Free Astronomy Magazine March-April 2023 ARABIC VERSION

ject with the density of the icy moons of the Solar System, but sig- nificantly larger and more massive, clearly demonstrates the great di- versity of exoplanets,” added team member Jose-Manuel Almenara of Grenoble Alpes University in France. “This is expected to be the outcome of a variety of formation and evo- lution processes.“ Researchers caution that the plan- ets may not have oceans like those on Earth directly at the planet’s sur- face. “The temperature in Kepler- 138 d’s atmosphere is likely above the boiling point of water, and we expect a thick dense atmosphere made of steam on this planet. Only under that steam atmosphere could there potentially be liquid water at high pressure, or even water in another phase that occurs at high pressures, called a supercritical fluid,” Piaulet said. The NASA/ESA/CSA James Webb Space Telescope will also facilitate valuable follow-up research. “Now that we have securely identified the ‘water-world’ Kepler-138 d, the James Webb Space Telescope is the key to unveiling the atmospheric composition of such an exotic ob- ject,” shared team member Daria Kubyshkina of the Austrian Acad- emy of Sciences. “It will give us crit- ical information enabling us to compare the composition of the icy moons of the solar system with that of their larger and heavier extraso- lar counterparts.” Recently, another team at the Uni- versity of Montreal found a planet, called TOI-1452 b, that could poten- tially be covered with a liquid-wa- ter ocean, but Webb will be needed to also confirm this. In 2014, data from the NASA Kepler Space Tele- scope allowed astronomers to an- nounce the detection of three planets orbiting Kepler-138, a red dwarf star in the constellation Lyra. This was based on a measurable dip in starlight as each planet momen- tarily passed in front of the star. Benneke and his colleague Diana Dragomir, from the University of New Mexico, came up with the idea of re-observing the planetary sys- tem with the Hubble and Spitzer space telescopes between 2014 and 2016 to catch more transits of Ke- pler-138 d, the third planet in the system, in order to study its atmos- phere. While the earlier Kepler space telescope observations only showed transits of three small plan- ets around Kepler-138, Piaulet and her team were surprised to find that the Hubble and Spitzer obser- vations required the presence of a fourth planet in the system, Kepler- 138 e. This newly found planet is small and farther from its star than the three others, taking 38 days to complete an orbit. The planet is in the habitable zone of its star, a tem- perate region where it receives just the right amount of heat from its cool star to be neither too hot nor too cold to allow the presence of liquid water. The nature of this additional, newly found planet, however, remains an open question because it does not seem to transit its host star. Observ- ing the exoplanet’s transit would have allowed astronomers to deter- mine its size. “As our instruments and techniques become sensitive enough to find and study planets that are farther from their stars, we might start finding a lot more of these water worlds,” Benneke con- cluded.     ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ٣٢ ﺗﺴﺘﻜﺸـﻒﺣﻠﻘـﺔ Hubblecast ـ اﻟـ ـﺔ ﺠﺪ ﺪة ﻫـﺬﻩ ﻣـﺎ ﻤﻜﻨﻨـﺎ ﺗﻌﻠﻤـﮫ ﻣـﻦ ﺧـﻼل ﻋﺒـﻮراﻟ ﻮاﻛـﺐ ا ﺎرﺟ . ـﺎ ﻤـﺎ ﻳﺨ ــــﺎت اﻟﻌﺒــــﻮر ﻫــــﺬﻩ ﻤﺴــــﺎﻋﺪة ﻫﺎﺑــــﻞ وﻣــــﺎ ﻫــــﻲ اﻻ أ ﻀًــــﺎ ﻤــــﺎ ﺗﻌﻠﻤﻨــــﺎﻩ ﻣــــﻦ ﻋﻤﻠ ﻤﻜﻨﻨــــﺎ ﺗﻮﻗﻌﻬــــﺎ ﻛﺘﺸــــﺎﻓﺎت اﻟــــ ﺎﺳﺘﺨﺪام ﺗﻠﺴ ﻮبﺟ ﻤﺲو ﺐ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻟﻜﻨﺪ ﺔ ] . ﻧﺎﺳﺎ ، و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ ، ESO / L. ﺎﻟﺴﺎدا ، إم ﻮرﻤ ﺴﺮ ] وﻫﺬا ﻣﺜ ﻟﻠﺪﻫﺸﺔ ﻷن ﻣﻌﻈﻢ اﻟﻜﻮاﻛﺐ اﻟﺘﻲ ﻛﺎﻧﺖ أﻛﱪ ﺑﻘﻠﻴـﻞ ﻣـﻦ اﻷرض واﻟﺘـﻲ ﺗﻤـﺖ دراﺳﺘﻬﺎ ﺑﺎﻟﺘﻔﺼﻴﻞ ﺣﺘﻰ اﻵن ﺑﺪت ﺟﻤﻴﻌﻬـﺎ وﻛﺄﻧﻬﺎ ﻋﻮاﻟﻢ ﺻـﺨﺮﻳﺔ ﻣﺜـﻞ ﻋﺎ ﻨـﺎ . ﻳﻘـﻮل اﻟﺒﺎﺣﺜﻮن إن أﻗﺮب ﻣﻘﺎرﻧﺔ ﺳـﺘﻜﻮن ﺑﻌـﺾ اﻷﻗﻤــﺎر اﻟﺠﻠﻴﺪﻳــﺔ ﰲ اﻟﺠــﺰء اﻟﺨــﺎرﺟﻲ ﻟﻠﻤﺠﻤﻮﻋﺔ اﻟﺸﻤﺴﻴﺔ واﻟﺘـﻲ ﺗﺘﻜـﻮن أﻳﻀًـﺎ ﺑﺸﻜﻞ ﻛﺒ ﻣﻦ ا ﻴﺎه ا ﺤﻴﻄﺔ ﺑﻨﻮاة ﺻﺨﺮﻳﺔ . أوﺿﺤ ﺖ : "ﻪ ﺑﻴﺎوﻟﻴ ﺗﺨﻴـﻞ ﻧﺴـﺨًﺎ أﻛـ ﱪ ﻣـﻦ اﻟﻘﻤﺮ ﻳﻮروﺑﺎ أو إﻧﺴﻴﻼدوس اﻷﻗﻤﺎر اﻟﻐﻨﻴـﺔ ﺑﺎ ﻴﺎه اﻟﺘﻲ ﺗﺪور ﺣﻮل ﻛﻮﻛﺐ ا ﺸﱰي وزﺣﻞ وﻟﻜﻨﻬﺎ اﻗﱰﺑﺖ ﻛﺜ ًا ﻣﻦ ﻧﺠﻤﻬﺎ " ." ﺑﺪﻻً ﻣـﻦ ﺳﻄﺢ ﺟﻠﻴﺪي ﻛﺎﻧﺖ ﺗﺤﺘﻮ ي ﻋـﲆ ﻣﻈـﺎرﻳﻒ ﻛﺒ ة ﻣﻦ ﺑﺨﺎر ا ﺎء وأﺿﺎف ﻋﻀـﻮ اﻟﻔﺮﻳـﻖ ﺟﻮزﻳﻪ ﻣﺎﻧﻮﻳﻞ أ ﻴﻨﺎرا ﻣﻦ ﺟﺎﻣﻌﺔ ﻏﺮوﻧﻮﺑـﻞ أﻟﺐ ﰲ ﻓﺮﻧﺴﺎ " : إن اﻟﺘﻌﺮف اﻵﻣﻦ ﻋﲆ ﺟﺴـﻢ ﺑﻜﺜﺎﻓــﺔ اﻷﻗﻤــﺎر اﻟﺠﻠﻴﺪﻳــﺔ ﻟﻠﻤﺠﻤﻮﻋــﺔ اﻟﺸﻤﺴﻴﺔ ، وﻟﻜﻨﻪ أﻛﱪ وأﻛﱪ ﺑﻜﺜ ، ﻳﻮﺿـﺢ ﺑﻮﺿﻮح اﻟﺘﻨﻮع اﻟﻜﺒ ﻟﻠﻜﻮاﻛﺐ اﻟﺨﺎرﺟﻴـﺔ " " ﻣﻦ ا ﺘﻮﻗﻊ أن ﻳﻜﻮ ن ﻫﺬا ﻧﺘﻴﺠـﺔ ﺠﻤﻮﻋـﺔ ﻣﺘ ﻨﻮﻋﺔ ﻣﻦ ﻋﻤﻠﻴﺎت اﻟﺘﻜﻮﻳﻦ واﻟﺘﻄﻮر . ﺗﻘــﻮل ﺑﻴﺎوﻟﻴـ :ﻪ ﻳﺤـﺬر اﻟﺒـﺎﺣﺜﻮن ﻣـﻦ أن اﻟﻜﻮاﻛﺐ ﻗﺪ ﻻ ﺗﺤﺘﻮي ﻋﲆ ﻣﺤﻴﻄﺎت ﻣﺜﻞ ﺗﻠﻚ ا ﻮﺟﻮدة ﻋﲆ اﻷرض ﻣﺒـﺎﴍة ﻋـﲆ ﺳـﻄﺢ اﻟﻜﻮﻛـﺐ " . ﻣـﻦ ا ﺤﺘﻤــﻞ أن ﺗﻜـﻮن درﺟـﺔ اﻟﺤﺮارة ﰲ اﻟﻐﻼف اﻟﺠـﻮي ﻟ - ﻜﺒﻠـﺮ ١٣٨ دي أﻋﲆ ﻣﻦ ﻧﻘﻄﺔ ﻏﻠﻴﺎن ا ـ ﺎء ، وﻧﺘﻮﻗـﻊ ﺟـﻮًا ﻛﺜﻴﻔًﺎ ﻛﺜﻴﻔًﺎ ﻣﺼﻨﻮﻋًﺎ ﻣﻦ اﻟﺒﺨـﺎر ﻋـﲆ ﻫـﺬا اﻟﻜﻮﻛﺐ . ﻓﻘﻂ ﺗﺤـﺖ ﻫـﺬا اﻟﻐـﻼف اﻟﺠـﻮي اﻟﺒﺨﺎري ﻳﻤﻜﻦ أن ﻳﻜﻮن ﻫﻨـﺎك ﻣـﺎء ﺳـﺎﺋﻞ ﺗﺤﺖ ﺿﻐﻂ ﻣﺮﺗﻔﻊ ، أو ﺣﺘﻰ ﻣﺎء ﰲ ﻣﺮﺣﻠـﺔ أﺧﺮى ﺗﺤﺪث ﻋﻨﺪ ﺿﻐﻮط ﻋﺎﻟﻴﺔ ﺗﺴﻤﻰ ﺳﺎﺋﻞ ﻓﻮق اﻟﺤﺮج . ﻳﻘﻮل ﻋﻀﻮ اﻟﻔﺮﻳﻖ ا ﺸﱰك دارﻳﺎ ﻛﻮﺑﻴﺸﻜﻴﻨﺎ ﻣﻦ اﻷﻛﺎ دﻳﻤﻴﺔ اﻟﻨﻤﺴﺎوﻳﺔ ﻟﻠﻌﻠﻮم : ﺳﻴﺴـﻬﻞ ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ اﻟﻔﻀﺎﺋﻲ أﻳﻀًﺎ أﺑﺤﺎث ا ﺘﺎﺑﻌﺔ اﻟﻘﻴﻤﺔ " . اﻵن ﺑﻌﺪ أن ﺣﺪدﻧﺎ اﻟﻜﻮﻛﺐ ا ــﺎ " ﺋﻲ - ﻛﺒﻠ ـﺮ ١٣٨ دي ، ﻓ ـﺈن ﺗﻠﺴــﻜﻮب ﺟﻴﻤﺲ وﻳﺐ اﻟﻔﻀﺎﺋﻲ ﻫﻮ ا ﻔﺘـﺎح ﻟﻜﺸـﻒ اﻟﻨﻘﺎب ﻋﻦ ﺗﻜﻮﻳﻦ اﻟﻐﻼف اﻟﺠﻮي ﺜـﻞ ﻫـﺬا اﻟﺠﺴﻢ اﻟﻐﺮﻳﺐ "، اﻟﺠﺴﻢ اﻟﻐﺮﻳﺐ ﺳﺘﻮﻓﺮ ﻟﻨﺎ ﻣﻌﻠﻮﻣﺎت ﻣﻬﻤـﺔ ﺗﻤﻜﻨﻨﺎ ﻣﻦ ﻣﻘﺎرﻧﺔ ﺗﻜﻮﻳﻦ اﻷﻗﻤﺎر اﻟﺠﻠﻴﺪﻳـﺔ ﻟﻠﻨﻈﺎ م اﻟﺸﻤﴘ ﻣﻊ ﺗﻜﻮﻳﻦ ﻧﻈﺮاﺋ ﻬﺎ اﻷﻛـﱪ واﻷﺛﻘـﻞ ﺧـﺎرج ا ﺠﻤﻮﻋـﺔ اﻟﺸﻤﺴــﻴﺔ ﰲ . " اﻵوﻧﺔ اﻷﺧ ة وﺟـﺪ ﻓﺮﻳـﻖ آﺧـﺮ ﰲ ﺟﺎﻣﻌـﺔ ﻣﻮﻧﱰﻳﺎل ﻛﻮﻛﺒًﺎ ، ﻳُﺪﻋﻰ TOI-1452 b ، ﻣـﻦ ا ﺤﺘﻤﻞ أن ﻳﻜ ﻮن ﻣﻐﻄﻰ ﺑﻤﺤﻴﻂ ﻣـﻦ ا ـﺎء اﻟﺴﺎﺋﻞ ﻟﻜﻦ ﻴﺳـ ﻜﻮن ﻫﻨـﺎك ﺣﺎﺟـﺔ ﻟﻘﻴـﺎم ﺗﻠﺴﻜﻮب ﺟﻴﻤﺲ وﻳﺐ ﺑ ﺘﺄ ﻛﻴﺪ ذﻟﻚ أﻳﻀًﺎ . ﻟﻘﺪ ﺳﻤﺤﺖ ﺑﻴﺎﻧﺎت ﻣﻦ ﺗﻠﺴﻜﻮب ﺒﻠﺮﻛ اﻟﻔﻀﺎﺋﻲ ﻋــﺎم ٢٠١٤ ﻟﻌﻠﻤ ـﺎء اﻟﻔﻠ ـﻚ ﺑ ـﺎﻹﻋﻼن ﻋ ـﻦ اﻛﺘﺸﺎف ﺛﻼﺛﺔ ﻛﻮاﻛﺐ ﺗﺪور ﺣﻮل ﻛﺒﻠـﺮ ١٣٨ وﻫﻮ ﻧﺠﻢ ﻗﺰم أﺣﻤﺮ ﰲ ﻛﻮﻛﺒﺔ اﻟﻘﻴﺜﺎرة ﻟﻘـﺪ ﻛﺎن ﻫﺬا ﻣﺒﻨﻴًـ ﺎ ﻋـﲆ اﻧﺨﻔـﺎض ﻣﻠﻤـﻮس ﰲ ﻢ ﺿﻮء اﻟﻨﺠ ﻛﻠﻤﺎ ﻣﺮ ﻛﻮﻛﺐ ﻟﻠﺤﻈـﺎت أﻣـﺎم اﻟﻨﺠﻢ . ﺗﻮﺻﻞ ﺑﻴﻨﻜﻲ وزﻣ ﻴﻠﺘﻪ دﻳﺎﻧﺎ دراﻏﻮﻣ ﻣﻦ ﺟﺎﻣﻌﺔ ﻧﻴﻮ ﻣﻜﺴـﻴﻜﻮ إﱃ ﻓﻜـﺮة إﻋـﺎدة ﻣﺮاﻗﺒﺔ ﻧﻈﺎم اﻟﻜﻮاﻛﺐ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮﺑﺎت ﻫﺎﺑﻞ وﺳﺒﻴﺘﺰر اﻟﻔﻀﺎﺋﻴ ﺑ ﻋـﺎﻣﻲ ٢٠١٤ و ٢٠١٦ ﻻﻟﺘﻘﺎط ا ﺰﻳﺪ ﻣـﻦ ﻋﻤﻠﻴـﺎت ﻋﺒـﻮر ﻛﻮﻛ - ﺐ ﻛﺒﻠـﺮ ١٣٨ دي ، اﻟﻜﻮﻛـﺐ اﻟﺜﺎﻟـﺚ ﰲ ذﻟﻚ اﻟﻨﻈﺎم ﻟﺪراﺳﺔ اﻟﻐـﻼف اﻟﺠـﻮي ﺑﻴﻨﻤـﺎ ارﺻﺎد ﺗﻠﺴﻜﻮب ﻛ ﺒﻠـﺮ اﻟﺴـﺎﺑﻘﺔ ﻟـﻢ ﺗﻈﻬـﺮ ــــ ﺴﺎﺑﻖ ﻛﺒﻠﺮ ﺳﻮى ﻋﺒﻮر ﺛﻼﺛﺔ ﻛﻮاﻛﺐ ﺻﻐ ة ﺣﻮل اﻟﻨﺠﻢ - ﻛﺒﻠﺮ ١٣٨ ﻟﺬﻟﻚ ﻓﻮﺟﺌﺖ ﺑﻴﺎوﻟ ﻴـﻪ وﻓﺮﻳﻘﻬـﺎ ﻋﻨﺪﻣﺎ اﻛﺘﺸﻔﻮا أن أرﺻـﺎد ﻫﺎﺑـﻞ وﺳـﺒﻴﺘﺰر ﺗﺘﻄﻠﺐ وﺟﻮد ﻛﻮﻛﺐ راﺑـﻊ ﰲ اﻟﻨﻈـﺎم وﻫـﻮ - ﻛﺒﻠﺮ ١٣٨ . إي ﻫﺬا اﻟﻜﻮ ﻛﺐ ا ﻜﺘﺸﻒﺣﺪﻳﺜًﺎ ﺻﻐ وأﺑﻌﺪ ﻋﻦ ﻧﺠﻤﻪ ﻋﻦ اﻟﺜﻼﺛﺔ اﻷﺧﺮى وﻳﺴﺘﻐﺮق ٣٨ ﻳﻮﻣًﺎ ﻹﻛﻤﺎل ﻣﺪاره . ﻳﻮﺟﺪ اﻟﻜﻮﻛﺐ ﰲ ا ﻨﻄﻘﺔ اﻟﺼـﺎﻟﺤﺔ ﻟﻠﺴـﻜﻦ ﻧﺠﻤﻪ ﺣﻮل وﻫـﻲ ﻣﻨﻄﻘـﺔ درﺟـﺔ اﻟﺤـﺮارة ا ﻌﺘﺪﻟﺔ ﺣﻴﺚ ﻳﺘﻠﻘﻰ ﻓﻘﻂ اﻟﻜﻤﻴـﺔ ا ﻨﺎﺳـﺒﺔ ﻣﻦ اﻟﺤﺮارة ﻣﻦ ﻧﺠﻤﻪ اﻟﺒﺎرد ) ﻧﺴـﺒﻴﺎً ( ﻣﻤـﺎ ﻳﺴﻤﺢ ﺑﻮﺟﻮد ا ﺎء اﻟﺴﺎﺋ ﻞ وﻣـﻊ ذﻟـﻚ ﺗﻈـﻞ ﻃﺒﻴﻌﺔ ﻫﺬا اﻟﻜﻮﻛﺐ اﻹﺿﺎﰲ ا ﻜﺘﺸﻒ ﺣﺪﻳﺜًﺎ ﺳﺆاﻻً ﻣﻔﺘﻮﺣًﺎ ﻷﻧﻪ ﻻ ﻳﺒﺪو أﻧﻪ ﻳﻌـﱪ ﻧﺠﻤـﻪ ا ﻀﻴﻒ . ﻟﻘﺪ ﻛﺎﻧـﺖ ﻣﺮاﻗﺒـﺔ ﻋﺒـﻮر ﻛﻮﻛـﺐ ﺧﺎرج ا ﺠﻤﻮﻋﺔ اﻟﺸﻤﺴﻴﺔ ﺳﺘﺴﻤﺢ ﻟﻌﻠﻤـﺎء اﻟﻔﻠﻚ ﺑﺘﺤﺪﻳﺪ ﺣﺠﻤﻪ . واﺧﺘــﺘﻢ ﺑﻴﻨﻴﻜــﻲ " : ﻧﻈــﺮًا ﻷن اﺟﻬﺰﺗﻨــﺎ وﺗﻘﻨﻴﺎﺗﻨﺎ أﺻﺒﺤﺖ ﺣﺴﺎﺳﺔ ﺑﺪرﺟـﺔ ﻛﺎﻓﻴـﺔ ﻟﻠﻌ ﺜﻮر ﻋﲆ اﻟﻜﻮاﻛﺐ اﻟﺒﻌﻴـﺪة ﻋـﻦ ﻧﺠﻮﻣﻬـﺎ ودراﺳﺘﻬﺎ ، ﻓﻘﺪ ﻧﺒﺪأ ﰲ اﻟﻌﺜﻮر ﻋﲆ ا ﺰﻳﺪ ﻣﻦ اﻟﻜﻮاﻛﺐ ا ﻴﺎه ﻫﺬه ." ﻣﺎرس أﺑﺮﻳﻞ 2023