Free Astronomy Magazine March-April 2024 ARABIC VERSION

exocomets, and two im- aged exoplanets,” said Rebollido, lead author of the study. “While there have been previ- ous observations from the ground in this wave- length range, they did not have the sensitivity and the spatial resolu- tion that we now have with Webb, so they did- n’t detect this feature.” Even with Webb, or JWST, peering at Beta Pic in the right wave- length range — in this case, the mid-infrared — was crucial to detect the cat’s tail, as it only ap- peared in the MIRI data. Webb’s mid-infrared data also re- vealed differences in temperature between Beta Pic’s two disks, which likely is due to differences in com- position. “We didn’t expect Webb to reveal that there are two different types of material around Beta Pic, but MIRI clearly showed us that the material of the secondary disk and cat’s tail is hotter than the main disk,” said Christopher Stark, a co-author of the study at NASA’s Goddard Space Flight Center in Greenbelt, Mary- land. “The dust that forms that disk and tail must be very dark, so we don’t easily see it at visible wave- lengths — but in the mid-infrared, it’s glowing.” To explain the hotter temperature, the team deduced that the dust may be highly porous “organic refrac- tory material,” similar to the matter found on the surfaces of comets and asteroids in our solar system. For ex- ample, a preliminary analysis of ma- terial sampled from asteroid Bennu by NASA’s OSIRIS-REx mission found it to be very dark and carbon-rich, much like what MIRI detected at Beta Pic. However, a major lingering question remains: What could explain the shape of the cat’s tail, a uniquely curved feature unlike what is seen in disks around other stars? Rebollido and the team modeled various scenarios in an attempt to emulate the cat’s tail and unravel its origins. Though further research and testing is required, the team presents a strong hypothesis that the cat’s tail is the result of a dust production event that occurred a mere one hundred years ago. “Something happens — like a colli- sion — and a lot of dust is pro- duced,” shared Marshall Perrin, a co-author of the study at the Space Telescope Science Institute in Balti- more, Maryland. “At first, the dust goes in the same orbital direction as its source, but then it also starts to spread out. The light from the star pushes the smallest, fluffiest dust particles away from the star faster, while the bigger grains do not move as much, creating a long tendril of dust.” “The cat’s tail feature is highly un- usual, and reproducing the curva- ture with a dynamical model was difficult,” explained Stark. “Our model re- quires dust that can be pushed out of the sys- tem extremely rapidly, which again suggests it’s made of organic re- fractory material.” The team’s preferred