ ﻫﻲ ﺷﻬﺎدة ﺣﻘﻴ ﻘﻴﺔ ﻋﲆ ﺣﺴﺎﺳﻴﺔ ﺗﻠﺴﻜﻮب وﻳﺐ واﺳﺘﻘﺮاره « . ﻟﺘﻔﺴ اﻟﺨﺮﻳﻄﺔ اﺳـﺘﺨﺪم اﻟﻔﺮﻳـﻖ ﺻـﻮر اً ﺟﻮﻳﺔ ﻣﻌﻘﺪة ﺛﻼﺛﻴﺔ اﻷﺑﻌﺎد . ﻧﻤﺎذج ﻣﺜﻞ ﺗﻠـﻚ ا ﺴﺘﺨﺪﻣﺔ ﻟﻔﻬﻢ اﻟﻄﻘﺲ وا ﻨﺎخ ﻋﲆ اﻷرض . ﻳﻈﻬﺮ اﻟﺘﺤﻠﻴﻞ أن اﻟﺠﺎﻧﺐ اﻟﻠﻴﲇ رﺑﻤـﺎ ﻳﻜـﻮن ﻣﻐﻄﻰ ﺑﻄﺒﻘﺔ ﺳ ﻤﻴﻜﺔ وﻋﺎﻟﻴﺔ ﻣـﻦ اﻟﺴـﺤﺐ اﻟﺘﻲ ﺗﻤﻨﻊ ﺑﻌﺾ ﺿﻮء اﻷﺷﻌﺔ ﺗﺤﺖ اﻟ ﺤﻤﺮاء ﻣﻦ اﻟﻬﺮوب إﱃ اﻟﻔﻀﺎء وﻧﺘﻴﺠـﺔ ﻟـﺬﻟﻚ ﻳﺒـﺪو اﻟﺠﺎﻧﺐ اﻟﻠﻴﲇ - رﻏﻢ أﻧـﻪ ﺣـﺎر ﺟـﺪ - اً أﻛﺜـﺮ ﻗﺘﺎﻣﺔ وﺑﺮودة ﻣﻤﺎ ﻛﺎن ﻋﻠﻴﻪ ﻟﻮ ﻟﻢ ﺗﻜﻦ ﻫﻨﺎك ﻃﺒﻘﺎت ﻣﻦ اﻟ . ﻐﻴﻮم ﻛﻤﺎ ﻣﻜّﻦ ﺗﺤﻠﻴﻞ اﻟﻄﻴﻒ ﻣـﻦ ﺿـﻮء اﻷﺷـﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ا ﺘﻮﺳﻄﺔ ﻗﻴﺎس ﻛ ﻤﻴـﺔ ﺑﺨـﺎر ا ﺎء ) H2O ( ) وا ﻴﺜﺎن CH4 ( ﺣﻮل اﻟﻜﻮﻛﺐ . ﻗﺎﻟﺖ ﺟﻮاﻧﺎ ﺑﺎرﺳﺘﻮ ا ﺆﻟﻔـﺔ ا ﺸـﺎرﻛﺔ ﻣـﻦ اﻟﺠﺎﻣﻌﺔ ا ﻔﺘﻮﺣﺔ ﰲ ا ﻤﻠﻜﺔ ا ﺘﺤـﺪة ﻟﻘـﺪ »: ﻣﻨﺤﻨــﺎ ﺗﻠﺴــﻜﻮب وﻳــﺐ ﻓﺮﺻــﺔ ﻌﺮﻓــﺔ اﻟﺠﺰﻳﺌﺎت اﻟﺘﻲ ﻧﺮاﻫﺎ ﺑﺎﻟﻀﺒﻂ ووﺿﻊ ﺑﻌـﺾ اﻟﻘﻴﻮد ﻋﲆ وﻓﺮﺗﻬﺎ وﺗﻈﻬﺮ اﻷﻃﻴﺎف ﻋﻼﻣـﺎت واﺿﺤﺔ ﻟﺒﺨﺎر ا ﺎء ﻋﲆ اﻟﺠﺎﻧﺐ اﻟﻠﻴﲇ وﻋـﲆ اﻟﺠﺎﻧــﺐ اﻟﻨﻬـﺎري ﻣـﻦ اﻟﻜﻮﻛـﺐ ﻣـﺎ ﻳـﻮﻓﺮ ﻣﻌﻠﻮﻣﺎت إﺿﺎﻓﻴﺔ ﺣﻮل ﻣﺪى ﻛﺜﺎﻓﺔ اﻟﺴـﺤ ﺐ وارﺗﻔﺎﻋﻬﺎ ﰲ اﻟﻐﻼف اﻟﺠﻮي وا ﺜ ﻟﻠﺪﻫﺸـﺔ أن اﻟﺒﻴﺎﻧﺎت ﺗﻈﻬﺮ أﻳﻀ ﺎَ ﻧﻘﺼ ﺎً ﺎَ واﺿﺤ ﰲ ﻏﺎز ا ﻴﺜﺎن ﰲ أي ﻣﻜﺎن ﰲ اﻟﻐـﻼف اﻟﺠـﻮي وﻋـﲆ اﻟﺮﻏﻢ ﻣﻦ أن اﻟﺠﺎﻧﺐ اﻟﻨﻬـﺎري ﺣـﺎر ﻟﻠﻐﺎﻳـﺔ ﺑﺤﻴﺚ ﻻ ﻳﻤﻜﻦ وﺟﻮد ا ﻴﺜﺎن ) ﻳﺠﺐ أن ﻳﻜﻮن ﻣﻌﻈـﻢ اﻟﻜ ﺮﺑ ـﻮن ﻋ ـﲆ ﺷ ـﻜﻞ أول أﻛﺴـﻴﺪ اﻟﻜﺮﺑــﻮن ( إﻻ أن ا ﻴﺜــﺎن ﻳﺠــﺐ أن ﻳﻜــ ﻮن اً ﻣﺴﺘﻘﺮ وﻳﻤﻜﻦ اﻛﺘﺸﺎﻓﻪ ﰲ اﻟﺠﺎﻧـﺐ اﻟﻠـﻴﲇ اﻷﻛﺜﺮ ﺑﺮودة . أوﺿـﺤ ﺖ ﺑﺎرﺳـﺘﻮ :" ﺣﻘﻴﻘـﺔ ﻋﺪم وﺟﻮد ﻏﺎز ا ﻴﺜﺎن ﺗﺨـﱪﻧﺎ ﺑـﺄن اﻟﻜﻮﻛﺐ WASP-43 b ﻳﺠﺐ أن ﺗﺼﻞ ﴎﻋـﺔ اﻟﺮﻳـﺎح ﻓﻴﻪ إﱃ ﻣﺎ ﻳﻘﺮب ﻣﻦ 5000 ﻣﻴﻞ ﰲ اﻟﺴﺎﻋﺔ . إذا ﻗﺎﻣﺖ اﻟﺮﻳﺎح ﺑﻨﻘﻞ اﻟﻐﺎز ﻣﻦ ﺟﺎﻧﺐ اﻟﻨﻬﺎر إﱃ ﺟﺎﻧﺐ اﻟﻠﻴﻞ ﺛﻢ ﻋﺎدت ﻣﺮة أﺧﺮى ـﺑ ﴪﻋﺔ ﻛﺎﻓﻴﺔ ﻓﻠﻦ ﻳﻜﻮن ﻫﻨﺎك وﻗﺖ ﻛﺎفٍ ﻟﻠﺘﻔﺎﻋﻼت اﻟﻜﻴﻤﻴﺎﺋﻴﺔ ا ﺘﻮﻗﻌـﺔ ﻹﻧﺘـﺎج ﻛﻤﻴـﺎت ﻳﻤﻜـﻦ اﻛﺘﺸﺎﻓﻬﺎ ﻣﻦ ا ﻴﺜﺎن ﰲ اﻟ ﺠﺎﻧﺐ اﻟﻠﻴﲇ . ﻳﻌﺘﻘﺪ اﻟﻔﺮﻳﻖ أﻧﻪ ﺑ ﺴﺒﺐ ﻫـﺬا اﻟﺨﻠـﻂ اﻟـﺬي ﺗﺤﺮﻛﻪ اﻟﺮﻳﺎح ﻓﺈن ﻛﻴﻤﻴﺎء اﻟﻐﻼف اﻟﺠﻮي ﻫﻲ ﻧﻔﺴﻬﺎ ﰲ ﺟﻤﻴﻊ أ ﻧﺤﺎء اﻟﻜﻮﻛﺐ وﻫﻮ ﻣـﺎ ﻟـﻢ ﻳﻜــﻦ واﺿ ـﺤ ﺎً ﰲ اﻷرﺻــﺎ د اﻟﺴ ـﺎﺑﻘﺔ ﻣــﻊ ﺗﻠﺴﻜﻮﺑﻲ ﻫﺎﺑﻞ و ﺳﺒﻴﺘﺰر . ﺗﻢ إﺟﺮاء رﺻﺪ ﻛﺎﻣ ا ﻣ ي ) ﻟﻸﺷﻌﺔ ﺗﺤـﺖ اﻟﺤﻤﺮاء ا ﺘﻮﺳﻄﺔ ( ﻟﻠﻜﻮﻛـﺐ WASP-43 b ﻛﺠﺰء ﻣﻦ ﺑﺮاﻣﺞ اﻹﺻﺪار اﻟﻌﻠﻤﻲ ا ﺒﻜﺮ ﻟﻮﻳﺐ ﻳ ﺬياﻟ ﺰود اﻟﺒﺎﺣﺜ ﺑﻤﺠﻤ ﻮﻋـﺔ واﺳـﻌﺔ ﻣـﻦ اﻟﺒﻴﺎﻧﺎت اﻟﻘﻮﻳﺔ و ﻣﻔﺘﻮﺣﺔ ا ﺼـﺪر ﻟﺪراﺳـﺔ ﻣﺠﻤﻮﻋﺔ واﺳﻌﺔ ﻣﻦ اﻟﻈﻮاﻫﺮ اﻟﻜﻮﻧﻴﺔ .