MSGID: 1:317/3 649d08df   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    ALMA digs deeper into the mystery of planet formation    
      
     Date:   
         June 28, 2023   
     Source:   
         National Institutes of Natural Sciences   
     Summary:   
         An international research team has observed disks around   
         19 protostars with a very high resolution to search for the   
         earliest signs of planet formation. This survey was motivated by   
         the recent findings that planet formation may be well-underway in   
         the more-evolved proto-planetary disks, but until now there had   
         been no systematic study to search for signs of planet formation   
         in younger protostellar systems.   
      
      
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   FULL STORY   
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   An international research team used the Atacama Large   
   Millimeter/submillimeter Array (ALMA) to observe disks around 19   
   protostars with a very high resolution to search for the earliest signs   
   of planet formation. This survey was motivated by the recent findings that   
   planet formation may be well-underway in the more- evolved proto-planetary   
   disks, but until now there had been no systematic study to search for   
   signs of planet formation in younger protostellar systems.   
      
   Planets form in a disk around a newborn star. These 'proto-planetary'   
   disks only last a few million years, meaning that a forming planetary   
   system only has this amount of time to finish its formation. However, it   
   is still not clear just how rapidly planet formation begins within these   
   disks. Recent ALMA observations have revealed that many proto-planetary   
   disks have substructures such as gaps and rings, indicating that planets   
   are already forming from the disk. "These previous results motivated us   
   to examine even younger disks around protostars to answer the question,   
   at what stage of star formation do planet forms," says Nagayoshi Ohashi at   
   Academia Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan),   
   who led the team.   
      
   The team observed disks around 19 protostars located within about   
   650 light- years from the Earth. This is the first systematic study   
   to investigate the detailed structure of disks around a large sample   
   of protostars with high angular resolution. The observations clearly   
   show that the disks around protostars are different from more-evolved   
   proto-planetary disks. Among the 19 protostars, rings, and gaps,   
   which are signs of planet formation, were observed only in a few   
   disks. Moreover, the ring structures are less distinct than those seen   
   in the proto-planetary disks.   
      
   "We did not expect to see such clear differences between disks around   
   protostars and more-evolved disks," says Ohashi. John Tobin, a Co-PI of   
   the program at the National Radio Astronomical Observatory (USA) adds   
   "Our results suggest that disks around protostars are not fully ready   
   for planet formation.   
      
   We believe that the actual formation of the planetary system progresses   
   rapidly in the 100,000 years to 1,000,000 years after star formation   
   begins."   
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Extrasolar_Planets # Solar_System # Stars # Galaxies #   
                   Kuiper_Belt # Eris_(Xena) # Astronomy # Jupiter   
       * RELATED_TERMS   
             o Eris_(dwarf_planet) o Venus o Phoenix_(spacecraft) o   
             Extrasolar_planet o Uranus o Definition_of_planet o Neptune   
             o Mercury_(planet)   
      
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   Story Source: Materials provided by   
   National_Institutes_of_Natural_Sciences. Note: Content may be edited   
   for style and length.   
      
      
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   Journal Reference:   
      1. Nagayoshi Ohashi, John J. Tobin, Jes K. Jo/rgensen, Shigehisa   
      Takakuwa,   
         Patrick Sheehan, Yuri Aikawa, Zhi-Yun Li, Leslie W. Looney,   
         Jonathan P.   
      
         Williams, Yusuke Aso, Rajeeb Sharma, Jinshi Sai (Insa Choi),   
         Yoshihide Yamato, Jeong-Eun Lee, Kengo Tomida, Hsi-Wei Yen, Frankie   
         J. Encalada, Christian Flores, Sacha Gavino, Miyu Kido, Ilseung   
         Han, Zhe-Yu Daniel Lin, Suchitra Narayanan, Nguyen Thi Phuong,   
         Alejandro Santamari'a- Miranda, Travis J. Thieme, Merel L. R. van   
         't Hoff, Itziar de Gregorio- Monsalvo, Patrick M. Koch, Woojin   
         Kwon, Shih-Ping Lai, Chang Won Lee, Adele Plunkett, Kazuya Saigo,   
         Shingo Hirano, Ka Ho Lam, Shoji Mori. Early Planet Formation in   
         Embedded Disks (eDisk). I. Overview of the Program and First   
         Results. The Astrophysical Journal, 2023; 951 (1): 8 DOI:   
         10.3847/1538-4357/acd384   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230628130448.htm   
      
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