model explains the sharp angle of the tail away from the disk as a simple op- tical illusion. Our per- spective combined with the curved shape of the tail creates the observed angle of the tail, while in fact, the arc of mate- rial is only departing from the disk at a five- degree incline. Taking into consideration the tail’s bright- ness, the team estimates the amount of dust within the cat’s tail to be equivalent to a large main belt asteroid spread out across 10 billion miles. A recent dust production event within Beta Pic’s debris disks could also explain a newly-seen asymmet- ric extension of the inclined inner disk, as shown in the MIRI data and seen only on the side opposite of the tail. Recent collisional dust pro- duction could also account for a fea- ture previously spotted by the Atacama Large Millimeter/submil- limeter Array in 2014: a clump of carbon monoxide (CO) located near the cat’s tail. Since the star’s radia- tion should break down CO within roughly one hundred years, this still- present concentration of gas could be lingering evidence of the same event. “Our research suggests that Beta Pic may be even more active and chaotic than we had previously thought,” said Stark. “JWST contin- ues to surprise us, even when look- ing at the most well-studied objects. We have a completely new window into these planetary systems.”     ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 39 - ﻣﺎﺭﺱ ﺃﺑﺮﻳﻞ 2 0 2 4 رﺳﻢ ﻣﺘﺤﺮك ﺼﻮر ﺸ ﮫ اﻟﺸ ﻞ اﻟﺬ ذﻳﻞ اﻟﻘﻄﺔ اﻓ ﺿـﮫ ﻓﺮ ـﻖ ﻣـﻦ ﻋﻠﻤـﺎء اﻟـﺬ اﻟﻔﻠﻚ وﺑﺤﺴﺐ اﻟﺘﻘﺪﻳﺮات ن ﻓﺈ ﻫﺬا اﻟﻬﻴ ﻞ ـﺰء اﻟـ ﻈﻬﺮﻓﻲ ا اﻟﺬ ـ ﺠﻨﻮﺑﻲ اﻟﻐﺮ ـﻲ ﻣﻦ ﻗﺮص اﻟ ـ ﺤﻄﺎم اﻟﺜﺎﻧﻮي ﻟ ﻨﻈﺎم ﺑ ﻜﺘﻮرﺲ ﻤﺘﺪ ﻋﻠﻰ ﻣﺴﺎﻓﺔ 10 ﻣﻠ ﺎرات ﻣﻴﻞ . ﻗﺎل رﻳﺒﻮﻟﻴﺪو ا ﺆﻟﻒ اﻟﺮﺋ ﻴﴘ ـ ﻟﻠﺪراﺳ : "ﺔ إﻧﻨﺎ ﻧﺸـﻬﺪ وﺟـﻮد ﻣﺬﻧﺒﺎت ﻧﺠﻤﻴـﺔ واﺛﻨـ ﻣـﻦ اﻟﻜﻮاﻛـﺐ اﻟ ﻨﺠﻤﻴـﺔ ا ﺼـﻮرة ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ وﺟﻮد أرﺻـﺎد ﺳﺎﺑﻘﺔ ﻣـﻦ اﻷرض ﰲ ﻧﻄـﺎق اﻟﻄﻮل ا ﻮﺟﻲ ﻫﺬا إﻻ أﻧﻬ ﻟﻢ ﺎ ﻳﻜﻦ ﻟﺪﻳﻬ ﺎ اﻟﺤﺴﺎﺳﻴﺔ واﻟﺪﻗﺔ ا ﻜﺎﻧﻴﺔ اﻟﺘـﻲ ﻟـﺪﻳﻨﺎ اﻵن ﻣـﻊ ﺗﻠﺴــﻜﻮب وﻳــﺐ ﻟــﺬﻟﻚ ﻟــﻢ ﻳﻜﺘﺸﻔﻮا ﻫﺬه اﻷﺷﻜﺎل ﺣﺘـﻰ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮب ﺟـ ﻴﻤﺲ وﻳ ـﺐ ﻛـﺎن اﻟﻨﻈـﺮ إﱃ ﺑﻴﺘ ـﺎ ﺑﻴﻜﺘﻮرﻳﺲ ﰲ ﻧﻄـﺎق اﻟﻄـﻮل ا ـﻮﺟﻲ اﻟﺼــﺤﻴﺢ ﰲ ﻫــﺬه اﻟﺤﺎﻟ ﺔ، اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ا ﺘﻮﺳــﻄﺔ أﻣــﺮ اً ﺎً ﺣﺎﺳــﻤ ﻟﻠﻜﺸﻒ ﻋﻦ ذﻳﻞ اﻟﻘﻄﺔ ﻷﻧـﻪ ﻇﻬﺮ ﻓﻘﻂ ﰲ ﺑﻴﺎﻧﺎت ﻛﺎﻣ ا ﻣ ي . ﻛﺸﻔﺖ ﺑﻴﺎﻧﺎت اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤﻤـﺮاء ا ﺘﻮ ﺳـﻄﺔ اﻟﺨﺎﺻــﺔ ﺑ ﺘﻠﺴــﻜﻮب وﻳــﺐ أﻳﻀــ ﺎً ﻋــﻦ اﺧﺘﻼﻓﺎت ﰲ درﺟﺔ اﻟﺤﺮارة ﺑ ﻗﺮﴆ ﺑﻴﺘﺎ ﺑﻴﻜﺘﻮرﻳﺲ واﻟﺬي ﻣـﻦ ا ﺤﺘﻤـﻞ أن ﻳﻜـﻮن ﺑﺴﺒﺐ اﻻﺧﺘﻼﻓﺎت ﰲ اﻟﱰﻛﻴﺐ . ﻗﺎل ﻛﺮﻳﺴﺘﻮﻓﺮ ﺳـﺘﺎرك ا ﺆﻟـﻒ ا ﺸـﺎرك ﻟﻠﺪراﺳﺔ ﻣﻦ ﻣﺮﻛﺰ ﺟﻮدارد ﻟﺮﺣﻼت اﻟﻔﻀﺎء اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳﺎ ﰲ ﺟﺮﻳﻨﺒﻴﻠﺖ ﺑﻮﻻﻳﺔ ﻣﺎرﻳﻼﻧﺪ :. " ﻟﻢ ﻧﺘﻮﻗﻊ أن ﻳﻜﺸـﻒ ﺗﻠﺴـﻜﻮب وﻳـﺐ أن ﻫﻨﺎك ﻧﻮﻋ ﻣﺨﺘﻠﻔ ﻣﻦ ا ﻮاد ﺣﻮل ﺑﻴﺘـﺎ ﺑﻴﻜﺘﻮرﻳﺲ ﻟﻜﻦ ﻛﺎﻣ ا ﻣ ي أﻇﻬﺮ ت ﻟﻨـﺎ ﺑﻮﺿﻮح أن ﻣﺎدة اﻟﻘـﺮص اﻟﺜـﺎﻧﻮي وذﻳـﻞ اﻟﻘﻄ ﺔ أﻛﺜﺮ ﺳﺨﻮﻧﺔ ﻣﻦ اﻟﻘﺮص اﻟﺮﺋﻴﺴ ﻲـ ﻳﺠﺐ أن ﻳﻜﻮن