MSGID: 1:317/3 6423beee   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Redness of Neptunian asteroids sheds light on early Solar System    
      
     Date:   
         March 28, 2023   
     Source:   
         Royal Astronomical Society   
     Summary:   
         Asteroids sharing their orbits with the planet Neptune have been   
         observed to exist in a broad spectrum of red color, implying the   
         existence of two populations of asteroids in the region, according   
         to a new study by an international team of researchers.   
      
      
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   FULL STORY   
   ==========================================================================   
   Asteroids sharing their orbits with the planet Neptune have been observed   
   to exist in a broad spectrum of red colour, implying the existence of   
   two populations of asteroids in the region, according to a new study by   
   an international team of researchers. The research is published in the   
   journal Monthly Notices of the Royal Astronomical Society: Letters.   
      
      
   ==========================================================================   
   The team of scientists from the USA, California, France, the Netherlands,   
   Chile and Hawaii observed 18 asteroids sharing the orbit of Neptune,   
   known as Neptunian Trojans. They are between 50 and 100 km in size and   
   are located at a distance of around 4.5 billion kilometres from the   
   Sun. Asteroids orbiting this far away are faint and so are challenging   
   for astronomers to study. Before the new work, only about a dozen   
   Neptunian Trojans had been studied, requiring the use of some of the   
   largest telescopes on Earth.   
      
   The new data were gathered over the course of two years using the WASP   
   wide field camera on the Palomar Observatory telescope in California,   
   the GMOS cameras on the Gemini North and South telescopes in Hawaii and   
   Chile, and the LRIS camera on the Keck Telescope in Hawaii.   
      
   Of the 18 observed Neptunian Trojans, several were much redder than   
   most asteroids, and compared with other asteroids in this group looked   
   at in previous studies. Redder asteroids are expected to have formed   
   much further from the Sun; one population of these is known as the Cold   
   Classical trans- Neptunian objects found beyond the orbit of Pluto, at   
   around 6 billion kilometres from the Sun. The newly observed Neptunian   
   Trojans are also unlike asteroids located in the orbit of Jupiter,   
   which are typically more neutral in colour.   
      
   The redness of the asteroids implies that they contain a higher proportion   
   of more volatile ices such as ammonia and methanol. These are extremely   
   sensitive to heat, and can rapidly transform into gas if the temperature   
   rises, so are more stable at large distances from the Sun.   
      
   The location of the asteroids at the same orbital distance as Neptune   
   also implies that they are stable on timescales comparable to the age   
   of the Solar System. They effectively act as a time-capsule, recording   
   the initial conditions of the Solar System.   
      
   The presence of redder asteroids among the Neptunian Trojans suggests   
   the existence of a transition zone between more neutral coloured and   
   redder objects. The redder Neptunian asteroids may have formed beyond this   
   transition boundary before being captured into the orbit of Neptune. The   
   Neptunian Trojans would have been captured into the same orbit as the   
   planet Neptune as the ice giant planet migrated from the inner solar   
   system to where it is now, some 4.5 billion kilometres from the Sun.   
      
   Lead author Dr Bryce Bolin of the NASA Goddard Space Flight Centre said,   
   "In our new work we have more than doubled the sample of Neptunian   
   Trojans studied with large telescopes. It's exciting to find the first   
   evidence of redder asteroids in this group."  "Because we have a larger   
   sample of Neptunian Trojans with measured colours, we can now start to   
   see major differences between asteroid groups. Our observations also   
   show that the Neptunian Trojans are also different in colour compared   
   to asteroid groups even further from the Sun. A possible explanation   
   may be that the processing of the surfaces of asteroids by the Sun's   
   heat may have different effects for asteroids at varying solar distances."   
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Solar_System # Sun # Space_Telescopes # Solar_Flare #   
                   Astronomy # Neptune # Space_Exploration # Pluto   
       * RELATED_TERMS   
             o Asteroid_belt o Near-Earth_asteroid o Asteroid o Neptune   
             o Satellite o Neptune's_natural_satellites o Redshift o   
             Solar_system   
      
   ==========================================================================   
   Story Source: Materials provided by Royal_Astronomical_Society. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. B T Bolin, C Fremling, A Morbidelli, K S Noll, J van Roestel, E K   
         Deibert, M Delbo, G Gimeno, J-E Heo, C M Lisse, T Seccull,   
         H Suh. Keck, gemini, and palomar 200-inch visible photometry   
         of red and very-red neptunian trojans. Monthly Notices of the   
         Royal Astronomical Society: Letters, 2023; 521 (1): L29 DOI:   
         10.1093/mnrasl/slad018   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230328145329.htm   
      
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