Free Astronomy Magazine July-August 2024 ARABIC VERSION

A Webb maps weather on WASP-43 b by NASA/ESA/CSA Margaret W. Carruthers & Christine Pulliam n international team of re- searchers has successfully used NASA’s James Webb Space Telescope to map the weather on the hot gas-giant exoplanet WASP-43 b. Precise brightness meas- urements over a broad spectrum of mid-infrared light, combined with 3D climate models and previous ob- servations from other telescopes, suggest the presence of thick, high clouds covering the nightside, clear skies on the dayside, and equatorial winds upwards of 5,000 miles per hour mixing atmospheric gases around the planet. The investigation is just the latest demonstration of the exoplanet science now possible with Webb’s extraordinary ability to measure temperature variations and detect atmospheric gases trillions of miles away. WASP-43 b is a “hot Jupiter” type of exoplanet: similar in size to Jupiter, made primarily of hydrogen and helium, and much hotter than any of the giant planets in our own solar system. Although its star is smaller and cooler than the Sun, WASP-43 b orbits at a distance of just 1.3 million miles – less than 1/25 th the distance between Mercury and the Sun. With such a tight orbit, the planet is tidally locked, with one side contin- uously illuminated and the other in permanent darkness. Although the nightside never receives any direct radiation from the star, strong east- ward winds transport heat around from the dayside. Since its discovery in 2011, WASP-43 b has been observed with numerous telescopes, including NASA’s Hubble and now-retired Spitzer space tele- scopes. “With Hubble, we could clearly see that there is water vapor on the dayside. Both Hubble and Spitzer suggested there might be clouds on the nightside,” explained Taylor Bell, researcher from the Bay Area Environmental Research Insti- tute and lead author of a study pub- lished in Nature Astronomy . “But we needed more precise measure- ments from Webb to really begin mapping the temperature, cloud cover, winds, and more detailed at- mospheric composition all the way around the planet.” Although WASP-43 b is too small, dim, and close to its star for a tele- scope to see directly, its short orbital period of just 19.5 hours makes it ideal for phase curve spectroscopy, a technique that involves measuring tiny changes in brightness of the star-planet system as the planet or- bits the star. Since the amount of JULY-AUGUST 2024 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 18 " و ﺐ" ﻳﺮﺳﻢﺧﺮاﺋﻂﻃﻘﺲ ﻟـ WASP-43 b : ﻘﻠﻢ ﻣﺎرﻏﺮﺖ ﺎروﺛﺮزو ﺑﻮﻟ ﺎم ﻛﺮﺴﺘ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ ﻧﺠـﺢ ﻓﺮﻳﻖ دوﱄ ﻣﻦ اﻟﺒﺎﺣﺜ ﻋﱪ اﺳﺘﺨﺪام ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ اﻟ ﻔﻀـﺎﺋﻲ رﺳـﻢ ﰲ ﺧﺮﻳﻄﺔ ﻟﻠﻄﻘـﺲ ﻋـﲆ اﻟﻜﻮﻛـﺐ اﻟﻨﺠﻤـﻲ اﻟﻌﻤـﻼق اﻟﻐـﺎزي اﻟﺴـﺎﺧﻦ WASP-43 b . ﺗﺸ ﻗﻴﺎﺳﺎت اﻟﺴﻄﻮع اﻟﺪﻗﻴﻘﺔ ﻋﲆ ﻧﻄﺎق واﺳﻊ ﻣﻦ ﺿـﻮء اﻷﺷـﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء ا ﺘﻮﺳــﻄﺔ ﺑﺎﻹﺿـﺎﻓﺔ إﱃ ﻧﻤـﺎذج ﻣﻨﺎﺧﻴ ـﺔ ﺛﻼﺛﻴــﺔ اﻷﺑﻌــﺎ د و أرﺻــﺎد ﺳــﺎﺑﻘﺔ ﻣــﻦ اﻟﺘﻠﺴ ـﻜﻮﺑﺎت اﻷﺧــﺮى إﱃ وﺟ ـﻮد ﺳ ـ ﺤﺐ ﺳﻤﻴﻜﺔ وﻋﺎﻟﻴﺔ ﺗﻐﻄﻲ ﺟﺎﻧﺐ اﻟﻠﻴﻞ وﺳـﻤﺎء ﺻﺎﻓﻴﺔ ﰲ ﺟﺎﻧﺐ اﻟﻨﻬـﺎر ورﻳـﺎح اﺳـﺘﻮاﺋﻴﺔ ﺗ ﺰﻳـﺪ ﻋـﻦ 5000 ﻣﻴـﻞ ﰲ اﻟﺴـﺎﻋﺔ ﺗ ﻤﺘـﺰج ﺑ ﻐﺎزات اﻟﻐﻼف اﻟﺠ ﻮي ﺣﻮل اﻟﻜﻮﻛﺐ . ﻳﻌـﺪ ﻫـﺬا اﻟﺒﺤـﺚ ﻣﺠـﺮ د أﺣـﺪث ﻋـﺮض ﻟﻌﻠـﻢ اﻟﻜﻮاﻛﺐ اﻟ ﻨﺠﻤﻴﺔ اﻟﺬي أﺻـﺒﺢ ﻣﻤﻜﻨًـﺎ اﻵن ﺑﻔﻀﻞ ﻗﺪرة ﺗﻠﺴـﻜﻮب وﻳـﺐ ﻋـﲆ ﻗﻴـﺎس اﻟﺘﻐـ ات ﰲ درﺟـﺎت اﻟﺤـﺮارة و اﻛﺘﺸـﺎف ــــ اﻟﻐﺎزات اﻟﺠﻮﻳﺔ ﻋﲆ ﺑﻌﺪ ﺗﺮﻳﻠﻴﻮﻧﺎت اﻷﻣﻴﺎ . ل WASP-43 b ﻫ ـﻮ ﻧ ـﻮع ﻣ ـﻦ اﻟﻜﻮاﻛ ـﺐ اﻟﻨﺠﻤﻴ ـﺔ " ا ﺸــﱰي اﻟﺴــﺎ " ﺧﻦ ﻳﺸــﺒﻪ ﰲ اﻟﺤﺠﻢ ﻛﻮﻛـﺐ ا ﺸـﱰي وﻳﺘﻜـﻮن ﺑﺸـﻜ ﻞ أﺳﺎﳼ ﻣﻦ اﻟﻬﻴـﺪروﺟ واﻟﻬﻴﻠﻴـﻮم وﻫـﻮ أﻛﺜﺮ ﺳﺨﻮﻧﺔ ﺑﻜﺜ ﻣـﻦ أي ﻣـﻦ اﻟﻜﻮاﻛـﺐ اﻟﻌﻤﻼﻗﺔ ﰲ ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤﴘ . ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ أن ﻧﺠﻤﻪ أﺻﻐﺮ ﺣ ﺎً ﺠﻤ وأﻛﺜـﺮ ﺑـﺮودة ﻣـﻦ اﻟﺸـﻤﺲ إﻻ أن WASP-43 b ﻳـﺪور ﻋـﲆ ﻣﺴﺎﻓﺔ 1.3 ﻣﻠﻴﻮن ﻣﻴﻞ ﻓﻘﻂ أي أﻗـﻞ ﻣـﻦ 1/25 ا ﺴﺎﻓﺔ ﺑ ﻋﻄﺎرد واﻟﺸﻤﺲ ﺑﻤﺜﻞ و ﻫﺬا ا ﺪار اﻟﻀﻴﻖ ﻳﻜﻮن اﻟﻜﻮﻛﺐ ﻣﻐﻠﻖ ﻣﺪﻳﺎً ﺣﻴﺚ ﻳﻜﻮن أﺣﺪ ﺟﺎﻧﺒﻴﻪ ﻣﻀـﺎء ﺑﺎﺳـﺘﻤﺮار واﻵﺧﺮ ﰲ ﻇـﻼم داﺋـﻢ ﻋـﲆ اﻟـﺮﻏﻢ ﻣـﻦ أن اﻟﺠﺎﻧـﺐ اﻟﻠـﻴﲇ ﻻ ﻳﺘﻠﻘـ ﺑـﺪاً ﻰ أ أي إﺷـﻌﺎع ﻣﺒﺎﴍ ﻣﻦ اﻟﻨﺠﻢ إﻻ أن اﻟﺮﻳـﺎح اﻟـ ـ ﴩﻗﻴﺔ اﻟﻘﻮﻳﺔ ﺗﻨﻘﻞ اﻟ ـ ـ ﺤﺮارة ﻣ ﻦ اﻟﺠﺎﻧﺐ اﻟﻨﻬﺎري . ﻣﻨ ـﺬ اﻛﺘﺸ ـﺎﻓﻪ ﰲ ﻋ ـﺎم 2011 ﺗ ـﻢ رﺻـﺪ اﻟﻜﻮﻛﺐ WASP-43 b ﺑﺎﺳـﺘﺨﺪام اﻟﻌﺪﻳـﺪ ﻣﻦ اﻟﺘﻠﺴﻜﻮﺑ ﺎت ﺑﻤﺎ ﰲ ذﻟﻚ ﺗﻠﺴﻜﻮب ﻫﺎﺑ ﻞ وﺗﻠﺴــﻜﻮب ﺳـﺒﻴﺘﺰر ا ﺘﻘﺎﻋـﺪ اﻵن اﻟﺘـﺎﺑﻊ ﻟﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ " . ﺑﺎﺳﺘﺨﺪام ﻫﺎﺑﻞ ﻳﻤﻜﻨﻨـﺎ أن ﻧﺮى ﺑﻮﺿﻮح وﺟﻮد ﺑﺨﺎر ﻣﺎء ﻋﲆ ا ﻟﺠﺎﻧـﺐ اﻟﻨﻬﺎري . أوﺿﺢ ﺗﺎﻳﻠﻮر ﺑﻴـﻞ اﻟﺒﺎﺣـﺚ ﻣـﻦ ﻣﻌﻬـﺪ أﺑﺤـﺎث اﻟﺒﻴﺌـﺔ ﰲ ﻣﻨﻄﻘـﺔ اﻟﺨﻠـﻴﺞ وا ﺆﻟﻒ اﻟﺮﺋﻴﴘ ﻟﺪراﺳﺔ ﻧﺸ ـ ﺮت ﰲ ﻣﺠﻠـﺔ Nature Astronomy ": اﻗﱰح ﻛﻞ ﻣﻦ ﻫﺎﺑﻞ وﺳ ﺒﻴﺘﺰر أﻧﻪ ﻗﺪ ﺗﻜﻮ ن ﻫﻨـﺎك ﺳـﺤﺐ ﻋـﲆ اﻟﺠﺎﻧﺐ اﻟﻠﻴﲇ ﻟﻜﻨﻨﺎ ﻛﻨﺎ ﺑﺤﺎﺟﺔ إﱃ ﻗﻴ ﺎﺳﺎت أﻛﺜﺮ دﻗﺔ ﻣﻦ ﺗﻠﺴﻜﻮب وﻳﺐ ﻟﻠﺒﺪء ﻓﻌﻠﻴـ ﰲ ﺎً رﺳـﻢ ﺧـﺮاﺋﻂ ﻟﺪرﺟـﺔ اﻟﺤـﺮارة واﻟﻐﻄـﺎء اﻟﺴﺤﺎﺑﻲ واﻟﺮﻳﺎح وﺗﻜﻮﻳﻦ اﻟﻐـﻼف اﻟﺠـﻮي اﻷﻛﺜﺮ ﺗﻔﺼﻴﻼً ﰲ ﺟﻤﻴﻊ أﻧﺤﺎء اﻟﻜﻮﻛﺐ ." ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ أن WASP-43 b اً ﺻﻐ ﺟﺪ وﻣﻌ ﺘﻢ وﻗﺮﻳﺐ ﻣﻦ ﻧﺠﻤﻪ ﺑﺤﻴـ ﺚ ﻻ ﻳﻤﻜـﻦ ﻟﻠﺘﻠﺴﻜﻮب رؤﻳﺘﻪ ﻣﺒﺎﴍة ﻓﺈن ﻓﱰة ﻣـﺪاره اﻟﻘﺼـ ة اﻟﺘـﻲ ﺗﺒﻠـﻎ 19.5 ﺳـﺎﻋﺔ ﻓﻘـﻂ ﺗﺠﻌﻠـﻪ ﻣﺜﺎﻟﻴـﺎً ﻟﻠﺘﺤﻠﻴـﻞ اﻟﻄﻴﻔـﻲ ﻨﺤﻨـﻰ اﻟﻄﻮر وﻫﻲ ﺗﻘﻨﻴﺔ ﺗﺘﻀﻤﻦ ﻗﻴﺎس اﻟﺘﻐ ات اﻟﺼـﻐ ة ﰲ اﻟﺴـﻄﻮع ﻣـﻦ ﻧﻈـﺎم اﻟـﻨﺠﻢ واﻟﻜﻮﻛﺐ ﺑﻴﻨﻤﺎ ﻳﺪور اﻟﻜﻮﻛﺐ ﺣﻮل اﻟﻨﺠﻢ . ﺳـﻢر ﺗﺨ ﻠـﻲ ﻳﻮﺿـﺢ ـﺪو اﻟ ﻮﻛـﺐ ـﻒ ﻤﻜـﻦ أن ﻳ ﻛ اﻟﻨ ﻤـﻲ اﻟﻌﻤـﻼق اﻟﻐـﺎزي اﻟﺴـﺎﺧﻦ WASP-43 b ـﻢ ﻳ ﻌـﺪ ﺣـﻮاﻟﻲ ﻫﻮ ﻮﻛﺐ ﺑﺤ ﻢ اﻟﻤﺸ ي ﺪورﺣـﻮل ﻧ 280 ﺳـﻨﺔ ﺿـﻮﺋ ﺔ ـﺔ اﻟﺴـﺪس ﻓـﻲ ﻮﻛ . ـﺪور اﻟ ﻮﻛﺐ ﻋﻠﻰ ﻣﺴﺎﻓﺔ ﺣﻮاﻟﻲ 1.3 ﻣﻠﻴﻮن ﻣﻴﻞ ) 0.014 وﺣﺪة ﻓﻠﻜ ﺔ ( وﻳ ﻤﻞ دورة واﺣـﺪة ﻓـﻲﺣـﻮاﻟﻲ 19.5 . ﺔﺳﺎﻋ ﻧﻈـﺮاً ﻷﻧـﮫ ﻗﺮ ـﺐﺟـﺪ اً ـﻮن ﻣـﻦ ﻧ ﻤـﮫ ﻓﻤـﻦ اﻟﻤﺤﺘﻤـﻞ أن ﻳ WASP-43 b : ﺎً ﻣـﺪ ﻣﻐﻠـﻖ ﻣﻌـﺪل ــﺚ ﻳﻮاﺟــﮫ ﺟﺎﻧــﺐ واﺣـﺪ اﻟــﻨ ﻢ ﻓــﻲ ﻤﻴـﻊ اﻷوﻗــﺎت دوراﻧـﮫ وﻓــ ة ﻣــﺪارﻩ ﻣﺘﻤـﺎﺛﻼن ﺑﺤ ] . NASA, ESA, CSA, Ralf Crawford (STScI [( - ﻳﻮﻟﻴﻮ ﺃﻏﺴﻄﺲ 2 0 2 4