اﻟﻐﺒـﺎر ا ﻟـﺬي ﻳﺸـﻜﻞ ﻫـﺬا اﻟﻘﺮص واﻟﺬﻳﻞ داﻛﻨـ ﺎً اً ﺟـﺪ ﻟـﺬا ﻻ ﻳﻤﻜﻨﻨـﺎ رؤﻳﺘﻪ ﺑﺴﻬﻮ ﻟﺔ ﻋﻨﺪ اﻷﻃﻮال ا ﻮﺟﻴﺔ ا ﺮﺋﻴﺔ و ﻟﻜﻦ ﰲ ﻣﻨﺘﺼﻒ اﻷﺷـﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء ﻓﻬﻮ ﻣﺘﻮﻫﺞ ﻟ. ﺘﻔﺴ درﺟﺔ اﻟﺤﺮارة اﻷﻛﺜﺮ ﺳﺨﻮﻧﺔ اﺳﺘﻨﺘﺞ اﻟﻔﺮﻳﻖ أن اﻟﻐﺒﺎر ﻗﺪ ﻳﻜﻮن ﻋﺒ ـ ﺎرة ﻋ ـﻦ " ﻣــﺎدة ﻋﻀـﻮﻳﺔ ﺣﺮارﻳ ـﺔ " ﻣﺴﺎﻣﻴﺔ ﻟﻠﻐﺎﻳﺔ، ﺗﺸﺒﻪ ا ﺎدة ا ﻮﺟﻮدة ﻋﲆ أﺳﻄﺢ ا ـﺬﻧﺒﺎت واﻟﻜﻮﻳﻜﺒـﺎت ﰲ ﻧﻈﺎﻣﻨـﺎ اﻟﺸﻤﴘ . ﻋﲆ ﺳﺒﻴﻞ ا ﺜـﺎل وﺟـﺪ اﻟﺘﺤﻠﻴـﻞ اﻷوﱄ ﻟﻠﻤﻮاد ا ﺄﺧﻮذة ﻣﻦ اﻟﻜﻮﻳﻜـﺐ ﺑﻴﻨـﻮ ﺑﻮاﺳﻄﺔ ﻣﻬﻤﺔ أوﺳﺎﻳﺮس - رﻛﺲ اﻟﺘﺎﺑﻌﺔ ﻟﻮﻛﺎﻟﺔ ﻧﺎﺳـﺎ أﻧﻬـﺎ ﻣﻈﻠﻤـﺔ ﺟـﺪ اً وﻏﻨﻴـﺔ ﺑﺎﻟﻜﺮﺑﻮن ﺗﻤﺎﻣ ﺎً ﻣﺜﻞ ﻣﺎ اﻛﺘﺸـﻔ ﻪﺘ ﻛـﺎﻣ ا ﻧﻈﺎم ﰲ ﻣ ي ﺑﻴﺘﺎ ﺑﻴﻜﺘﻮرﻳﺲ . ﻣﻊ ذﻟﻚ، ﻳﺒﻘﻰ ﺳﺆال ﻛﺒ ﻋﺎﻟﻘ : ﺎً ﻣﺎ اﻟـﺬي ﻳﻤﻜﻦ أن ﻳﻔﴪ ﺷﻜﻞ ذﻳـﻞ اﻟﻘﻄـ ﺔ وﻫـﻮ ﻣﻴﺰة ﻣﻨﺤﻨﻴﺔ ﺑﺸﻜﻞ ﻓﺮﻳﺪ ﻋﲆ ﻋﻜـﺲ ﻣـﺎ ﻳُﺮى ﰲ اﻷﻗﺮاصﺣﻮل اﻟﻨﺠﻮم اﻷﺧﺮى؟ ﻗ ــﺎم رﻳﺒﻮﻟﻴ ــﺪو واﻟﻔﺮﻳ ــﻖ ﺑﺘﺼ ــﻤﻴﻢ ﺳﻴﻨﺎرﻳﻮﻫﺎت ﻣﺨﺘﻠﻔﺔ ﰲ ﻣﺤﺎو ﻟﺔ ﺤﺎﻛـﺎة ذﻳﻞ اﻟﻘﻄﺔ وﻛﺸﻒ أﺻﻮﻟﻪ ﻋﲆ اﻟﺮﻏﻢ ﻣـﻦ اﻟﺤ ﺎﺟﺔ إﱃ ﻣﺰﻳﺪ ﻣـﻦ اﻟﺒﺤـﺚ واﻻﺧﺘﺒـﺎر . ﻳﻘﺪم اﻟﻔﺮﻳﻖ ﻓﺮﺿﻴﺔ ﻗﻮﻳﺔ ﻣﻔﺎدﻫﺎ أن ذﻳﻞ اﻟﻘﻄ ﺔ ﻫﻮ ﻧﺘ ﻴﺠﺔ ﻟﺤﺪث إﻧﺘﺎج اﻟﻐﺒﺎر اﻟﺬي ﺣﺪث ﻗﺒﻞ ﻣﺎﺋﺔ ﻋﺎم ﻓﻘﻂ . ﻳﻘﻮل ﻣﺎرﺷـﺎل ﺑ ﻳﻦ ا ﺆﻟﻒ ا ﺸﺎرك ﻟﻠﺪراﺳﺔ ﻣـﻦ ﻣﻌﻬـﺪ ﻋﻠـﻮم اﻟﺘﻠﺴـﻜﻮب اﻟﻔﻀـﺎﺋﻲ ﰲ ﺑـﺎﻟﺘﻴﻤﻮر ﺑﻮﻻﻳﺔ ﻣﺎرﻳﻼﻧـﺪ " : ﻳﺤـﺪثﳾء ﻣـﺎ ﻣﺜـﻞ اﻻﺻﻄﺪام وﻳﺘﻢ إﻧﺘﺎج اﻟﻜﺜـ ﻣـﻦ اﻟﻐﺒـﺎر ﺣﻴـﺚ ﰲ اﻟﺒﺪاﻳـﺔ ﻳﺴـ اﻟﻐﺒــﺎ ر ﰲ ﻧﻔـﺲ اﻻﺗﺠﺎه ا ﺪاري ﺼﺪره ﻟﻜﻨﻪ ﻳﺒـﺪأ أﻳﻀـ ﰲ ﺎً اﻻﻧﺘﺸﺎر إن . اﻟﻀـﻮء اﻟﺼـﺎدر ﻣـﻦ اﻟـﻨﺠﻢ ﻳﺪﻓﻊ ﺟﺰﻳﺌﺎت اﻟﻐﺒﺎر اﻷﺻﻐﺮ واﻷﻛﺜ ﺮ رﻗـﺔ ﺑﻌﻴﺪًا ﻋﻦ اﻟﻨﺠﻢ ﺑﺸـﻜﻞ أﴎع ﰲ ﺣـ أن اﻟﺤﺒﻴﺒﺎت اﻷﻛﱪ ﻻ ﺗﺘﺤﺮك ﺑﻨﻔﺲ اﻟﻘﺪر ﻣﻤﺎ ﻳﺨﻠﻖ ﻣﺤﻼﻗًﺎ ﻃﻮﻳﻼً ﻣﻦ اﻟﻐﺒﺎر . أوﺿﺢ ﺳﺘﺎرك أن " ﻣﻼﻣﺢ ذﻳﻞ اﻟﻘﻄﺔ ﻏ ﻋﺎدﻳﺔ إﱃ ﺣﺪ ﻛﺒ وﻛﺎن ﻣـﻦ اﻟﺼﻌﺐ إﻋﺎدة إﻧ ﺘﺎج اﻻﻧﺤﻨـﺎء ﺑﻨﻤــﻮذج دﻳﻨــﺎﻣﻴﻜﻲ ﺣﻴــﺚ ﻳﺘﻄﻠﺐ ﻧﻤﻮذﺟﻨﺎ ﻏﺒﺎر اً ﻳﻤﻜـﻦ دﻓﻌﻪ ﺧﺎرج اﻟﻨﻈﺎم ﺑﺴ ﺮﻋﺔ ـ ﻛﺒ ة ﻣﻤﺎ ﻳﺸ ﻣﺮة أﺧﺮى إﱃ أﻧﻪ ﻣﺼﻨﻮع ﻣﻦ ﻣﺎدة ﻋﻀﻮﻳﺔ ـﻳـ ." ﺣﺮارﻳﺔ ﴩح اﻟﻨﻤـﻮذج ا ﻔﻀﻞ ﻟ ﻠﻔﺮﻳﻖ اﻟﺰاوﻳﺔ اﻟﺤﺎدة ﻟﻠــﺬﻳﻞ ﺑﻌﻴ ـﺪ اً ﻋ ـﻦ اﻟﻘ ـﺮص ﺑﺎﻋﺘﺒﺎره ﻣﺠﺮد ﴫي ـ ﺧﺪاع ﺑ إن . ﻂ ﺑﺴــﻴ ﻣﻨﻈﻮرﻧــﺎ ﻣــﻊ اﻟﺸﻜﻞ ا ﻨﺤﻨﻲ ﻟﻠـﺬﻳﻞ ﻳﺨﻠـﻖ اﻟﺰاوﻳـﺔ ا ﻠﺤﻮﻇـﺔ ﻟﻠـﺬﻳﻞ، ﰲ ﺣ أن ﻗﻮس ا ﺎدة ﻻ ﻳﻐـﺎد ر اﻟﻘﺮص إﻻ ﺑﻤﻴﻞ ﻗﺪره ﺧﻤﺲ درﺟﺎت ﻣﻊ اﻷﺧﺬ ﰲ اﻻﻋﺘﺒـﺎر ﺳﻄﻮع اﻟﺬﻳﻞ، ﻳﻘـﺪر اﻟﻔﺮﻳـﻖ ﻛﻤﻴﺔ اﻟﻐﺒﺎر داﺧﻞ ذﻳﻞ اﻟﻘﻄﺔ ﺗﻌﺎدل ﺣﺰام ﺎت ﻛﻮﻳﻜﺒ ـ رﺋﻴﺴ ﻲ ﻛﺒ ﻳﻨﺘــﴩ ﺴـﺎﻓﺔ ﻋﴩة ﻣﻠﻴﺎرات ﻣﻴﻞ . ﻳﻤﻜﻦ ﻟﺤـﺪث إﻧﺘـﺎج اﻟﻐﺒﺎر اﻷﺧ داﺧـﻞ أﻗـﺮاصﺣﻄـﺎم ﺑﻴﺘـﺎ ﺑﻴﻜﺘﻮرﻳﺲ أن ﻳﻔﴪ أﻳﻀًـﺎ اﻻﻣﺘـ ﺪاد ﻏـ ا ﺘﻤﺎﺛﻞ اﻟﺬي ﺷﻮﻫﺪ ﺣﺪﻳﺜ ﺎً ﻟﻠﻘﺮص اﻟﺪاﺧﲇ ا ﺎﺋﻞ ﻛﻤﺎ ﻫﻮ ﻣﻮﺿـﺢ ﰲ ﺑﻴﺎﻧـﺎت ﻛـﺎﻣ ا ﻣـ ي وﻻ ﻳُـﺮى إﻻ ﻋـﲆ اﻟﺠﺎﻧـﺐ ا ﻘﺎﺑـﻞ ﻟﻠــﺬﻳﻞ . ﻳﻤﻜــﻦ أن ﻳﻜ ـﻮن إﻧﺘ ـﺎج اﻟﻐﺒ ـﺎر اﻻﺻﻄﺪاﻣﻲ اﻷﺧ أﻳﻀً ﺎ ﻣﺴﺆوﻻً ﻋﻦ ﻣﻴﺰة ﺗﻢ رﺻـﺪﻫﺎ ﺳـﺎﺑﻘ ﺎً ﺑﻮاﺳـﻄﺔ ﻣﺼـﻔﻮﻓﺔ أﺗﺎﻛﺎﻣــﺎ ا ﻠﻴﻤﱰﻳــﺔ / ﺗﺤــﺖ ا ﻠﻴﻤﱰﻳــﺔ اﻟﻜﺒ ة ﰲ ﻋﺎم 2014 : ﻛﺘﻠﺔ ﻣﻦ أول أﻛﺴﻴﺪ اﻟﻜﺮﺑﻮن )CO( ﺗﻮﺟـﺪ ﺑﺎﻟﻘﺮب ﻣﻦ ذﻳﻞ اﻟﻘﻄـﺔ وﺑﻤـﺎ أن إﺷـﻌﺎع اﻟﻨﺠﻢ ﻳﺠﺐ أن ﻳﻔﻜﻚ ﺛﺎﻧﻲ أﻛﺴﻴﺪ اﻟﻜﺮﺑﻮن ﰲ ﻏﻀﻮن ﻣﺎﺋﺔ ﻋﺎم ﺗﻘﺮﻳﺒـﺎً ﻓـﺈن ﺗﺮﻛﻴـﺰ اﻟﻐﺎز اﻟﺬي ﻻ ﻳﺰال ﻣﻮﺟﻮد اً ﻳﻤﻜﻦ أن ﻳﻜﻮن دﻟﻴﻼً ﺑﺎﻗﻴﺎً ﻋﲆ ﻧﻔﺲ اﻟﺤﺪث . ﻗـﺎل ﺳـﺘﺎرك " : ﻳﺸـ ﺑﺤﺜﻨـﺎ إﱃ أن ﺑﻴﺘــﺎ ﺑﻴﻜﺘــﻮرﻳﺲ ﻗــﺪ ﺗﻜــﻮن أﻛﺜــﺮ ﻧﺸــﺎﻃ ﺎً وﻓﻮﺿﻮﻳﺔ ﻣﻤﺎ ﻛﻨﺎ ﻧﻌﺘﻘﺪ ﺳﺎﺑﻘًﺎ و ﻳﺴـﺘﻤﺮ ﺗﻠﺴــﻜﻮب ﺟــﻴﻤﺲ وﻳــ ﺐ اﻟﻔﻀــﺎﺋﻲ ﰲ ﻣﻔﺎﺟﺄﺗﻨﺎ ﺣﺘﻰ ﻋﻨﺪ اﻟﻨﻈﺮ إﱃ أﻛ ﺜﺮ اﻷﺟﺴﺎم اﻟﺘﻲ ﺗﻤﺖ دراﺳـﺘﻬﺎ ﺟﻴـﺪا ﻟـﺪﻳﻨﺎ و ﻧﻈـﺮة ﺟﺪﻳﺪة ﻋﲆ ﻫﺬه اﻷﻧﻈﻤﺔ اﻟﻜﻮﻛﺒﻴﺔ .