Free Astronomy Magazine March-April 2024 ARABIC VERSION

Infrared Survey Explorer. Webb re- vealed in exquisite detail that W1935 and W2220 appeared to be near clones of each other in composition. They also shared similar brightness, temperatures, and spectral features of water, ammonia, carbon monox- ide and carbon dioxide. The striking exception was that W1935 showed emission from methane, as opposed to the anticipated absorption fea- ture that was observed toward W2220. This was seen at a distinct in- frared wavelength to which Webb is uniquely sensitive. “We expected to see methane be- cause methane is all over these brown dwarfs. But instead of absorbing light, we saw just the opposite: The methane was glowing. My first thought was, what the heck? Why is methane emission coming out of this object?” said Faherty. T he team used computer models to infer what might be behind the emis- sion. The modeling work showed that W2220 had an expected distribution of energy throughout the atmos- phere, getting cooler with increasing altitude. W1935, on the other hand, had a surprising result. The best model favored a temperature inver- sion, where the atmosphere got warmer with increasing altitude. “This temperature inversion is really puzzling,” said Ben Burningham, a co-author from the University of Hertfordshire in England and lead modeler on the work. “We have seen this kind of phenomenon in planets with a nearby star that can heat the stratosphere, but seeing it in an object with no obvious exter- nal