Free Astronomy Magazine March-April 2024 ARABIC VERSION

C ontrary to what you might think, galaxy colli- sions do not destroy stars. In fact, the rough- and-tumble dynamics trigger new genera- tions of stars, and presumably accompanying plan- ets. Now NASA’s Hubble Space Telescope has homed in on 12 interacting galaxies that have long, tad- pole-like tidal tails of gas, dust, and a plethora of stars. Hubble’s exquisite sharpness and sensitivity to ultraviolet light have uncovered 425 clusters of new- born stars along these tails, looking like strings of holiday lights. Each cluster contains as many as 1 million blue, newborn stars. Clusters in tidal tails have been known about for decades. When galaxies interact, gravitational tidal forces pull out long streamers of gas and dust. Two popular examples are the Antennae and Mice galax- ies with their long, narrow, finger-like projections. A team of astronomers used a combination of new observations and archival data to get ages and masses of tidal tail star clusters. They found that these clusters are very young — only 10 million years old. And they seem to be forming at the same rate along tails stretching for thousands of light-years. “It’s a surprise to see lots of the young objects in the tails. It tells us a lot about cluster formation effi- ciency,” said lead author Michael Rodruck of Ran- dolph-Macon College in Ashland, Virginia. “With tidal tails, you will build up new generations of stars that otherwise might not have existed.” The tails look like they are taking a galaxy’s spiral arm and stretching it out into space. The exterior part of the arm gets pulled like taffy from the grav- itational tug-of-war between a pair of interacting galaxies. Before the mergers, the galaxies were rich in dusty clouds of molecular hydrogen that simply may have remained inert. But the clouds got jostled and bumped into each other during the encounters. This compressed the hydrogen to the point where it precipitated a firestorm of star birth. The fate of these strung-out star clusters is uncer- tain. They may stay gravitationally intact and evolve into globular star clusters — like those that orbit outside the plane of our Milky Way galaxy. Or they may disperse to form a halo of stars around their host galaxy, or get cast off to become wandering in- tergalactic stars. This string-of-pearls star formation may have been more common in the early universe when galaxies collided with each other more frequently. These nearby galaxies observed by Hubble are a proxy for what happened long ago, and therefore are labo- ratories for looking into the distant past.     