heat source is wild.” For clues, the team looked in our own backyard, to the planets of our solar system. The gas giant planets can serve as proxies for what is seen going on more than 40 light-years away in the atmosphere of W1935. The team realized that temperature inversions are prominent in planets like Jupiter and Saturn. There is still ongoing work to understand the causes of their stratospheric heat- ing, but leading theories for the solar system involve external heat- ing by aurorae and internal energy transport from deeper in the atmos- phere (with the former a leading ex- planation). This is not the first time an aurora has been used to explain a brown dwarf observation. Astronomers have detected radio emission com- ing from several warmer brown dwarfs and invoked aurorae as the most likely explanation. Searches were conducted with ground-based telescopes like the Keck Observa- tory for infrared signatures from these radio-emitting brown dwarfs to further characterize the phenom- enon, but were inconclusive. W1935 is the first auroral candidate outside the solar system with the signature of methane emission. It’s also the coldest auroral candidate outside our solar system, with an ef- fective temperature of about 400 degrees Fahrenheit (200 degrees Celsius), about 600 degrees Fahren- heit warmer than Jupiter. In our solar system the solar wind is a primary contributor to auroral processes, with active moons like Io and Enceladus playing a role for planets like Jupiter and Saturn, re- spectively. W1935 lacks a compan- ion star entirely, so a stellar wind cannot contribute to the phenome- non. It is yet to be seen whether an active moon might play a role in the methane emission on W1935. “With W1935, we now have a spec- tacular extension of a solar system phenomenon without any stellar ir- radiation to help in the explana- tion,” Faherty noted. “With Webb, we can really ‘open the hood’ on the chemistry and unpack how sim- ilar or different the auroral process may be beyond our solar system,” she added.     ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 24 اﺳﺘﺨﺪم ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﺗﻠﺴ ﻮبﺟ ﻤﺲو ﺐ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳـﺎ ﻟﺪراﺳـﺔ 12 ـ ﺎً ﻗﺰﻣـ ﺎً ﻨ ـﺎرد . اً ـﺪو ﻳ ﻣﻨﻬـــــ أن اﺛﻨــــ – ﺎ W1935 و W2220 – ـــــﺐ واﻟﺴـــــﻄﻮع ودرﺟـــــﺔ ـــــﺚ اﻟ ﻛ ـــــﺎن ﻣـــــﻦ ﻌﻀـــــﻬﻤﺎ ﻣـــــﻦ ﺣ ﻗﺮ ـ اﻟـــ ﺤﺮارة وﻣـــﻊ ذﻟـــﻚ أﻇﻬـــﺮ W1935 اﻧ ﻌﺎﺛـــ ﺎً ﻣـــﻦ اﻟﻤ ﺜـــﺎن ﻋﻠـــﻰﻋﻜـــﺲﻣـــ ة اﻻﻣﺘﺼـــﺎص اﻟﻤﺘﻮﻗﻌـــﺔ اﻟـــ رﺻــــﺪت ﻓــــﻲ W2220 . ﺘﻮﻗـــــﻊ اﻟﻔﺮ ــــﻖ اﻟﻌﻠﻤـــــﻲ ـــــﺪ ــــﺎت ﺗﻮﻟ ــــﻮن ﻧﺘﻴﺠـــــﺔ ﻟﻌﻤﻠ أن اﻧ ﻌــــﺎث اﻟﻤ ﺜــــﺎن ﻗـــــﺪ ﻳ اﻟﺸﻔﻖ اﻟﻘﻄ . ﻛﺸﻒ اﻟﺘﻠﺴﻜﻮب وﻳـﺐ ﺑﺘﻔﺎﺻـﻴﻞ راﺋﻌـﺔ أن W1935 و W2220 ﻳﺒﺪو أﻧﻬﻤﺎ ﻣﺴﺘﻨﺴـﺨﺎن ﻣﻦ ﺑﻌﻀﻬﻤﺎ اﻟﺒﻌﺾ ﰲ اﻟﺘﻜﻮﻳﻦ ﻛﻤـﺎ أﻧﻬ ﺎ ﻤـ ﻳﺘﻤﺎﺛﻼن أﻳﻀ ﺎً ﰲ اﻟﺴﻄﻮع ودرﺟﺎت اﻟﺤـﺮارة واﻟﺴــﻤﺎت اﻟﻄﻴﻔﻴ ـﺔ ﻟﻠﻤـﺎء واﻷﻣﻮﻧﻴ ـﺎ وأول أﻛﺴﻴﺪ اﻟﻜﺮﺑﻮن وﺛﺎﻧﻲ أﻛﺴﻴﺪ اﻟﻜﺮﺑﻮن وﻛـﺎن اﻻﺳﺘﺜﻨﺎء ا ﺬﻫﻞ ﻫﻮ أن W1935 أﻇﻬﺮ اﻧﺒﻌﺎﺛ ﺎً ﻣﻦ ا ﻴﺜـﺎن ﻋـﲆ ﻋﻜـﺲ ﻣﻴـﺰة اﻻﻣﺘﺼـﺎص ا ﺘﻮﻗﻌﺔ اﻟﺘﻲ ﰲ رﺻﺪت W2220 وﻗﺪ ﺷﻮﻫﺪ ﻫﺬا ﻋﻨﺪ ﻃﻮل ﻣﻮﺟﺔ اﻷﺷﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء ا ﻤﻴﺰة اﻟﺘﻲ ﻳﻜﻮن ﺗﻠﺴﻜﻮب وﻳﺐ ﺣﺴﺎﺳ ﺎ ﻟﻬﺎ ﺑﺸﻜﻞ اﺳﺘﺜﻨﺎﺋﻲ ﻗﺎل ﻓﻬﺮﺗﻲ : " ﻟﻘﺪ ﺗﻮﻗﻌﻨﺎ رؤﻳﺔ ﻏﺎز ا ﻴﺜﺎن ﻷن ا ﻴﺜﺎن ﻣﻮﺟﻮد ﰲ ﺟﻤﻴﻊ أﻧﺤﺎء ﻫـﺬه اﻷﻗـﺰام اﻟﺒﻨﻴﺔ . ﻟﻜﻦ ﺑﺪﻻً ﻣﻦ اﻣﺘﺼﺎص اﻟﻀـﻮء رأﻳﻨـﺎ اﻟﻌﻜﺲ ﺗﻤﺎﻣ :ﺎً ﻛﺎن ا ﻴﺜﺎن ﻣﺘﻮﻫﺠﺎً و ﻓﻜﺮﺗـﻲ اﻷوﱃ ﻛﺎﻧﺖ ﻣـﺎ اﻟـﺬي ﻳﺤـﺪث ؟ ـﺎذا ﻳﺨـﺮج اﻧﺒﻌﺎث ا ﻴﺜﺎن ﻣﻦ ﻫﺬا اﻟﺠﺴﻢ؟ . اﺳﺘﺨﺪم اﻟﻔﺮﻳﻖ ﻧﻤﺎذج ﺣﺎﺳﻮﺑﻴﺔ ﻻﺳـﺘﻨﺘﺎج ﻣﺎ ﻗﺪ ﻳﻜﻮن وراء اﻻﻧﺒﻌﺎث . أﻇﻬـﺮت أﻋﻤـﺎل اﻟﻨﻤﺬﺟﺔ أن اﻟﻘﺰم اﻟﺒﻨﻲ W2220 ﻛـﺎن ﻟﺪﻳـﻪ ﺗﻮزﻳﻊ ﻣﺘﻮﻗﻊ ﻟﻠ ﻄﺎﻗﺔ ﰲ ﺟﻤﻴﻊ أﻧﺤﺎء اﻟﻐﻼف اﻟﺠﻮي ﺒﺢ ﺣﻴﺚ ﻳﺼ أﻛﺜﺮ ﺑـﺮودة ﻣـﻊ زﻳـﺎدة اﻻرﺗﻔﺎع . ﻣﻦ ﻧﺎﺣﻴﺔ أﺧﺮى ﻛﺎن ﻟﻠﻘـﺰم اﻟﺒﻨـﻲ W1935 ﻧﺘﻴﺠﺔ ﻣﺬﻫﻠﺔ ﻛﺎن ﻓﻘﺪ ﻳﻔﻀﻞ اﻧﻌﻜﺎس درﺟﺔ اﻟﺤﺮارة ﺣﻴﺚ ﻳﺼﺒﺢ اﻟﻐﻼف اﻟﺠﻮي أﻛﺜﺮ دﻓﺌ ﺎً ﻣﻊ زﻳﺎدة اﻻرﺗﻔﺎع . ﻗﺎل ﺑﻦ ﺑ ﻧﻨﺠﻬﺎم ا ﺆﻟﻒ ا ﺸﺎرك ﻣﻦ ﺟﺎﻣﻌﺔ ﻫ ﺗﻔﻮردﺷﺎﻳﺮ ﰲ إﻧﺠﻠﱰا وﻣﺼـﻤﻢ اﻟﻨﻤـﺎذج اﻟﺮﺋﻴ ـ : " ﴘ ﰲ ﻫﺬا اﻟﻌﻤﻞ إن ﻫـﺬا اﻟﺘﻘﻠـﺐ ﰲ درﺟﺔ اﻟﺤﺮارة أﻣﺮ ﻣﺤ ﺑﺎﻟﻔﻌﻞ . ﻟﻘﺪ رأﻳﻨﺎ ﻫﺬا اﻟﻨﻮع ﻣﻦ اﻟﻈﺎﻫﺮة ﰲ اﻟﻜﻮاﻛﺐ اﻟﺘﻲ ﻳﻜﻮن ﻟﺪﻳﻬﺎ ﻧﺠﻢ ﻗﺮﻳ ﺐ ﻳﻤﻜﻨﻪ ﺗﺴـﺨ ﻃﺒﻘﺔ اﻟﺴﱰاﺗﻮﺳﻔ وﻟﻜﻦ رؤﻳﺘﻬﺎ ﰲ ﺟﺴـﻢ ﻟﻴﺲ ﻟﻪ ﻣﺼﺪر ﺣﺮارة ﺧـﺎرﺟﻲ واﺿـﺢ ﻫـﻮ ﺑﺎﻟﻔﻌﻞ أﻣﺮ ﻏﺮﻳﺐ ." ﻟﻠﺤﺼﻮل ﻋﲆ أدﻟﺔ ﺑﺤﺚ اﻟﻔ ﺮﻳﻖ ﰲ ﰲ اﻟﻔﻀﺎء اﻟﻘﺮﻳﺐ إﱃ ﻛﻮاﻛﺐ ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤﴘ . ﻳﻤﻜﻦ أن ﺗﻜﻮن اﻟﻜﻮاﻛـﺐ اﻟﻐﺎزﻳـﺔ اﻟﻌﻤﻼﻗـﺔ ﺑﻤﺜﺎﺑـﺔ اﻟﻮﻛﻼء ﺎ ﻳﺤﺪث ﻋﲆ ﺑﻌﺪ أﻛﺜﺮ ﻣﻦ 40 ﺳـﻨﺔ ﺿـﻮﺋﻴﺔ ﰲ اﻟﻐــﻼف اﻟﺠــﻮي ﻟﻠﻘــﺰم اﻟﺒﻨــﻲ W1935 . أدرك اﻟﻔﺮﻳﻖ أن اﻟﺘﻘﻠﺒﺎت ﰲ درﺟﺎت اﻟﺤﺮارة ﺗﻜﻮن ﺑﺎرزة ﰲ ﻛﻮاﻛﺐ ﻣﺜﻞ ا ﺸﱰي . وزﺣﻞ ﻻ ﻳﺰال ﻫﻨـﺎك ﻋﻤـﻞ ﻣﺴـﺘﻤﺮ ﻟﻔﻬـﻢ أﺳــﺒﺎب ﺗﺴــﺨ اﻟﺴﱰاﺗﻮﺳــﻔ ، ﻟﻜــﻦ اﻟﻨﻈﺮﻳﺎت اﻟﺮاﺋﺪة ﻟﻠﻨﻈﺎم اﻟﺸ ـ ﻤﴘ ﺗﺘﻀـﻤﻦ اﻟﺘﺴـﺨ اﻟﺨـﺎرﺟﻲ ﻋ ـﻦ ﻃﺮﻳ ـﻖ اﻟﺸــﻔﻖ اﻟﻘﻄﺒﻲ وﻧﻘﻞ اﻟﻄﺎﻗﺔ اﻟﺪاﺧﻠﻴـﺔ ﻣـﻦ أﻋﻤـﺎق اﻟﻐﻼف اﻟﺠﻮي ﻣﻊ ) اﻟﺘﻔﺴ اﻷول .( ﻟﻴﺴﺖ ﻫﺬه ﻫﻲ ا ـﺮة اﻷوﱃ اﻟﺘـﻲ ﻳـﺘﻢ ﻓﻴﻬـﺎ اﺳﺘﺨﺪام اﻟﺸﻔﻖ اﻟﻘﻄﺒﻲ ﻟﴩح أرﺻﺎد اﻟﻘﺰم اﻟﺒﻨﻲ . اﻛﺘﺸﻒ ﻋﻠﻤﺎء اﻟﻔﻠﻚ اﻧﺒﻌﺎﺛـ ﺎً ﺎً رادﻳﻮﻳـ ﺎً ﻗﺎدﻣ ﻣﻦ اﻟﻌﺪ ﻳﺪ ﻣﻦ اﻷﻗﺰام اﻟﺒﻨﻴﺔ اﻷﻛﺜﺮ دﻓﺌﺎ واﺳﺘﺸــﻬﺪوا ﺑﺎﻟﺸــﻔﻖ اﻟﻘﻄﺒ ـ ﻲ ﺑﺎﻋﺘﺒ ـﺎره اﻟﺘﻔﺴ اﻷﻛﺜﺮ ﺗﺮﺟﻴﺤ .ﺎً ﺗــﻢ إﺟــﺮاء ﻋﻤﻠﻴــﺎت اﻟﺒﺤــﺚ ﺑﺎﺳــﺘﺨﺪام اﻟﺘﻠﺴـﻜﻮﺑﺎت اﻷرﺿـﻴﺔ ﻣﺜـﻞ ﻣﺮﺻــﺪ ﻛﻴ ـﻚ ﻟﺘﻮﻗﻴﻌﺎت اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤـﺮاء ﻣـﻦ ﻫـﺬه اﻷﻗﺰام اﻟﺒﻨﻴـﺔ اﻟﺘـﻲ ﺗﻨﺒﻌـﺚ ﻣﻨﻬـﺎ ﻣﻮﺟـﺎت رادﻳﻮ ﻳﺔ ﻟﺘﻮﺻﻴﻒ ﻫﺬه اﻟﻈﺎﻫﺮة ﺑﺸﻜﻞ أﻛـﱪ وﻟﻜﻨﻬﺎ ﻟﻢ ﺗﻜﻦ ﺣﺎﺳﻤﺔ . W1935 ﻫﻮ أول ﻣﺮﺷﺢ ﻳﺤﺪث ﻓﻴﻪ اﻟﺸـﻔﻖ اﻟﻘﻄﺒﻲ ﻧﻈﺎﻣ ﺧـﺎرج ﻨـﺎ اﻟﺸﻤـ ـ ﴘ ﻳﺤﻤـﻞ ﺗﻮﻗﻴﻊ اﻧﺒﻌﺎث ا ﻴﺜﺎن وﻫﻮ أﻳﻀًﺎ أﺑ ﺮد ﻣﺮﺷـﺢ ﺷﻔﻘﻲ ﺧﺎرج ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤ ﴘـ ﺣﻴﺚ ﺗﺒﻠﻎ درﺟﺔ اﻟﺤـﺮارة اﻟﻔﻌﻠﻴـﺔ ﺣـﻮاﱄ 400 درﺟـﺔ ﻓﻬﺮﻧﻬﺎﻳﺖ ) 200 درﺟـﺔ ﻣﺌﻮﻳـﺔ ( أي ﺣـ ﻮاﱄ 600 درﺟﺔ ﻓﻬﺮﻧﻬﺎﻳﺖ أﻛﺜﺮ دﻓﺌﺎ ﻣـﻦ ﻛﻮﻛـﺐ ا ﺸﱰي . ﺗﻌﺪ اﻟﺮﻳﺎح اﻟﺸﻤﺴـﻴﺔ ﰲ ﻧﻈﺎﻣﻨـﺎ اﻟﺸﻤـ ﴘـ ﺎُ ﻣﺴﺎﻫﻤ أﺳﺎﺳﻴ ﺎً ﰲ ﻋﻤﻠﻴﺎت اﻟﺸﻔﻖ اﻟﻘﻄﺒﻲ ﺣﻴ ـﺚ ﺗﻠﻌ ـﺐ اﻷﻗﻤ ـﺎ ر اﻟﻨﺸـﻄﺔ ﻣﺜ ـﻞ آﻳ ـﻮ وإﻧﺴﻴﻼدوس دور ا ﰲ اﻟﻜﻮاﻛﺐ ﻣﺜﻞ ا ﺸـﱰي وزﺣﻞ ﻋﲆ اﻟﺘﻮاﱄ . ﻳﻔﺘﻘﺮ اﻟﻘﺰم اﻟﺒﻨﻲ W1935 إﱃ ﻧﺠـﻢ ﻣﺮاﻓـﻖ ﺗﻤﺎﻣـﺎً ﻟــﺬﻟﻚ ﻻ ﻳﻤﻜـﻦ ﻟﻠﺮﻳـﺎح اﻟﻨﺠﻤﻴـﺔ أن ﺗﺴﺎﻫﻢ ﰲ ﻫﺬه اﻟﻈﺎﻫﺮة . ﻟﻢ ﻳﺘﻀﺢ ﺑﻌﺪ ﻣﺎ إذا ﻛﺎن اﻟﻘﻤـﺮ اﻟﻨﺸـﻂ ﻗـﺪ ﻳﻠﻌﺐ دورًا ﰲ اﻧﺒﻌﺎث ا ﻴﺜﺎن ﻋﲆ W1935 . أﺷﺎر ﻓﺎﻫﺮﺗﻲ " : ﻣـﻊ اﻟﻘـﺰم اﻟﺒﻨـﻲ W1935 ﻟـﺪﻳﻨﺎ اﻵن اﻣﺘــﺪاد ﻣــﺬﻫﻞ ﻟﻈـﺎﻫﺮة اﻟﻨﻈـﺎم اﻟﺸﻤ ـ ﴘ دون أي إﺷﻌﺎع ﻧﺠﻤﻲ ﻟﻠﻤﺴـ ﺎﻋﺪة ﰲ اﻟﺘﻔﺴ ." وأﺿﺎف " : ﻣﻊ ﺗﻠﺴﻜﻮب وﻳـﺐ ﻳﻤﻜﻨﻨـ ﺎ ﻓـﺘﺢ اﻟﻐﻄﺎء ﻋﲆ اﻟﻜﻴﻤﻴﺎء وﻛﺸﻒ ﻣﺪى ﺗﺸـﺎﺑﻪ أو اﺧﺘﻼف اﻟﻌﻤﻠﻴﺎت ا ﺴﺌﻮﻟﺔ ﻋﻦ ﺣﺪوث اﻟﺸﻔﻖ اﻟﻘﻄﺒﻲ ﺧﺎرج ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤﴘ ." - ﻣﺎﺭﺱ ﺃﺑﺮﻳﻞ 2 0 2 4