MARCH-APRIL 2024 ﻌﻜﺲ ﻣﺎ ﻗﺪ ﺗﻌﺘﻘﺪ ﻓﺈن اﺻﻄﺪاﻣﺎت ا ﺠﺮات ﻻ ﺗﺪﻣﺮ اﻟﻨﺠﻮم . ﰲ اﻟﻮاﻗﻊ ﺗﺆدي اﻟﺪﻳﻨﺎﻣﻴﻜﻴﺎت ا ﺘﻘﻠﺒﺔ إﱃ إﻃﻼق أﺟﻴﺎل ﺟﺪﻳـﺪة ﻣﻦ اﻟﻨﺠﻮم وﻣﻦ ا ﺤﺘﻤﻞ أ ن ﺗﻜﻮن اﻟﻜﻮاﻛﺐ ﻣﺼﺎﺣﺒﺔ ﻟﻬﺎ اﻵن . ﻳ ﺮﻛﺰ ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎﺳـﺎ ﻋـﲆ 12 ﻣﺠـﺮة ﻣﺘﻔﺎﻋﻠﺔ ﻟﻬﺎ ذﻳﻮل ﻣﺪﻳﺔ ﻃﻮﻳﻠﺔ ﺗ ـ ﺸﺒﻪ اﻟ ﴩﻏﻮف ﻣﻜﻮﻧﺔ ﻣـﻦ اﻟﻐﺎز واﻟﻐﺒﺎر وﻋﺪد ﻛﺒ ﻣﻦ اﻟﻨﺠﻮم وﻗﺪ ﻛﺸﻔﺖ دﻗﺔ ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﺮاﺋﻌﺔ وﺣﺴﺎﺳﻴﺘﻪ ﻟﻠﻀﻮء ﻓـﻮق اﻟﺒﻨﻔﺴـﺠﻲ ﻋـﻦ 425 اً ﻋﻨﻘﻮد ﻣﻦ اﻟﻨﺠﻮم ﺣﺪﻳﺜﺔ اﻟﻮﻻدة ﻋﲆ ﻃﻮل ﻫﺬه اﻟﺬﻳﻮل، ﺗﺒـﺪو وﻛﺄﻧﻬﺎ ﺧﻴﻮط ﻣﻦ أﺿﻮاء اﺣﺘﻔﺎﻻت اﻟﻌﻄﻠﺔ . ﺗﺤﺘﻮي ﻛﻞ ﻣﺠﻤﻮﻋﺔ ﻋﲆ ﻣﺎ ﻳﺼﻞ إﱃ ﻣﻠﻴﻮن ﻧﺠﻢ أزرق ﺣـﺪﻳﺚ اﻟﻮﻻدة . ﻟﻘﺪ ﻋُﺮﻓﺖ ا ﺠﻤﻮﻋﺎت ا ﻮﺟﻮدة ﰲ ذﻳﻮل ا ـﺪ واﻟﺠـﺰر ﻣﻨﺬ . ﻋﻘﻮد ﻋﻨﺪﻣﺎ ﺗﺘﻔﺎﻋﻞ ا ﺠﺮات، ﺗﺴﺤﺐ ﻗﻮى ا ـﺪ واﻟﺠـﺰر اﻟﺠﺎذﺑﻴﺔ ﺗﻴﺎرات ﻃﻮﻳﻠﺔ ﻣﻦ اﻟﻐﺎز واﻟﻐﺒﺎر . ﻫﻨﺎك ﻣﺜﺎﻻن ﺷﺎﺋﻌﺎن ﻫﻤﺎ ﻣﺠﺮﺗـﻲ اﻟﻬﻮاﺋﻴـﺎت واﻟﻔـﱤان ﻣـﻊ ﻧﺘﻮءاﺗﻬﺎ اﻟﻄﻮﻳﻠﺔ واﻟﻀﻴﻘﺔ اﻟﺘﻲ ﺗﺸﺒﻪ اﻷﺻﺎﺑﻊ . اﺳﺘﺨﺪم ﻓﺮﻳﻖ ﻣﻦ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﻣﺠﻤﻮﻋـﺔ ﻣـﻦ ا ﻼﺣﻈـﺎت اﻟﺠﺪﻳﺪة واﻟﺒﻴﺎﻧـﺎت اﻷرﺷـﻴﻔﻴﺔ ﻟﻠﺤﺼـﻮل ﻋـﲆ أﻋﻤـﺎر وﻛﺘـﻞ ﻣﺠﻤﻮﻋﺎت اﻟﻨﺠﻮم اﻟﺘﻴﻠﻴﺔ ا ﺪﻳـﺔ و وﺟـﺪوا أن ﻫـﺬه اﻟﻌﻨﺎﻗﻴـﺪ اً ﺻﻐ ة ﺟﺪ ﻋﻤﺮﻫﺎ 10 ﻣﻼﻳ ﺳﻨﺔ ﻓﻘﻂ وﻳﺒﺪو أﻧﻬـﺎ ﺗﺘﺸـﻜﻞ ﺑﻨﻔﺲ ا ﻌﺪل ﻋﲆ ﻃﻮل ذﻳـﻮل ﺗﻤﺘـﺪ ﻵﻻف اﻟﺴـﻨ اﻟﻀـﻮﺋﻴﺔ . " إﻧﻬﺎ ﻣﻔﺎﺟﺄة أن ﻧﺮى اﻟﻜﺜ ﻣﻦ اﻷﺷﻴﺎء اﻟﺼـﻐ ة ﰲ اﻟـﺬﻳﻮل . ﻗﺎل ا ﺆﻟ ﻒ اﻟﺮﺋﻴﴘ ﻣﺎﻳﻜﻞ رودراك ﻣﻦ ﻛﻠﻴﺔ راﻧﺪوﻟﻒ ﻣﺎﻛﻮن ﰲ أﺷﻼﻧﺪ ﺑﻮﻻﻳﺔ ﻓ ﺟﻴﻨﻴﺎ :» إﻧﻬﺎ ﺗﺨﱪﻧﺎ اﻟﻜﺜ ﻋﻦ ﻛﻔﺎءة ﺗﻜـﻮﻳﻦ ا ﺠﻤﻮﻋ . "« ﺎت ﺑﺎﺳﺘﺨﺪام ذﻳـﻮل ا ـﺪ واﻟﺠـﺰر ﺳـﺘﺒﻨﻲ أﺟﻴـﺎﻻً ﺟﺪﻳﺪة ﻣﻦ اﻟ ﻨﺠﻮم اﻟﺘﻲ ﻟﻢ ﺗﻜﻦ ﻟﺘﻮﺟﺪ ﻟﻮﻻ ذﻟﻚ " . ﺗﺒﺪو اﻟﺬﻳﻮل وﻛﺄﻧﻬﺎ ﺗﺄﺧﺬ ذراع ا ﺠـﺮة اﻟﺤﻠﺰوﻧـﻲ وﺗﻤـﺪﻫﺎ إﱃ اﻟﻔﻀﺎء و ﻳﺘﻢ ﺳﺤﺐ اﻟﺠﺰء اﻟﺨﺎرﺟﻲ ﻣﻦ اﻟـﺬراع ﻣﺜـﻞ ﻗﻄﻌـﺔ اﻟﺤﻠﻮى ﻣﻦ ﻟﻌﺒﺔ ﺷﺪ اﻟﺤﺒﻞ اﻟﺠﺎذﺑﻴﺔ ﺑـ زوج ﻣـﻦ ا ﺠـﺮات ا ﺘﻔﺎﻋﻠﺔ . ﻗﺒﻞ ﻋﻤﻠﻴﺎت اﻻﻧﺪﻣﺎج ﻛﺎﻧﺖ ا ﺠﺮات ﻏﻨﻴﺔ ﺑﺎﻟﺴﺤﺐ اﻟﻐﺒﺎرﻳـﺔ ﻟﻠﻬﻴﺪروﺟ اﻟﺠﺰﻳﺌﻲ، واﻟﺘﻲ رﺑﻤﺎ ﻇﻠﺖ ﺧﺎﻣﻠﺔ . ﻟﻜـﻦ اﻟﺴـﺤﺐ ﺗﺰاﺣﻤﺖ واﺻﻄﺪﻣﺖ ﺑﺒﻌﻀﻬﺎ اﻟﺒﻌ . ﺾ ﺧﻼل اﻟﻠﻘﺎءات أدى ﻫﺬا إﱃ ﺿﻐﻂ اﻟﻬﻴﺪروﺟ إﱃ اﻟﻨﻘﻄﺔ اﻟﺘﻲ أدت إﱃ ﺣﺪوث ﻋﺎﺻـﻔﺔ ﻧﺎرﻳﺔ ﻣﻦ وﻻدة اﻟﻨﺠﻮم . إن ﻣﺼ ﻫﺬه اﻟﻌﻨﺎﻗﻴﺪ اﻟﻨﺠﻤﻴﺔ ا ﻌﻠﻘﺔ ﻏ ﻣﺆﻛﺪ . وﻗﺪ ﺗﻈـﻞ ﺳﻠﻴﻤﺔ ﻣﻦ ﺣﻴـﺚ اﻟﺠﺎذﺑﻴـﺔ وﺗﺘﻄـﻮر إﱃ ﻣﺠﻤﻮﻋـﺎت ﻧﺠﻤﻴـﺔ ﻛﺮوﻳﺔ، ﻣﺜﻞ ﺗﻠﻚ اﻟﺘﻲ ﺗﺪور ﺧﺎرج ﻣﺴﺘﻮى ﻣﺠﺮﺗﻨﺎ درب اﻟﺘﺒ . ﺎﻧﺔ أو ﻗﺪ ﺗﺘﻔﺮق ﻟﺘﺸﻜﻞ ﻫﺎﻟﺔ ﻣﻦ اﻟﻨﺠﻮم ﺣﻮل ﻣﺠﺮﺗﻬﺎ ا ﻀـﻴﻔﺔ، أو ﻳﺘﻢ اﻟﺘﺨﻠﺺ ﻣﻨﻬﺎ ﻟﺘﺼﺒﺢ ﻧﺠﻮﻣًﺎ ﻣﺘﺠﻮﻟﺔ ﺑ ا ﺠﺮات . رﺑﻤﺎ ﻛﺎن ﺗﺸﻜﻞ اﻟﻨﺠﻮم ﻋﲆ ﺷﻜﻞ ﺳﻠﺴـﻠﺔ ﻣـﻦ اﻟﻠﺆﻟـﺆ أﻛﺜـﺮ ﺷﻴﻮﻋًﺎ ﰲ اﻟﻜﻮن ا ﺒﻜﺮ ﻋﻨـﺪﻣﺎ اﺻـﻄﺪﻣﺖ ا ﺠـﺮات ﺑﺒﻌﻀـﻬﺎ اﻟﺒﻌﺾ ﺑﺸﻜﻞ ﻣﺘﻜﺮر . ﻫﺬه ا ﺠﺮات اﻟﻘﺮﻳﺒﺔ اﻟﺘﻲ ر ﺻﺪﻫﺎ ﻫﺎﺑﻞ ﻫﻲ وﻛﻴﻞ ﺎ ﺣﺪث ﻣﻨﺬ ﻓﱰة ﻃﻮﻳﻠﺔ، وﺑﺎﻟﺘـﺎﱄ ﻓﻬـﻲ ﻣﺨﺘـﱪات ﻟﻠﻨﻈﺮ ﰲ ا ﺎﴈ اﻟﺒﻌﻴﺪ . ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 33 - ﻣﺎﺭﺱ ﺃﺑﺮﻳﻞ 2 0 2 4 ﺗﻢ ﺗﺸﻮ ﮫ اﻟﻤﺠـﺮة AM 1054-325 إﻟـﻰﺷـ ﻞ ﻣـﻦﺷـ ﻞ ﺣﻠﺰوﻧـﻲ ﻋـﺎد ﺣـﺮف S ﺸـ ﮫ اﻟﻔﻄـ ة ﺴــ ﺐﺳـﺤﺐ اﻟـ ـ ﺠﺎذﺑ ﺔ ﻟﻤﺠــﺮة ﻣﺠـﺎورة ﻤـﺎ ﻈﻬــﺮ ﻓــﻲﻫــﺬﻩ اﻟﺼــﻮرة ا اﻟﺘﻘﻄﻬـﺎ ﺗﻠﺴــ ﻮبﻫﺎﺑـﻞ اﻟﻔﻀــﺎﺋﻲوﻧﺘﻴﺠــﺔ ﻟــﺬﻟﻚ ﻟــ ﺗﺘﺸـــ ﻞ ـــﺪ ﻋﻨﺎﻗ ﻣـــﻦ اﻟﻨﺠـــﻮم ﺣﺪ ﺜـــﺔ اﻟـــﻮﻻدة ﻋﻠـــﻰﻃـــﻮل ذﻳـــ ﻣﻤﺘـــﺪ ﻞ ﻣـــﺪ ﻵﻻف اﻟﻀـﻮﺋ ﺔ اﻟﺴــﻨ ﻣﻤــﺎ ﺸــ ﮫ ﻋﻘــﺪًا ﻣــﻦ اﻟﻠﺆﻟــﺆ وﻫــﻲ ﺗﺘﺸـ ﻞ ﻋﻨــﺪﻣﺎ ﺗﻨﻬــﺎرﻋﻘــﺪ ﻣــﻦ اﻟﻐـــﺎز ﻔﻌــﻞ اﻟــ ـ ــﻢ ﺣـــﺪ ﺚ ــﻮﻳﻦ ﺣـــﻮاﻟﻲﻣﻠﻴــﻮن ﻧ ﺠﺎذﺑ ﺔ ﻟﺘ اﻟﻮﻻدة ﻓﻲ ﻞ ﻋﻨﻘﻮد .